Sunday, November 29, 2009

Attraction & Olfaction

The fact human females would want sex at all outside of their monthly 6-day window of receptivity is an evolutionary problem. What practical purpose does it serve? Don't females have better things to do?

Well, of course we do - but even so, those females who prescribe to a "dual sexuality" (conceptive and not conceptive) mating strategy are actually more likely to reap both the genetic and material benefits in their mate(s). There have been studies that suggest when a female is not receptive she prefers males who exhibit strong paternal and supportive attributes. These are the "nice" guys who are often pitied because they don't "get the girl." This isn't entirely true - except perhaps from a male's perspective. It really depends upon how "getting the girl" is interpreted. All but six days of the month studies have shown females to show preference towards the devout paternal male, not the raucous bad boy who is well endowed (genetically).

I suppose I should pause here to explain an important concept in evolutionary biology that's relevant to this entry. I'm inferring that he who is considered of high genetic quality is the aggressive, eyebrow-pierced, pink polo-adorned male who is incapable of articulating anything that has two or more syllables. This is true to at least one extent explained by the sexy son hypothesis. The idea is that if a female mates with a male who is considered "attractive," she will have attractive male offspring who will be perceived as having the same appeal to the next generation of women. A vibrant example of this is the male peafowl (below).

image source

One can easily see why the dual sexuality strategy would be adaptive to our female ancestors. A female prefers the male with whom she can share parental duties and, when she's ovulating, the male who can maximize her reproductive success in the long run. In human and nonhuman monogamous animals, females engage in extra-pair copulations during ovulation if the benefits outweigh the costs (ie. if the extra-pair male is much more genetically compatible and of course, if they don't get caught).

Follow your nose...
There is mounting evidence that suggests female mate choices are made through cues that reflect genetic quality ("sexy son" indicators) and material benefits ("good dad" indicators). Sexy son indicators include vocal and facial masculinity, muscles, symmetry, and body scent intensity. Good dad indicators are passiveness and feminine facial features (eg. round face and eyes).

So... what does the pill have to do with how sexy a woman perceives a man's stench?

The reason the pill has such a strong effect on female mate preference is because it keeps a high level of progestin (a substitute for progesterone) and estrogen in the female's system. Progesterone is a mellowing hormone and the sister to estrogen, the controlling, all-powerful hormone that is responsible for feelings of aggression and seduction. The pill tricks the body into thinking it is in a pregnant state, during which estrogen and progesterone are peaking. When a female is pregnant she does not continue the uterine cycle because a fertile egg is already gestating.

So what do the two key components to hormonally-based birth control pills actually do?Progestin and estrogen prevent gonatropin-releasing hormone (GnRH) from being secreted by the hypothalamus. GnRH is the signal to the pituitary gland to produce follicle-stimulating hormone (FSH) and leutinizing hormone (LH). Once GnRH is blocked, the body does not secrete FSH, which prompts the body to grow a follicle, and LH, which triggers the release of the egg. The pill essentially freezes the natural cycle so it remains at a single stage for the entire month.

The data suggests that females who are on the pill (or pregnant) do not have the same sexual palette as the non-pill user. In a study that manipulated the facial features in 20 pictures of male faces to masculinize or feminize their attributes found normally cycling women prefer less masculine faces in a long-term context compared to more masculine faces in a short-term context. Pill-users had an inverse preference and a weaker preference.

Love at first smell and contraceptives

The Major Histocompatibility Complex (MHC) is a gene family that serves as an important component to a person's immune system. It creates molecules capable of identifying pathogens, or foreign invaders, so that the soldiers of the immune system can be called upon for combat. The MHC is so essential that the olfactory cues reflecting the genetic compatibility among two individuals are thought to be based off of it alone.

Mate choice is influenced by MHC diversity through olfactory cues. MHC–peptide complexes present at the cell surface carry information about our cellular genetic make-up. When these complexes are shed from the cell surface they dissolve in our bodily fluids. This releases the peptide ligand component of the complex, which is then free to interact with other receptors (such as olfactory sensory neurons). The relevance of this has to do with the patterns of sensory neuron activation, which are unique to the structure of distinct peptide ligands. A person's distinct body odor reflects their MHC genotype, (drum roll) thus allowing us to assess the genetic compatibility of prospective mates!

This is where contraceptive pills come into play: natural selection has played a large role in making sure individuals with similar genetic material - siblings, for instance - do not breed because the resulting offspring will have weaker immune systems and be more likely subject to a whole suite of genetic faults. The cost of mating with someone who has a similar set of MHC alleles is large for the same reason. The idea is that with lots of diversity in our MHC genes, the body is ready to take on a lot of different invaders. This diversity can only be maintained by sexual outbreeding which leads to different combinations of MHC alleles representing a richer defense strategy.

Then the brilliant stinky t-shirt experiment was conceived:

In summary, (naturally cycling) women found the odors of MHC-dissimilar males more pleasant. These results yielded a negative correlation between number of shared alleles and pleasantness ratings.

Note, however, this test examined the preference of exclusively normally cycling women. When the same sweaty t-shirt test was performed on women who are taking contraceptives they found surprising results. These women didn't show a preference for the scent of males with dissimilar MHC genes. In fact, these women showed a higher preference for males with MHC genes similar to their own. If your body believes you to be in a pregnant state, this odor preference could be advantageous. Our primitive brains yearn to be surrounded by genetic similarity (ie. relatives) during this stressful and dangerous part of our life cycle.

Past studies suggest there are consequences to females preferring genetically similar males as long-term partners. Couples with dissimilar MHC genes are more satisfied and more likely to be faithful to their mate. Those who have similar MHC genes report less satisfaction and more wandering eyes. There are also fertility problems encountered by MHC-similar couples, who have a much higher probability of recurrent spontaneous abortions (RSA). There have also been studies that highlight the importance of odor perception as it plays a significant role in maintaining attraction within relationships.

So if a female acquires her male counterpart after beginning the pill, what happens when the woman goes off of it? Something I personally will never know. I'll take my sweaty man stench without the extra hormones, please.

Thornhill, R., Gangestad, S. W., Miller, R., Scheyd, G., McCollough, J. K., and M. Franklin. Compatibility complex genes, symmetry and body scent attractiveness in men and women. The Research & Education Division of The Fragrance Foundation.

Havlicek, J. and S. Roberts. 2009. MHC-correlated mate choice in humans: A review. Psychoneuroendocrinology 34: 497 - 512.

Sunday, August 23, 2009

The adaptive benefits of producing non-functional sperm

Scientists were scratching their heads while looking for the evolutionary explanation as to why the males of a butterfly species possessed predominantly non-fertile sperm.

What the heck is going on?

(image source)

Promiscuous mating regimes are great to research if you're interested in the coevolutionary arms race between male and female reproductive interaction. Usually it is evident that males will have evolved to manipulate female receptivity and females to resist the manipulation. An interesting example lies in the green-veined white butterfly (Pieris napi). Male butterflies transfer fertile and non-fertile sperm to their female. The non-fertile sperm requires less energy to produce and is used because females possess a sperm-storage organ that, when full, switches off the receptivity of the female. This enforces female monogamy because she cannot successfully mate with another male until she finishes the period during which she is not receptive (due to the full sperm storage organ). This period of time is called her refractory period.

However, females have also evolved to combat the standard lengthy refractory period by shortening it significantly. It is advantageous because it allows females to mate more and therefor have a higher reproductive output. Researchers found a positive genetic correlation between non-fertile sperm transfer and female refractory period. In other words, in the context of a promiscuous mating system, sexual conflict yeilds short female refractory periods and high proportions of non-fertile sperm in males. They also found that these traits were heritable and when the mating system was manipulated, the traits would also fluctuate.

This finding is consistent with previous findings related to male-female sexual conflict: selection on female reproductive traits directly affects male traits and vice versa.

Nina Wedell, Christer Wiklund, and Jonas Bergström. 2009. Coevolution of non-fertile sperm and female receptivity in a butterfly. Biology Letters.

Wednesday, July 22, 2009

Mating Systems 101

In a monogamous mating system, consistent pair bonds are formed between two individuals with sexual exclusivity. Polygamy is a general term used to describe a system in which an individual mates with 2 or more partners of the opposite sex. Two subsets exist within this definition. In a polygynous system, one male mates with two or more females. In a polyandrous system, one female mates with two or more males.

Polygynandry is a mating system defined by the sexual sharing among two or more females and two or more males. This term is often used interchangeably with promiscuity, but it differs because pair bonds form among specific individuals. In a promiscuous regime, no pair bonds are formed.

Across the board, mating systems develop to optimize the reproductive success of individuals. Monogamy will prevail when it is most fitness enhancing for those involved. For example, if females are dispersed, which is the case in some mammal and many bird species, monogamy will likely be the dominant strategy observed. If females are forced into a small area, such as female elephant seals cramped along a shoreline, males will use the opportunity to sequester females and maximize their reproductive output.

Monogamy will also prevail if the fitness of the offspring is dependent upon biparental care. In many bird species, the male and female are both fully capable of incubating the eggs and feeding hatchlings. If only one parent is involved, the probability of the chicks’ survival is compromised. Female-enforced monogamy is when a female eliminates the risk of other competing females from copulating with her chosen mate. A deep-sea angler fish male is born as a small, helpless sperm packet who lacks a digestive system and is entirely dependent upon his destine host female. He swims though the deep ocean in search of her, and has specialized mouth parts that assist in him in his permanent attachment to her.

Polygyny is by far the most commonly observed mating system in Animalia, and its presence is based on the extent to which males can monopolize females. This model applies to species in which the territory of a male contains useful resources for the female and her offspring. The environment plays a significant role in this mating system because females are easier to sequester when resources are spatially clumped. For example, female elephant seals in the Falkland Islands typically rear offspring and feed along the shoreline. Males fight one another in an effort to establish a more dominant hierarchy ranking which allows them access to the largest territory of shoreline. Once established, he is considered a harem holder, and mates with all the females who nest in his territory (a heram group). In polygynous mating systems, male reproductive success is a function of pre-copulatory strategies such as fighting in the example above. Males aim to mate with as females as possible, and females choose the male based on the quality of the territory he protects. A very small percentage of alpha males are successful harem holders among polygynous populations. The remaining male elephant seals roam the periphery of the territories, and are called satellite males.

Polyandry has been considered an evolutionary problem because it was thought to challenge one of the major underpinnings of sexual selection. It is the assumption that the disparity between male and female gamete investments (anisogamy) has favored the selection for diverging mating habits between males and females. Females are thought to be the “choosier” sex because they invest more energy into generating eggs, while males tend to favor quantity over quality and their fitness will not be lowered if they mate with a female of low genetic quality.

This line of thinking has gone under extreme scrutiny recently, as there has been accumulating molecular evidence revealing multiple paternity (polyandry) to be a common practice in animals. Multiple hypotheses have developed to explain this. The material benefits hypothesis predicts females who mate with more than one male are privileged to access more resources, parental care, and a limitless sperm supply. The genetic benefits hypothesis broadly predicts females who are mated with multiple males will produce offspring who are the result of superior ejaculates. If the offspring are males, they potentially have the same high quality sperm and will be able to heighten the fitness of the mother.

There are unique cases that do not fit in the categories described above. For example, we see an investment role reversal in Red Phalaropes of Alaska. Females exhibit traditionally masculine qualities. They are bigger and more colorful than males and play no role in incubating or caring for the young. The female spends about a week courting a single male and laying her eggs in his nest. Females of this species are able to generate eggs quickly, and after a week the female begins searching for another mate. Males incubate the eggs and nurture the chicks alone.

Polygynandry and promiscuity are similar yet distinctly different mating systems. Polygynandrous females regularly form pair bonds and copulate with several males at the same time as males form pair bonds and copulate with several females. The polygynandrous European badger lives in social groups with as many as five mothers and five fathers that produce multiple-paternity litters. It is thought the primary reason for this is described by the resource dispersion hypothesis: polygynandrous groups may arise because limited optimal resources may force more than one breeding pair within a territory. There is usually a dominant pair and a number of subordinates within a social group. In some species the subordinates do not mate, but in many cases subordinate females produce litters of mixed paternity.

Promiscuous species are those in which pair bonds do not form and males and females are likely to copulate with more than one individual of the opposite sex. It is a unique system because subordinate males have the opportunity to access females and male reproductive success is a function of post-copulatory strategies such as sperm competition and cryptic female choice. For example, when brown headed cowbirds live in areas with abundant resources, territorial lines are not well defined and promiscuity is often reported. The brown headed cowbird is a nest parasite that lays its eggs in other birds’ nests and provides no parental care for its young. Promiscuity may be the obvious choice given the birds’ behaviors and their lack of parental care.

Tuesday, July 14, 2009

Traumatic Insemination in aptly named 'Harpactea sadistica' spider

A violent but evolutionarily effective mating strategy has been spotted in spiders from Israel. Males of the aptly-named Harpactea sadistica species pierce the abdomen of females, fertilising their eggs directly in the ovaries. This has been described as a "traumatic insemination strategy," in which insemination wounds are created by male genitalia in areas outside the genital orifice of females. It is practiced because it gives the first male a reproductive advantage by bypassing structures in the females' genitalia.

These tactics have been observed in insects such as mites, bedbugs, and flies, but this study was the first time that it was documented in spiders. Typically, spider males deliver their genetic package via sperm that manually inserted using a pair of appendages called pedipalps.

The sperm are then held in a receptacle between the ovipore and ovary known as a spermatheca until an egg is released. However, the spermatheca is a "last in, first out" structure, so that if any further males inseminate a female, the last mate's sperm is the first in line to fertilize an egg.

Milan Rezic, an entomologist at the Crop Research Institute in Prague, has spotted a spider circumventing this problem by delivering sperm directly to the ovaries via holes that the males bore directly in the females' abdomens. The male possesses a pair of emboli, appendages modified for piercing females.

The way in which the male H. sadistica inseminates the female is choreographed and complex. The male taps the female, subdues her, and wraps himself around her to properly position the sex organs. He then alternates between the two organs, piercing and injecting the sperm on one side, then the other. The physical marks left are two neat rows of holes in her abdomen.

An analysis of the females of the species has shown that relative to other spiders, their spermathecae are atrophied, or shrunken. In an apparent case of co-evolution, they seem to be slowly shrinking into nonexistence now that their purpose is being bypassed by the males' more direct approach. This is yet another example of the co-evolutionary arm's race we see between many male and female species, in which males evolve to more efficiently inseminate the female and displace other males' seminal fluid, and females evolve to be able to control who inseminates her precious eggs.

Dr. Rezac foresees the race continuing. He suggests that a means to avoid the injury caused by the males might drive the evolution of secondary genitalia nearer to the ovaries, which have been observed in some spiders and butterflies.

Rezac, M. 2009. The spider Harpactea sadistica: co-evolution of traumatic insemination and complex female genital morphology in spiders. Proceedings of the Royal Society: Biological Sciences 276(1668):2697-701.

Sunday, May 24, 2009

When most fertile, females choose the jerk

This paper, entitled "Changes in Women’s Mate Preferences Across the Ovulatory Cylce," examined how women rated men displaying certain characteristic indicators of good genes and good investment throughout their ovulatory cycle. First, a sample of women rated men based on the following traits and characteristics: “intelligence, warmth, degree of social respect, ability to be a good father, sexual faithfulness, capacity for financial success, physical attractiveness, muscularity, confrontativeness with other men, and arrogance." The men participating in the study as subjects also rated themselves based on these characteristics. Next, a different sample of women rated the attractiveness of each man as a long-term or short-term mate.

Their hypothesis questioned if mate preference varies depending upon where the woman is in her ovulatory cycle. They predicted that women would prefer good gene indicators when they are most fertile and good investment indicators in other contexts.

These indicators are important from a female perspective for a number of reasons. Females are capable of yielding a limited number of gametes in her lifetime. Gestation and lactation are also incredibly energy-consuming and required years of commitment before a woman is able to mate again to successfully rear another child. For these reasons, it is argued that women are the choosier sex.

Examples of good gene indicators are those phenotypes that correspond to good health and developmental stability. Particularly when women seek partners as short-term mates (ahem one night stands), it is predicted that she would prefer indicators of heritable fitness, or genes that will most likely yield successful offspring. Facial symmetry and masculinized physical features are examples of good gene indicators. They reflect good health and high testosterone levels, respectively. From an evolutionary standpoint, these indicators are advantageous because they will lead to fitness-enhancing characteristics passed on to the next generation.

They recognized that some traits, namely paternal investment indicators, had not been tested to empirically support the hypothesis that fluctuation in female preference does not extend to traits such as warmth, kindness, and faithfulness. They hoped to examine a wider variety of physical and behavior characteristics in men that serve as indicators of good genes and good investment.

Women’s ratings of men’s attractiveness were analyzed using a multilevel regression. The analysis described how women’s attraction to men as long-term or short-term mates related to the men’s characteristics (that both sexes were able to identify). They found that nine out of ten male traits were more preferred in the context of choosing short-term mates rather than long-term mates, including arrogance, muscularity, confrontativeness, etc.

They also analyzed women’s preferences for male characteristics as it relates to their degree of conception risk. In other words, they were looking for characteristics of men that women found attractive when they were most fertile, or at risk of producing a conceptus. They did find significant evidence that women preferred six traits of men for short-term mate interactions more when they were most fertile! These traits include confrontativeness, arrogance, muscular physical features, social respect, and physical attractiveness.

This supports the notion that women’s mate preferences predictably shift throughout their ovulatory cycle. When they are most fertile, women tend to preference indicators of good genes.

When they tested for fluctuations in female preference for long-term mates in good parental investment indicators across the ovulatory cycle, they found none. Women did not prefer parental investment mate qualities more when they were ovulating than when they were not.

These findings provide further support for the good genes hypothesis, which predicts women will prefer indicators of heritable genetic quality more when they are most fertile and assessing men as short-term mates.

Gangestad, S. W., Garver-Apgar, C. E., Simpson, J. A., and A. J. Cousins. 2007. Changes in Women’s Mate Preferences Across the Ovulatory Cylce. Journal of Personality and Social Psychology 92(1): 151-163.

Tuesday, May 12, 2009

High emotional intelligence linked with high orgasm frequency

According to a study in the Journal of Sexual Medicine, "variations in emotional intelligence--the ability to identify and manage emotions of one's self and others--are associated with orgasmic frequency during intercourse and masturbation."

In short, the study found:

Emotional intelligence was not associated with ... age and years of education, nor did we find a significant association between emotional intelligence and potential risk factors for [female orgasmic disorder] FOD such as age, body mass index, physical or sexual abuse, or menopause. We found emotional intelligence to be positively correlated with both frequency of orgasm during intercourse ... and masturbation .... Women in the lowest quartile of emotional intelligence had an approximate twofold increased risk of infrequent orgasm ... Low emotional intelligence seems to be a significant risk factor for low orgasmic frequency. Consideration of this behavioral risk factor may need to be incorporated into research into FOD and possible treatment approaches.

This is interesting, and probably a valid finding in that it appears to be statistically demonstrable that there is a correlation between measured emotional intelligence and orgasm frequency. The correlation is positive, modest (between 0.13 and 0.23 Spearman's, and confirmed with logistical regression), and statistically significant.

They also found through a study using matched pairs of twins a statistically significant difference in both emotional intelligence measured by standard tests and patterns of orgasm frequency.

A worthy consideration with which to read this article is that contributers to emotional intelligence come from both environmental and genetic variables. To assume this correlation is entirely due to genetics is presumably not entirely true.

Original Source:

Burri, A., Cherkas, L., & Spector, T. (2009). Emotional Intelligence and Its Association with Orgasmic Frequency in Women Journal of Sexual Medicine DOI: 10.1111/j.1743-6109.2009.01297.x

Sunday, May 10, 2009

Homosexual and masturbatory behavior observed in flour beetles

This behavior in the 0.13-inch-long (three-millimeter-long) Tribolium castaneum, which can be found infesting flour in most temperate areas, has been observed for decades

They found that homosexual encounters did not improve a male's sexual success with females, as measured by the number of offspring carrying his genes. There was also no connection between homosexual activity and social dominance—male beetles that had many sexual encounters with other male beetles did not earn more attention from females.

What the team did find was that males were dribbling sperm onto each other. This suggested that males might be trying to get rid of old sperm, lining up fresher sperm for their next female encounter.

The team also found that if one male leaked semen on another male and the semen-covered male later bred with a female, the female's eggs could become fertilized with the sperm of the male she had never encountered. That a male could inseminate a female without directly breeding with her came as a big surprise.

It reveals that the flour beetles' homosexual behavior yields a direct reproductive benefit, allowing males to inseminate females without expending time or energy having sex with them.
"We could not believe these results when we first saw them, so we ran the experiment over and over again to make sure it was actually happening," Lewis said.

Levan, K. E., Fedina, T. Y.; Lewis, S. M. 2009. Testing multiple hypotheses for the maintenance of male homosexual copulatory behaviour in flour beetles. Journal of Evolutionary Biology. 22(1):60-70.

Same-sex mating observed in fungal species

Cryptococcus neoformans is a major cause of fungal meningitis in predominantly immunocomprised individuals.

Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions, especially between α isolates. Whether same-sex mating occurs in nature and contributes to the current population structure was unknown.

In this study, natural αADα hybrids that arose by fusion between two α cells of different serotypes (A and D) were identified and characterized, providing definitive evidence that same-sex mating occurs naturally. A novel truncated allele of the mating-type-specific cell identity determinant SXI1α was also identified as a genetic factor likely involved in this process.

In addition, laboratory-constructed αADα strains exhibited hybrid vigor both in vitro and in vivo, providing a plausible explanation for their relative abundance in nature despite the fact that AD hybrids are inefficient in meiosis/sporulation and are trapped in the diploid state. These findings provide insights on the origins, genetic mechanisms, and fitness impact of unisexual hybridization in the Cryptococcus population.

This study provides the first evidence of this and sheds light on the genetic and environmental factors that play important roles in the evolution of the current population structure of this pathogenic fungus.

Lin X, Litvintseva AP, Nielsen K, Patel S, Floyd A, et al. (2007) áADá hybrids of Cryptococcus neoformans: Evidence of same-sex mating in nature and hybrid fitness. PLoS Genet 3(10): e186. doi:10.1371/journal.pgen.0030186

Thursday, April 30, 2009

Ugly Bugs!

I sort of stumbled upon the Oklahoma Microscopy Society's Ugly Bug Contest Homepage.
What a discovery!
Check it out: The 2007 Winners

Saturday, April 25, 2009

Flora and Fauna Photography

These were taken during my recent trip to Key Biscayne, FL. 

Portuguese Man-O-War

Tricolored (Louisiana) Heron

Northern green anole 

Sunday, April 12, 2009

Volcano Eruption in Galapagos National Park

La Cumbre volcano in the Galapagos Islands started spewing lava, gas and smoke on the Fernandina Island. The most recent volcanic activity on Fernandina Island occurred in May 2005. I was fortunate to attend a course that focused on the biology and evolution of the Galapagos last summer - I never stepped foot on Fernandina because my group explored the eastern portion of the archipelago.

It still breaks my heart that this eruption may have a detrimental effect on the wildlife endemic to the island. The following excerpt was taken from the Glob Gazette News Blog.
In a statement it said the eruption is not a threat to people living on nearby Isabela Island. But it added that lava flowing to the sea will likely affect marine and terrestrial iguanas, wolves and other fauna.

The iguanas we encountered on the islands were unlike any reptile I've ever seen. They also were oblivious to our presence - or mildly annoyed at worst.

This picture (left) features the Galapagos marine iguana. One of their interesting and diagnostic features was the little white cap that each wore atop their heads. Due to the high salt content in their diets, they have evolved a mechanism to maintain an internal osmotic equilibrium. They sneeze to expel excess salt from salt glands that are located above the eye. This in combination with the wind results in an accumulation of white salt on their head. When I was in the Galapagos, an ongoing pursuit among group members was to photograph a marine iguana mid- sneeze, as they expelled excess salt every few minutes. Sadly, no one was successful. I will say that there is nothing cuter than a sneezing iguana.

The majority of land iguanas we saw were on Santa Fe Island. They were visible because the island had low-growing vegetation that surrounded a sparsely distrubuted Opuntia cactus forest. 

The land iguanas were quite visible, startlingly large, and usually munching on yellow purslane flowers (Protulaca lutea).

I hope the population of critters who were affected by the recent eruption are able to quickly rebound. I don't know the impact's severity at this point, but I can't say enough about the importance of conserving the Galapagos Archipelago. It represents a thriving pristine wilderness as untamed territories elsewhere - everywhere - are increasingly being forced to share resources with fatal human co-inhabitants. 

Saturday, April 11, 2009

Wishing you a Joyous Estrus!

This here is informative. Thanks Tom Riddering from MN Atheists.

Quick! What do eggs, flowers, the East, maidens dancing around phallic symbols, the vernal equinox, fecund rabbits, chicks, flowers, Mardi Gras, estrus cycles, and Christianity all have in common? SEX!

Well, Christians actually call it Easter, named after Eastre, the Germanic fertility goddess, which comes from the same origin as the word "east." Why east? That's where the sun rises! The same spring sun that shines on those brightly colored chicken ova and brings new life to the earth -- flowers, chicks, bunnies, and the occasional god. Jesus wasn't the only god allegedly reborn around the vernal equinox. There was also Adonis, Osiris, Perseus, and Orpheus.

Spring is when we have the licentious festivals of Mardi Gras, Carnival, and the ancient Roman fertility festival of Lupercalia. It's when the Kanamara Matsuri (Festival of the Steel Phallus) is celebrated in Japan. Nothing subtle about those Buddhists and Shinto! It's when pre-Christian pagans all over the earth celebrated the return of life after the dark death of winter and propitiated their gods for a successful growing season by celebrating their fertility. The early Christian church couldn't eradicate this popular festival, so they hijacked it and assigned new theological meaning to it. But under all that sanctimonious piety, Easter is nothing but the spring fertility rites. Now that's something even atheists can celebrate!

Tuesday, April 7, 2009

David Attenborough: Evolution from Sea to Land

Monday, April 6, 2009

How to Define an Open Mind

"Science promotes and thrives on open-mindedness because the advancement of our understanding about the reality in which we exist depends upon our willingness to accept new ideas."

Friday, April 3, 2009

Temperature-dependent Sex Determination in Humans!?

This is some wonderfully strange new research. Girls are more likely to be born at tropical latitudes than in temperate or subarctic climates. This study provides the first global look at human sex ratios and could shed light on how temperature and day length influence human reproduction. This article reminded me of temperature-dependent sex ratio of reptiles, and I'm not at all surprised that the length of day and temperature would induce a change in sex ratio.

Strangely, in reptiles there is polar variation in the effect temperature has on the outcome of the offspring among taxonomic groups. In crocodiles and alligators, for example, eggs incubated in temperatures below 30 °C produce female offspring and eggs incubated above 34 °C produces male offspring. In turtles, however, at cooler temperatures ranging between 22.5°C and 27 °C mostly male turtles are produced and at warmer temperatures, around 30°C, only female turtles arise. Many other animals adjust the sex of their offspring based on environmental cues such as temperature, but to confirm whether humans do to some extent is difficult to measure. There are multiple variables that have been confirmed to also affect the human sex ratio, such as stress imposed on the mother during pregnancy. How would one overcome this obstacle?

Reproductive endocrinologist Kristen Navara of the University of Georgia in Athens analyzed global sex ratios over 10 years, enough time to be sure that short-term social or economic crises weren't driving the results. Navara had previously found that Siberian hamsters raised with fewer hours of daylight produced more male offspring, and she wondered if the same might be true for humans. Navara gathered sex ratio data for every nation within a decade of uninterrupted statistics. She then analyzed the figures from 202 countries based on latitude, average temperature, day length, and socioeconomic status.

She found that humans living in areas with long, dark winters have more boys: 51.3% of babies born in temperate and subarctic regions are male, compared with 51.1% in the tropics. No one knows exactly when or how sex selection happens, but Navara says that some animals skew sex ratios as early as fertilization. "I suspect that all of this has something to do with melatonin," a hormone that regulates sleep-wake cycles and the production of female reproductive hormones, says Navara, noting that melatonin release varies in response to day length and season.

Navara, Kristen J. 2009. Humans at tropical latitudes produce more females. Biology letters.

Sunday, March 22, 2009

Sex bias is entirely controlled by the females in Gouldian Finches

The birds, which have either red or black heads, prefer to mate with males with the same head colouring, as this signifies a better genetic match. A report in the journal Science says that the birds compensate for this by having more male chicks in their brood. Colourful Gouldian finches can judge if a mate is genetically compatible just by looking at its head.

This new study has found that, when the female finches mate with a male that has a different head colour, they select the sex of their offspring - giving their chicks a better chance of survival.
Two male Gouldian finches

In birds, the sex of an egg is already determined before it is fertilised by the male.
Sarah Pryke, a biologist from Macquarie University in Sydney, led this study. She found that when female finches mate with mismatched males, 70% of their chicks are male.

Dr Pryke's team disguised some of the male finches to show that this "sex bias" is entirely controlled by the females. They blackened the head feathers of red males, using a non-toxic dye, and paired them to both red and black females to allow them to breed.

The birds were fooled, and the team found that black females that mated with the "disguised" red males produced an equal ratio of male and female chicks. "This is the clearest and perhaps most extreme example of sex biasing that has been found," said Dr Pryke. "It's really black and white - or in this case black and red."

"It is pretty amazing to think that the female herself has so much control - subconsciously of course - over this basic physiology," said Dr Pryke.

The results were particularly striking because colour-matched matings, which result in much healthier broods, always produce roughly equal numbers of male and female chicks. "Females really don't want to mate with a male with a different head colour. But there simply aren't enough compatible males, so later in the mating season they seem to use this control to make the best of a bad situation."

From BBC News

Thursday, March 19, 2009

The Fish-Tetrapod Transition

With the vertebrate comparative anatomy lab quickly approaching in my Animal Diversity class, I was excited to fall upon a paper that appears well-tailored to the content of my own teaching schedule (for once! geesh). This is spankin' new, published March 17, 2009, from the journal Evolution: Education and Outreach.

This paper is paricularly interesting because it outlines both the history of tetrapod evolution and the history of human's perception of the animal transition from aquatic to terrestrial habitats. It highlights the helpful fossils unearthed that helps us trace this vertebrate history, such as Icthyostega spp., and those fossils, such as the Eryops cephalus, that hindered the pursuit. In the case of the latter organism (pictured below), despite its anatomy being characteristic of an early trasitional tetrapod, its ancestral origin was found to exist much later in tetrapod evolution.

This paper also describes the reason for the recent fame of the Tiktaalik transitional fossil, as it is known from several nearly complete specimens. Its excellent preservation and diagnostic transitional tetrapod features have made it an important tool for understanding the origin of the phylogenetic tree of Tetrapoda.

"In a nutshell, the 'fish–tetrapod transition' usually refers to the origin, from their fishy ancestors, of creatures with four legs bearing digits (fingers and toes), and with joints that permit the animals to walk on land. This event took place between about 385 and 360 million years ago toward the end of the period of time known as the Devonian. The Devonian is often referred to as the 'Age of Fishes,' as fish form the bulk of the vertebrate fossil record for this time."

This paper is a great read for eager young biologists like myself searching for readable scientific papers on phylogenetics and evolution. I recommend it!

The Fish–Tetrapod Transition: New Fossils and Interpretations

Monday, March 16, 2009

More Coleopterans Coitus

Seed Beetle 1.jpg

A new study has revealed the painfully scandalous anatomy of C. maculatus seed beetles. The C. maculatus have a series of spikes and barbs on their members that, during sex, become embedded in their mates, acting as anchors of sorts.

Seed beetle 3.jpg

"They literally injure females internally in their copulatory duct. They're pretty mean," Goran Arnqvist, the lead author of the study, said to National Geographic.

After looking at a large group of diverse, virgin beetles after copulation the study concluded that the beetles with the "largest and most damaging" phalluses had the most reproductive success. The injury to the females was simply an "unfortunate side effect" of the process.

At this point, I will use what little class I have to bite my tongue.

Seed beetle 2.jpg

Seed beetle 5.jpg
Above: a seed beetle's jaw-like spine structure on its appendage.

Tuesday, March 10, 2009

A Sea Biscuit's Life

I'm teaching about Echinoderms this week in Animal Diversity lab. They exhibit pentaradial symmetry as adults, but are actually born with bilateral symmetry. Put a beat to that concept, and you have a dance party (below).

A Sea Biscuit's Life from Bruno Vellutini on Vimeo.

Friday, March 6, 2009

Sand lizards find excuse for being lazy lovers

Sand lizards engage in what are called serial copulation events. A single female copulates with multiple males in a sequence: male one, male two, male three, etc. In response to selective pressure exerted by mating with more than one male, the first male will insert a copulatory plug to serve as a barrier so the next male's sperm does not fertilize his female. We see this elsewhere in Animalia - namely, in humans! (Think "flowback")

Scientists noticed something peculiar was resulting from the serial copulation events. Sand lizards yield a disproportionate number of offspring that are sired by the multiple partners with whom the female mates. We would expect that the first male sire the majority of offspring, but that was not the case. There appeared to be something going on with the sperm or reproductive tract, but what?

Mats Olsson of University of Wollongong observed the male lizards exerting variable amounts of effort when copulating with a female. The amount of effort was positively correlated with clutch size (Figure 1 and 2, above). He sought to find what determined the time investment.

He and his team studied the second male and his ejaculation tactics. The second male would approach a female and obtain information about the prior male's relationship to her. If his rival was more genetically similar to the female than the second male was to the female, the second male stands a better chance of passing on his genetic material. The male sand lizards are able to sense an MHC (major histocompatibility compex)- related odor of the copulatory plug. With this information, the second male could ascertain the relatedness of the first male and female, and would spend more time in copula with the female if the first male was more related to her than he was to her. (Figure 3, below)

If his nemesis was less related to the female than the second male, the second male would engage in an informal "quickie" and then move on.

Olsson, M., T. Madsen, B. Ujvari, and E. Wapstra. 2004. Fecundity and MHC affects ejaculation tactics and paternity bias in sand lizards. Evolution 58: 906-909.

Pepto-Bismol-Pink Dolphin in Louisiana

This is a peculiar find. (Thanks to Dr. Melissa Palmer for the tip)

Pink the albino dolphin: Pink dolphin appears in US lake

The pink color and reddish eyes indicate albinism, an inherited condition that results in individuals lacking normal pigmentation. This special aquatic mammal drew quite a crowd when it first surfaced in Lake Calcasieu, an inland saltwater estuary north of the Gulf of Mexico in Louisiana.

The dolphin was first identified by charter boat captain Erik Rue, who said it was swimming with a pod of four other dolphins. I hope this special critter makes it despite its strange coloration.

Is this first pink dolphin observed in nature?

Actually, there are pink dolphins that reside in South America in the Amazon. The boto is the largest of the river dolphins. They have different color patterns, varying from bright pink to deep grey, depending upon their age and the geographical area where they are found. In the Arauca River in Colombia, dolphins are very pink (pictured below) and very active at the surface. They tend to become more "pink" with age because their skin becomes more translucent and the blood circulating beneath their skin becomes visible. These Amazon River Botos are close relatives to the dolphins with which we are familiar from the states. However, there are a few significant morphological differences.

In addition to the higher frequency of pink coloration among populations, the Amazon River Botos have specialized teeth that are used to crush fish and heavily armored benthic organisms such as crustaceans. They also have a big hump on their head and a ridge on their back in place of a defined dorsal fin.

da Silva V (1994) Aspects of the biology of the Amazonian dolphins Genus Inia and Sotalia fluviatilis. PhD Dissertation, University of Cambridge, Cambridge, 327 pp.

Tuesday, March 3, 2009

Science Fare

A student introduced me to this fine tribute to science. Bad Astromony guy, you inspire!

In April, I was asked to give a short speech to a group of local students who participated in a science fair. I wasn’t sure what to say to them, until I saw a newscast the night before the fair. The story was some typically inaccurate fluff piece giving antiscience boneheads “equal time” with science, as if any ridiculous theory should have equal time against the truth.

I sat down with a pad of paper and a pencil and scribbled down this speech. I gave it almost exactly as I wrote it.

I know a place where the Sun never sets.

It’s a mountain, and it’s on the Moon. It sticks up so high that even as the Moon spins, it’s in perpetual daylight. Radiation from the Sun pours down on there day and night, 24 hours a day — well, the Moon’s day is actually about 4 weeks long, so the sunlight pours down there 708 hours a day.

I know a place where the Sun never shines. It’s at the bottom of the ocean. A crack in the crust there exudes nasty chemicals and heats the water to the boiling point. This would kill a human instantly, but there are creatures there, bacteria, that thrive. They eat the sulfur from the vent, and excrete sulfuric acid.

I know a place where the temperature is 15 million degrees, and the pressure would crush you to a microscopic dot. That place is the core of the Sun.

I know a place where the magnetic fields would rip you apart, atom by atom: the surface of a neutron star, a magnetar.

I know a place where life began billions of years ago. That place is here, the Earth.

I know these places because I’m a scientist.

Science is a way of finding things out. It’s a way of testing what’s real. It’s what Richard Feynman called "A way of not fooling ourselves."

No astrologer ever predicted the existence of Uranus, Neptune, or Pluto. No modern astrologer had a clue about Sedna, a ball of ice half the size of Pluto that orbits even farther out. No astrologer predicted the more than 150 planets now known to orbit other suns. But scientists did.

No psychic, despite their claims, has ever helped the police solve a crime. But forensic scientists have, all the time.

It wasn’t someone who practices homeopathy who found a cure for smallpox, or polio. Scientists did, medical scientists.

No creationist ever cracked the genetic code. Chemists did. Molecular
biologists did. They used physics. They used math. They used chemistry, biology, astronomy, engineering. They used science.

These are all the things you discovered doing your projects. All the things that brought you here today.

Computers? Cell phones? Rockets to Saturn, probes to the ocean floor, PSP, gamecubes, gameboys, X-boxes? All by scientists.

Those places I talked about before? You can get to know them too. You can experience the wonder of seeing them for the first time, the thrill of discovery, the incredible, visceral feeling of doing something no one has ever done before, seen things no one has seen before, know something no one else has ever known.

No crystal balls, no tarot cards, no horoscopes. Just you, your brain, and your ability to think.

Welcome to science. You’re gonna like it here.

Parasitizing caterpillar tricks ants into service

A kind of European caterpillar can garner royal treatment from ants by mimicking the ch-ch-ch-ch of their queen, says an international research team.

Ants of the species Myrmica schencki can be fooled into carrying certain caterpillars into the colony nurseries where the fakers enjoy full care and five-star dining, explains Jeremy Thomas of the University of Oxford in England. An interloper caterpillar gains most of its body mass while luxuriating in ant care, and then turns into a Maculinea rebeli butterfly.

Chemical camouflage alone will let the caterpillars game their way into the ant colony. Now experiments show that the noises the caterpillars make get them the premium treatment, Thomas says. The rhythmic caterpillar purring has the effect of the queen ant’s noises, not those of a worker, Thomas and his colleagues report in the Feb. 6 Science.

It’s news that a queen sounds different from workers in an ant colony, Thomas says. Ants have such remarkable chemical messaging systems that their noises haven’t received much scientific attention.

“I haven’t been this excited about a paper in a long time,” says tropical butterfly ecologist Phil DeVries of the University of New Orleans. He made the first recordings of caterpillar calls, which he says occur only in groups that have some kind of relationship with ants.

M. rebeli caterpillars make a mini version of the brrrrrr of a woodcock or snipe, Thomas says. Recent work has suggested that caterpillar noises may come from repeated muscle spasms. And when caterpillars become enclosed pupae, they make noises by rubbing a scraper, or plectrum, on their abdomen against a patch of fine grooves called a file. “Actually they can wriggle their abdomen quite a bit,” Thomas says.

Adults of four of the 11 ant subfamilies also make noises by rubbing plectrum and file, Thomas says. “It’s rather like strumming a guitar.” In a quiet room of ants, he can just manage to hear “quite a scratchy sound,” he says.

Advances in miniature electronics made the new study possible. Specially built ant-scale microphones and speakers allowed researchers to record both queen and worker ants under normal conditions and then play back the noises and observe ant behavior.

To a human ear, queens and caterpillars don’t sound at all similar, Thomas warns. Yet ants perceive noises differently, picking up vibrations with sensors in the legs. “There is a debate about how well, if at all, they perceive airborne sounds,” he says.

Thursday, February 26, 2009

Alternative mating tactics and female mimicry as post-copulatory mate-guarding behavior in the parasitic wasp Cotesia rubecula

In species where there exists intense competition among males for females, we often see elaborate modification to what we would consider normal courtship to increase an individuals' chance of a successful copulation.

A peculiar example of this is seen in the solitary larval endoparasitoid of the cabbage white butterfly. The male parasite, Cotesia rubecula, displays post-copulatory female mimicry in the hopes of copulating with a desired female with whom he and another male are competing.

When the female is ready to mate, she exhibits a characteristic colulatory position by lowering her antenna (see graphic, Figure 2). This serves as a signal to males that she is ready to mate. If two males are present and competing for the same receptive female, it is not uncommon for "male one" to trick the other by assuming the same pre-colulatory pose. "Male two," confused and randy, may attempt to copulate with guised male one. Male one quickly unveils his identity by quickly scurrying over to the female and copulating with her, leaving a disapointed male two in his dust.

Though I have never observed this mating strategy among humans - and I can't say I think it would result in a sucessful copulation - it's a pretty clever behavior adaptation in a competitive intra-sexual environment.

Published in Animal Behavior

Monday, February 23, 2009

Flora and Fauna Photography

Redpoll, originally uploaded by amplexus.

This picture was taken in sub-zero temperatures as the sun rose in Two Harbors, MN.

Saturday, February 21, 2009

Sex Is Thirst-quenching For Female Beetles

ScienceDaily (Aug. 29, 2007) — Female beetles mate to quench their thirst according to new research by a University of Exeter biologist. The males of some insect species, including certain types of beetles, moths and crickets, produce unusually large ejaculates, which in some cases can account for around 10% of their body weight. The study shows that dehydrated females can accept sexual invitations simply to get hold of the water in the seminal fluid.

Dr Martin Edvardsson, whose research is published in the journal Animal Behaviour (August 2007), studied the bruchid beetle Callosobruchus maculatus, a serious pest in warmer parts of the world. Some females were given unlimited access to water while others were not. All females were free to mate with males and the study found that thirsty females mated 40% more frequently than those with free access to water.
Female bruchid beetles can absorb the water in the seminal fluid through their reproductive tracts and need to mate less frequently the more water they take from each mating. This is to a male's advantage because the longer the female goes without mating with another male, the greater his chance of successful fertilization. By transferring a large amount of water with the sperm, a male can help ensure his sperm has more time to fertilize the eggs without having to compete with the sperm from future matings. Dr Martin Edvardsson of the University of Exeter says: 'The large ejaculates may have evolved because males can make it less beneficial for females to remate by providing them with a large amount of water.'

From morsels of food to less useful offerings like dried leaves or balls of silk, insects' nuptial gifts are thought to perform the role of enticing a female to mate or investing in the resulting offspring. However, this study shows that males can also prevent females from mating with other males by giving them a valuable nuptial gift. Dr Edvardsson says: 'This research offers an alternative theory on the function of 'nuptial gifts', which are an important part of insect courtship and mating.'

Dr Edvardsson argues that the trade-off between the costs and benefits of mating is essential to the mating behaviour of female bruchid beetles. The males have spines on their genitalia that puncture the females' reproductive tract as they mate. Because of the damage this causes, females must carefully trade off the costs and benefits of mating, and limit the number of times they mate depending on their need for water and sperm.

Because there are always costs as well as benefits associated with mating, similar trade-offs are likely to be important in many species where males provide their mates with material resources. 'The key thing' says Dr Edvardsson 'is that the resource provided by males is less beneficial to females the more of it they already have, like water or food for example.'

Though Dr Edvardsson believes these findings may be relevant to many other animal species, he does not think the study has any implications for our understanding of sexual behaviour in all other animals. He concludes: 'This is unlikely to occur in say, mammals and birds, because it is impossible for a male to give a female a gift that would fulfill her needs for food or water for such a long period of time. Also, while many female insects can store live sperm inside for long periods of time, females of these species need relatively fresh sperm to fertilize their eggs.

Thanks, sciencedaily!

Friday, February 20, 2009

The Loom Science Tattoo Emporium

This is so adorable I can hardly take it.

The Loom Science Tattoo Emporium

When I find a passion that strongly wills me to ink myself, I aspire to be posted on that emporium, too.

Gay penguins steal eggs from straight couples

The two penguins have started placing stones at the feet of parents before waddling away with their eggs, in a bid to hide their theft.

But the deception has been noticed by other penguins at the zoo, who have ostracised the gay couple from their group. Now keepers have decided to segregate the pair of three-year-old male birds to avoid disrupting the rest of the community during the hatching season.

A keeper at Polar Land in Harbin, north east China explained that the gay couple had the natural urge to become fathers, despite their sexuality.

"One of the responsibilities of being a male adult is looking after the eggs. Despite this being a biological impossibility for this couple, the natural desire is still there," a keeper told the Austrian Times newspaper.

"It's not discrimination. We have to fence them separately, otherwise the whole group will be disturbed during hatching time," he added.

There are numerous examples of homosexuality in the animal kingdom, but gay penguins have captured the public's attention more than any other species.

A German zoo provoked outrage from gay lobby groups after attempting to mate a group of gay male penguins with Swedish female birds who were flown in especially to seduce them. But the project was abandoned after the males refused to be "turned", showing no interest in their would-be mates.

In 2002 a couple of penguins at a New York zoo who had been together for eight years were "outed" when keepers noticed that they were both males.

Found in the Weird News

Thursday, February 19, 2009

Richard Dawkins: Seven Wonders of the World (Parts 1-3)

(Could I BE more excited for his presentation at Northrop March 4th?)
Part 1. The Spider's Web

I think not...

Part 2. The Bat's Ear
The Digital Code

Part 3. The Digital Code Cont.
The Parabolic Reflector
The Embryo
David Attenborough

Thursday, February 12, 2009

Happy Birthday Darwin!!

Jim Cotner created this brilliant masterpiece.

I've listed some science events happening in/around the month of February below.

Other events going on this month?

1. LIFE: A Journey Through Time
Thursday, February 12, 2009, 7 to 9 p.m.

Bell Museum Auditorium
The event will feature top University biologists using Lanting's photographs as a springboard to deliver a rapid-fire presentations relating their research on evolution to the images. From the big bang to the human genome, hear the newestI theories on how life evolved and enjoy the North American premiere of one the world's most celebrated photography exhibits.

Keith Olive

Mark Decker

Sehoya Cotner

Greg Laden

Mark Borrello

Lynn Fellman

2. Cafe Scientifique: A Romance with Spiders
Tuesday, February 17, 2009, 7 p.m.
Bryant-Lake Bowl

Spiders, one of the most important terrestrial predators on the planet, are primarily solitary, often cannibalistic, and always voracious. However, one percent of spiders are highly social, living in large groups characterized by tolerance and cooperation. Even in the most social spider species, individuals must balance the benefit of group living and the strong compulsion to eat irritating siblings. Linda Rayor, a senior lecturer and senior research associate who teaches spider biology and insect behavior at Cornell University, will discuss how she came to combine romance with spiders and aspects of their unusual sex and predatory lives.

3. The Purpose of Purpose: A Lecture by Richard Dawkins
Wednesday, March 4, 2009, 7:00pm
(I just bought my tickets and I'm psyched! This fellow will surely be in your F1's textbooks)

Wednesday, February 11, 2009

Friday, February 6, 2009

"I'm a Neurosurgeon, and an Ignoramous"

A Neurosurgeon, Not A Darwinist

This commentary in Forbes really made me cringe. People can wave around their PhDs in whatever subject they like, but it does not protect them from being completely ignorant in another.

"The fossil record shows sharp discontinuity between species, not the
gradual transitions that Darwinism inherently predicts. Darwin's theory offers
no coherent, evidence-based explanation for the evolution of even a single
molecular pathway from primordial components"

Oh, wow! Is the Tiktaalik, who shares anatomical features with both primitive fish and the first tetrapods, mean nothing to this neurosurgeon? Or the fact whales have floating pelvic bones that are remnants of their tetrapod ancestry? Or the transitional archaeopteryx bird-reptile?!Or the long list of others that is far from complete...?

Above: Tiktaalik roseae

Wednesday, January 28, 2009

Bottlenose dolphin shows off her butchering skills

Rubbing the inkless corpse against the sand breaks and releases its indigestible cuttlebone. The filleted cephalopod is now ready to eat (Image: Julian Finn et al)

Considering they can't wield a knife or cleaver, dolphins make impressive butchers. Researchers in Australia recently observed a bottlenose performing a precise series of manoeuvres to kill, gut and bone a cuttlefish.

The six-step procedure gets rid of the invertebrate's unappetising ink and hard-to-swallow cuttlebone.

The procedure begins when the dolphin shoos a cuttlefish out of an algal forest into an open patch of the seabed. Next, she pins the cuttlefish down, ramming it into the ground. To rid the body of ink, she uses her snout to pick up the cuttlefish, and then shakes it several times until a black cloud streams out.

Let's walk through that again:

The dolphin begins the routine by shooing a cuttlefish out of hidingThe dolphin begins the routine by shooing a cuttlefish out of hiding (Image: Julian Finn et al)

She proceeds to pin it to the sand to kill it
She proceeds to pin it to the sand to kill it (Image: Julian Finn et al)

Next, she nudges the invertebrate off the seafloor with her snout
Next, she nudges the invertebrate off the seafloor with her snout (Image: Julian Finn et al)
To remove the cuttlefish's ink, which can slow digestion, the dolphin shakes it back and forth
To remove the cuttlefish's ink, which can slow digestion, the dolphin shakes it back and forth (Image: Julian Finn et al)

Rubbing the inkless corpse against the sand breaks and releases its indigestible cuttlebone
Rubbing the inkless corpse against the sand breaks and releases its indigestible cuttlebone (Image: Julian Finn et al)

The filleted cephalopod is now ready to eat!
The filleted cephalopod is now ready to eat (Image: Julian Finn et al)


Article from NewScientist