Chicken, archosaur…same difference

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My daughter is learning about evolution in high school right now, and the problem isn’t with the instructor, who is fine, but her peers, who complain that they don’t see the connections. She mentioned specifically yesterday that the teacher had shown a cladogram of the relationships between crocodilians, birds, and mammals, and that a number of students insisted that there was no similarity between a bird and an alligator.

I may have to send this news article to school with her: investigators have found that a mutation in chickens causes them to develop teeth—and the teeth resemble those of the common ancestor of alligators and chickens, an archosaur.

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The cephalopod sex series

As part of the ongoing migration to the new site, I’ve brought over some strangely popular articles: Tentacle sex, Tentacle sex, part deux, Squid nuptial dances, and Octopus sex. All across the world, people are wondering what the etiquette is if they should find themselves in a romantic situation with an amorous cephalopod, and it is my duty to provide the answers.

If only I’d thought of bringing these over last week, in time for Valentine’s Day. I hope no one made any beastly gaffes because they couldn’t find these articles in time…

Octopus sex

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I rather like this illustration I ran across in some reading. It’s a bit risqué, and reminded me of some ukiyo-e…the kind of thing you don’t usually expect to find in a biology journal.

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This line drawing was made from a photograph of a male H. lunulata (shaded) copulating with a female. The arrow points to the male’s hectocotylus, which is being inserted into the female’s mantle cavity.

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Tentacle sex, part deux

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When male squid get together with their female friends, they have a couple of nuptial options: they can go ahead and use their charm to court the female, or they can just start poking her with tentacles full of sperm in mating frenzy. Now some of you guys might be thinking the latter option sounds good (what’s the point of living the life of a squid if you can’t be selfish and uninhibited, right?), while the ladies and gentlemen here might think the former is better. A study of the mating behavior of squid close-up and in the lab suggests that it’s true: taking one’s time and mating cooperatively is much more likely to get the sperm in the right place and improve the likelihood of reproductive success. And as a bonus it’s got some lovely photos of squid caught in flagrante.

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Squid nuptial dances

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Yesterday’s [21 November 2005] post about squid had a most unsatisfying conclusion, so I feel compelled to mention two things: squidblog has a brief explanation of squid jet propulsion, and I’ve dug up another older paper on squid movement. Even better, it’s about squid nuptial dances and mating.

Here, see? Pretty squid post coitus planting a string of fertilized eggs on the sea floor.

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Photo of a large male escorting a female squid (Loligo vulgaris reynaudii) as she attaches an “egg finger” of about 100 eggs to an egg bed.

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Tentacle Sex

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Doesn’t everyone just love cephalopods? I find them to be a fascinating example of a body plan radically different from our own, the closest thing to a truly alien large metazoan on our planet. I try to keep my eyes open for new papers on cephalopod development, but unfortunately, they are rather difficult to study and data is sadly thin and tantalizing.

I just ran across a pair of papers by Jantzen and Havenhand (2003a, b) on squid mating. That’s close enough to development for me!

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Welcome, toad overlords

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In yet another example of evolution in action, investigators have documented morphological changes in the cane toads (Bufo marinus) that infest parts of Australia. They’re an invasive species that was introduced in a misbegotten attempt to control beetles that were damaging the sugar cane crop; as it turns out, they are aggressive predators that eat lots of other native fauna, and they secrete toxins that kill animals that try to eat them.

Another feature that contributes to their unwanted success is their rapid dispersal. Individuals can move up to 1.8km per night, occupying new territory at a distressing pace. In the 70 years since they were introduced, they’ve taken over a million square kilometers of Australia. Since dispersal into virgin territories is a significant advantage for the toads, it was predicted that there would be selection for faster migration rates in the population. The authors have several lines of evidence to show that this is the case.

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