It’s up: a taxonomically organized and prettily illustrated collection of posts about invertebrates. You know you must go read it.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
It’s up: a taxonomically organized and prettily illustrated collection of posts about invertebrates. You know you must go read it.
Bone is a sophisticated substance, much more than just a rock-like mineral in an interesting shape. It’s a living tissue, invested with cells dedicated to continually remodeling the mineral matrix. That matrix is also an intricate material, threaded with fibers of a protein, type II collagen, that give it a much greater toughness—it’s like fiberglass, a relatively brittle substance given resilience and strength with tough threads woven within it. Bone is also significantly linked to cartilage, both in development and evolution, with earlier forms having a cartilaginous skeleton that is replaced by bone. In us vertebrates, cartilage also contains threads of collagen running through it.
These three elements—collagen, cartilage, and bone—present an interesting evolutionary puzzle. Collagen is common to the matrices of both vertebrate cartilage and bone, yet the most primitive fishes, the jawless lampreys and hagfish, have been reported to lack that particular form of collagen, suggesting that the collagen fibers are a derived innovation in chordate history. New work, though, has shown that there’s a mistaken assumption in there: lampreys do have type II collagen! This discovery clarifies our understanding of the evolution of the chordate skeleton.
Say hello to Castorocauda lutrasimilis, a primitive mammalioform from the middle Jurassic—164 million years ago. Despite its great age, it has evidence of fur and guard hairs still preserved in the fossil, and was rather large for its time. It’s estimated to have weighed about 500g (about a pound) and was over 400mm (over a foot) long in life, and as you can see from the reconstruction, shows signs of being aquatic. In size and lifestyle, it probably resembled the modern platypus.
The inaugural edition of the Carnival of the Animalcules is up. It’s almost lunchtime, though, and you might want to wait until after you’ve eaten…especially before reading the one about fast-food toilet water.
Ah, the life of the female giant Australian cuttlefish…males fight for her affections, and during the mating season she will have sex with 2-8 different males each day, with an average total of 17 copulations per day. She can be picky, too, and rejects most of the mating attempts (yet still manages to mate up to 40 times a day). It must be a good life.
Males have a rougher time of it, I would think. There are many more males than females, and so it’s a struggle to get access to one; the bigger, stronger males will guard females, acting as a consort, and use aggressive displays to chase off competitors. What to do if you’re a smaller, but clever male?
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.
Olduvai George shows how to illustrate evolution , with pictures of Eusthenopteron, Pachyaena, and a thylacine.
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…
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.
