Some two-bit publicity hound can die, and that’s all you can find on any of the television channels … a whole grand species can go extinct, and there’s almost nothing.
Say goodbye to the Yangtze River dolphin. It is officially extinct. The funeral will be poorly attended, and it will be forgotten, except in a few academic papers.
Since I was asked what a cnidarian “head” is in reference to this work on multi-headed cnidarians, I’ll answer. In short, they don’t have one.
It’s a collision! Two great carnivals on the same day. Check out Carnival of the Spineless #23 from sodden Great Britain, where the molluscs are thriving, and also read Tangled Bank #85, the Reductionist’s Tale at Migrations.
This is a short video clip of myotome formation in a zebrafish embryo — it’s the subject of an upcoming column in Seed, so I’m putting a short visual aid here.
You can Download the Quicktime movie (620K), or you can watch it via YouTube. Watch closely, it’s short and it flies by!
People are always arguing about whether primitive apes could have evolved into men, but that one seems obvious to me: of course they did! The resemblances are simply too close, so that questioning it always seems silly. One interesting and more difficult question is how oysters could be related to squid; one’s a flat, sessile blob with a hard shell, and the other is a jet-propelled active predator with eyes and tentacles. Any family resemblance is almost completely lost in their long and divergent evolutionary history (although I do notice some unity of flavor among the various molluscs, which makes me wonder if gustatory sampling hasn’t received its proper due as a biochemical assay in evaluating phylogeny.)
One way to puzzle out anatomical relationships and make phylogenetic inferences is to study the embryology of the animals. Early development is often fairly well conserved, and the various parts and organization are simpler; I would argue that what’s important in the evolution of complex organisms anyway is the process of multicellular assembly, and it’s the rules of construction that we have to determine to identify pathways of change. Now a recent paper by Shigeno et al. traces the development of Nautilus and works out how the body plan is established, and the evolutionary pattern becomes apparent.
A little knowledge would short circuit a lot of strange speculation. That picture to the right is of a shark caught in Malaysia, and people are calling those odd dangly bits “legs”. Despite the fact that someone said what they actually are in a comment early on, there are people arguing both that a shark with legs is evidence for evolution, and that it is evidence for creation.
They’re both wrong.
It’s a male shark. Those are the shark’s claspers, or intromittent organs. The shark does the usual act you’d expect with a female of the species, and like many shark species, it has clasper spurs, or little poky bits that help lock the organ into the female’s cloaca while he gets happy.
They aren’t homologous to legs at all. We also wouldn’t expect to find legs on a shark — they aren’t in the lineage that led to tetrapods.
I’m actually most surprised that a worker at the Malaysian Fisheries Development Board, who found this animal, didn’t recognize that these were just ordinary claspers. Anyone who has worked with sharks for even a little while would know about these structures. I suspect someone at the board is pulling the media’s, and the public’s, leg.
You know you want to see this: here’s a photo of two sharks getting affectionate. Shark lovin’ often involves a fair amount of biting and tearing, and leaves scars that you can find in captured specimens, so I don’t recommend trying this at home. Especially since sharks don’t believe in safewords.
A few years ago, everyone was in a tizzy over the discovery of Flores Man, curious hominin remains found on an Indonesian island that had a number of astonishing features: they were relatively recent, less than 20,000 years old; they were not modern humans, but of unsettled affinity, with some even arguing that they were like australopithecines; and just as weird, they were tiny, a people only about 3 feet tall with a cranial capacity comparable to a chimpanzee’s. This was sensational. Then on top of that, add more controversy with some people claiming that the investigators had it all wrong, and they were looking at pathological microcephalics from an isolated, inbred population, and then there were all kinds of territorial disputes and political showboating going on, with the specimens taken out of the hands of the discoverers, passed off to a distinguished elderly scientist whose lab damaged them, etc., etc., etc. It was a mess of a story, and the basic scientific issues are still unsettled.
Now the leader of the investigators who found the specimens has written a book, A New Human: The Startling Discovery and Strange Story of the “Hobbits” of Flores, Indonesia(amzn/b&n/abe/pwll), by Mike Morwood and Penny Van Oosterzee. I’m coming to this a bit late — Afarensis reviewed it already this spring — but finally got far enough down in my pile of books to encounter it.
Next time GrrlScientist comes to visit, we’re going to have to record what she says early in the morning, and then play it back ten times faster — I have a suspicion that we’ll hear birdsong.
At least, that’s the way this video art installation by Marcus Coates works. He had people sing strange little nonsense tunes (you can hear one here) that, when played back at a greater speed, recreated the songs of wild British birds. Why, if GrrlScientist had only talked a little faster, I’m sure the whole house would have sounded like an exotic tropical island inhabited by parrots!
