Organisms
pharyngula | April 12, 2006John Lynch beat me to this story about catfish feeding on land, so I'll be brief. It shows how the eel catfish, Channallabes apus, can manage to take an aquatic feeding structure and use it to capture terrestrial meals. Many fish rely on suction feeding: gape the mouth widely and drop the pharyngeal floor, and the resulting increase in volume of the oral cavity just sucks in whatever is in front of the animal. That doesn't work well at all in the air, of course—try putting your face a few inches in front of a hamburger, inhale abruptly, and see how close you come to sucking in your meal. So…
pharyngula | April 7, 2006Opisthoteuthis depressa
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | April 5, 2006My wife thought this story about left-handed snails having a competitive advantage, in that they seem to be better able to escape predation by right-handed crabs, was pretty cool. She also recalled that I'd scribbled up something about snail handedness before, so to jump on the bandwagon, I've brought those stories over from the old site.
The handedness of snail shells is a consequence of early spiral cleavages in the blastula. It's a classic old story in developmental biology—everyone ought to know it!
There was also a story last year about shell chirality in Euhadra. There, it wasn't a…
pharyngula | April 5, 2006
Since Coturnix turned me on to this paper on snail chirality in PLoS (pdf), I had to sit down and learn something new this afternoon.
Chirality is a fascinating aspect of bilaterian morphology. We have characteristic asymmetries—differences between the left and right sides of our bodies—that are prescribed by genetic factors. Snails are particularly interesting examples because snail shells have an obvious handedness, with either a left-(sinistral) or right-handed (dextral) twist, and that handedness derives from the arrangement of cell divisions very early in development.
Sinistral (left)…
pharyngula | April 5, 2006
Developmental biologists are acutely interested in asymmetries in development: they are visible cues to some underlying regional differences. For instance, we'd like to know the molecules and interactions involved in taking a seemingly featureless sphere, the egg, and specifying one side to go on to form a head, and the the opposite side to form a tail. We'd like to understand why our back (or dorsal) side looks different from our belly (or ventral) side. One particularly intriguing distinction, though, is the left-right axis. For the most part, left and right are nearly identical, mirror-…
pharyngula | April 5, 2006Paleontologists have uncovered yet another specimen in the lineage leading to modern tetrapods, creating more gaps that will need to be filled. It's a Sisyphean job, working as an evolutionist.
This creature is called Tiktaalik roseae, and it was discovered in a project that was specifically launched to find a predicted intermediate form between a distinctly fish-like organism, Panderichthys, and the distinctly tetrapod-like organisms, Acanthostega and Ichthyostega. From the review article by Ahlberg and Clack, we get this summary of Tiktaalik's importance:
First, it demonstrates the…
pharyngula | March 31, 2006Octopus vulgaris
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | March 30, 2006
The New England Journal of Medicine sometimes provides great stuff to read over breakfast, like this story of a man who returned from a trip to Hungary with his guts infested with worms, Enterobius vermicularis. OK, so it's not much of a story…but the cool thing is that they provide a movie clip of his colonoscopy, and you can watch the worms writhe.
(via Over My Med Body)
pharyngula | March 28, 2006Besides being my boyhood home and the place where most of my relatives live, they're finding dead Humboldt squid washing ashore in Puget Sound. Paradise!
Dan Penttila has been walking Washington's beaches for more than 50 years, made a career of studying small fish born there, and knows pretty much what to expect.
But he could hardly believe it when one day in January, he stumbled over a squid, a species normally found in the warm waters off Mexico and Southern California: the Humboldt squid.
pharyngula | March 27, 2006
Oh, my. It's a movie of Scolopendra killing and eating a mouse. It's not for the faint of heart: first there's the squeaking, the terrible squeaking, and then there's the chewing, and it goes on and on and on and on…
There is no god.
Or, as is noted in the comments, god is a righteously evil being.
(via Apostropher)
pharyngula | March 24, 2006Metasepia pfefferi, Pfeffer's Flamboyant Cuttlefish
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | March 22, 2006
Check out this pre-pterosaur, Sharovipteryx: delta-winged, with a canard.
pharyngula | March 18, 2006
We haven't had enough fossil penguins here, so let me rectify that deficiency. Below the fold you'll find a reconstruction of Waimanu, a 61-62 million year old penguin that was discovered in New Zealand.
Oh, and Carl Zimmer has posted a photo of the bird with its skin and feathers on.
Reconstruction of Waimanu (composite of W. manneringi and W. tuatahi, based on original art
by Chris Gaskin ©Geology Museum, University of Otago). ca, caudal vertebrae; ce, cervical
vertebrae; cm, carpometacarpus; cr, coracoid; fb, fibula; fe, femur; fu, furcula; hu, humerus; sk,
skull, md, mandible; oc, os…
pharyngula | March 17, 2006Sepioteuthis sepiodea
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | March 16, 2006Check out these compendia of blogginess and comment on them, or anything else that strikes your fancy.
Skeptics' Circle
I and the Bird
Carnival of the Liberals
pharyngula | March 16, 2006Nah, I thought this has got to be a joke:
The Pentagon's defence scientists want to create an army of cyber-insects that can be remotely controlled to check out explosives and send transmissions.
But no…there is actually a DARPA call for proposals.
DARPA seeks innovative proposals to develop technology to create insect-cyborgs, possibly enabled by intimately integrating microsystems within insects, during their early stages of metamorphoses. The healing processes from one metamorphic stage to the next stage are expected to yield more reliable bio-electromechanical interface to insects, as…
pharyngula | March 15, 2006
Juravenator starki is a new small theropod dinosaur from the late Jurassic—the specimen is exceptionally well-preserved, and retains fossilized imprints of its skin. The surprising thing about it is that its anatomy puts it smack in the middle of a large clade of coelurosaurs, members of which are known to have feathers…and its skin is bare and scaly. What it suggests is that feather evolution was complicated (no surprise there, actually), and that some lineages secondarily lost their feathery covering, or that there were seasonal or age-related or regional variations in feather expression.…
pharyngula | March 10, 2006I've seen a few births, and they're messy, bloody, and tiring…but you know, it could be much worse.
pharyngula | March 10, 2006The Schoepenhauer awards are a delectable collection of interesting descriptions of parasites, such as the roundworm.
Today we'll introduce you to the Intestinal Roundworm, a hideous parasite which infects one out of every four people in the world. That's not a misprint: one out of four. More than one and a half BILLION people. Yup, every fourth person on this planet is nothing but a travelling worm farm.
Sweeeeet, right?
But hey, do you remember that moment in a certain cult movie when Sean Connery, dressed in little more than bandoliers and a speedo, is rummaging through a library and…