Organisms
pharyngula | October 4, 2006The Science Pundit has a collection of graphics and movies illustrating echinoderm locomotion. Tube feet are spiffy.
pharyngula | September 30, 2006Here's a prediction for you: the image below is going to appear in a lot of textbooks in the near future.
(click for larger image)Confocal image of septuple in situ hybridization exhibiting the spatial expression of Hox gene transcripts in a developing Drosophila embryo. Stage 11 germband extended embryo (anterior to the left) is stained for labial (lab), Deformed (Dfd), Sex combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx), abdominal-A (abd-A), Abdominal-B (Abd-B). Their orthologous relationships to vertebrate Hox homology groups are indicated below each gene.
That's a technical…
pharyngula | September 29, 2006The work of Craig McClain (of Deep-Sea News) is written up in Science Daily—it's cool stuff. Also notable is that it is illustrated with a photo of a giant isopod…one of those creatures Kent Hovind calls a trilobite, and uses to support his contention that the earth is only 6000 years old (Look! Trilobites still live in the Arctic! Idjit.)
pharyngula | September 29, 2006Planktonic octopus larva
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | September 28, 2006Ah, the evils of strong drink. Or weak drink. You all know that you shouldn't drink alcohol to excess during pregnancy, and the reason is that it can affect fetal development. We take zebrafish eggs and put them on a real bender: we soak them in various concentrations of alcohol (which are hard to compare with human blood alcohol levels, I'm afraid, but trust me: these are such gross levels of ethanol that mere humans would be dead and pickled. Fish are tough), and let them stew for hours. Since fish development is much, much faster than human development, it's rather like having a woman…
pharyngula | September 28, 2006By popular request, here's a roughly annotated version of that zebrafish development movie.
Stuff to watch for:
This movie starts at the 8-16 cell stage. The cells of the embryo proper (blastomeres) are at the top, sitting on a large yolk cell.
The pulsing is caused by the synchronous early divisions of all the cells. They lose synchrony at the mid-blastula transition.
Epiboly is the process by which the cells migrate downward over the yolk. An arrow will briefly flash, pointing to about 11:00, in the direction of the animal pole (where the future nose will form, sorta). That happens…
pharyngula | September 28, 2006At my talk on Tuesday, the centerpiece was a short movie of zebrafish development—I was trying to show just how amazingly cool the process was. People seemed to like that part of the show, at least, so I thought I'd try to figure out this YouTube doohickey and upload it for general viewing. So here it is, a timelapse recording of about 18 hours of zebrafish embryology compressed into 48 seconds:
I've got more, and my students will be making videos of their own soon enough, so maybe I'll try uploading some other stuff soon. I'm discovering that YouTube is a little tricky about the aspect…
pharyngula | September 26, 2006
It’s April (not anymore—it's September as I repost this), it’s Minnesota, and it’s snowing here (not yet, but soon enough). On days like this (who am I fooling? Every day!), my thoughts turn to spicy, garlicky delicacies and warm, sunny days on a lovely tropical reef—it’s a squiddy day, in other words, and I’ve got a double-dose of squidblogging on this Friday afternoon, with one article on the vampire squid, Vampyroteuthis infernalis, and this one, on squid evolution and cephalopod Hox genes.
Hox genes are members of a family of genes with a number of common attributes:
They all contain a…
pharyngula | September 26, 2006Archy goes looking for mastodons, finds fanged hippos with massive organs instead.
pharyngula | September 26, 2006
We need to appreciate beer more. Alcohol has a long history in human affairs, and has been important in purifying and preserving food and drink, and in making our parties livelier. We owe it all to a tiny little microorganism, Saccharomyces cerevisiae, which converts complex plant sugars into smaller, simpler, more socially potent molecules of ethanol. This is a remarkable process that seems to be entirely to our benefit (it has even been argued that beer is proof of the existence of God*), but recent research has shown that the little buggers do it all entirely for their own selfish reasons…
pharyngula | September 25, 2006Awww. Take a look at the nice photography of adorable little frog embryos. The rest of the site also has some lovely photos of Australian fauna…I'd like to know what kind of camera/lens was used for those close-ups of frog embryos.
pharyngula | September 24, 2006Since Friday's cephalopod was a repeat (sorry, it's such a lovely picture that it caught my eye again), here's another to compensate.
Sepia pharaonis
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | September 22, 2006Sepia pharaonis, male on the left, female on the right
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | September 21, 2006Don't be too grossed out, but the University of Wisconsin Madison has put a whole series of high-quality videos of human dissection online. It's extremely cool, but not for the squeamish—there's more than just the sight of a cadaver getting hacked up, and the sound of a saw on bone or a chisel being used to peel up the cranium are, ummm, memorable. At least you're spared the odor and the textures.
I'd almost forgotten how muscular gross anatomy is—it takes some heft and brute force to take apart a body.
(via Mind Hacks)
pharyngula | September 21, 2006First I reported that Palaeos was lost, and then that it might be found, but now it looks like we can safely say it is being reborn. The old version of Palaeos has been at least partially restored, but the really important news is that a Palaeos wiki has been set up and people are working on reassembling old content and creating new information in a much more flexible format. If you've got some phylogenetic or palaeontological expertise, you might want to consider joining the Palaeos team and helping out with this big project.
pharyngula | September 20, 2006Say hello to Selam, or DIK-1-1, a new and very well preserved member of the family discovered in Dikika, Ethiopia. She belongs to the species Australopithicus afarensis and is being called Lucy's little sister.
She was only a toddler when she died about 3.3 million years ago, and from the teeth the authors estimate that she was about 3 years old. Most of the skeleton is intact, but doesn't seem to have yet been fully extracted from the matrix.
Some of the surprises: the hyoid bone is chimpanzee-like, and implies chimp-like vocalization abilities. She had a long way to go before she could…
pharyngula | September 16, 2006An old pal of mine, the splendiferously morphogenetical Don Kane, has brought to my attention a curious juxtaposition. It's two articles from the old, old days, both published in Nature in 1981, both relevant to my current interests, but each reflecting different outcomes. One is on zebrafish, the other on creationism.
1981 was a breakthrough year for zebrafish; I think it's safe to say that if one paper put them on the map, it was Streisinger et al.'s "Production of clones of homozygous diploid zebra fish (Brachydanio rerio)"1. George Streisinger was the father of zebrafish as a model system…
pharyngula | September 16, 2006For a rather different kind of squid, here's a pretty image. There's also a mammal in the picture, which I understand some people might find not quite safe for work, so don't click through unless you can handle viewing an exposed superficial epithelium.
pharyngula | September 16, 2006
Whoa…watch this phenomenal video of the Vampire Squid. They've caught it feeding and using a few sneaky tricks to escape predators.
pharyngula | September 15, 2006
Via El PaleoFreak (in Spanish; here's a translation), I find this strange little cockatoo chick, and even better, take a look at these wonderful simulations of feather development.