Lots of people have been sending me the link to the Vintage Octopus Pulp Covers site. It’s very cool.
It makes me wonder why so many people are infatuated with cephalopods, though. Weirdos.
Once upon a time, there was teeny-weeny adorable little fish called Paedocypris. Then, one day, a population of bulldozers invaded their habitat, and they couldn’t compete, and they died.
The good news, though, is that a new species of Paedocypris has been discovered.
Amirrudin said the new discovery was significant because it was the only undisturbed habitat of this species. “There are still thousands of the fish in that peat swamp. My worry is that this habitat will end up like the one in Bukit Merah, disturbed by the construction of a road that killed all the specimens,” he said.
Maybe we need to classify bulldozers as an invasive species, one that can be dismantled on sight.
(via Marcus)
I never heard of this before: there exists a rare, giant, albino earthworm in the scrub prairies of the Palouse. It grows to be 3 feet long, and smells like lilies.
I scarcely believed it myself—that’s also Sasquatch country out there, you know—so I had to look it up. The Giant Palouse Earthworm (Driloleirus americanus) is real. They’re so rare, though, that one hasn’t been spotted in almost 20 years…until last year. A new specimen was found, and unfortunately, fixed in formaldehyde right away. I thought this quote was a little sad.
Unlike the celebration touched off by last year’s sighting in Arkansas of the ivory-billed woodpecker—a bird not seen in 60 years and thought to be extinct—the giant earthworm Sanchez-de Leon found last year already has been consigned to a jar of formaldehyde.
“Realistically, the giant Palouse earthworm is a lot less charismatic than a giant woodpecker,” said James “Ding” Johnson, head of the University of Idaho’s Department of Plant, Soil and Entomology Sciences.
My apologies to GrrlScientist, but I’d much rather see a giant white worm than some boring old bird.
One of the most evocative creatures of the Cambrian is Anomalocaris, an arthropod with a pair of prominent, articulated appendages at the front of its head. Those things are called great appendages, and they were thought to be unique to certain groups of arthropods that are now extinct. A while back, I reported on a study of pycnogonids, the sea spiders, that appeared to show that that might not be the case: on the basis of neural organization and innervation, that study showed that the way pycnogonid chelifores (a pair of large, fang-like structures at the front of the head) were innervated suggested that they were homologous to great appendages. I thought that was pretty darned cool; a relic of a grand Cambrian clade was swimming around in our modern oceans.
However, a new report by Jager et al. suggests that that interpretation may be flawed, and that sea spider chelifores are actually homologous to the chelicerae of spiders.
I’m going to introduce you to either a fascinating question or a throbbing headache in evolution, depending on how interested you are in peculiar details of arthropod anatomy (Mrs Tilton may have just perked up, but the rest of you may resume napping). The issue is tagmosis.
Read and discuss:
Or talk about anything you want. The pope’s presence annihilates ice cream and tampons. Bill Frist really needs to take a shower before working in the Senate. What kind of penalties would be appropriate for Kenny Boy? I’m sure you can all think of something to talk about—I’m buckling down for a few hours to finish reviewing a paper.
I just learned (via John Lynch) about a paper on cetacean limbs that combines developmental biology and paleontology, and makes a lovely argument about the mechanisms behind the evolution of whale morphology. It is an analysis of the molecular determinants of limb formation in modern dolphins, coupled to a comparison of fossil whale limbs, and a reasonable inference about the pattern of change that was responsible for their evolution.
One important point I’d like to make is that even though what we see in the morphology is a pattern of loss—whale hindlimbs show a historical progression over tens of millions of years of steady loss, followed by a near-complete disappearance—the molecular story is very different. The main players in limb formation, the genes Sonic hedgehog (Shh), the Fgfs, and the transcription factor Hand2, are all still present and fully functional in these animals. What has happened, though, is that there have been novel changes to their regulation. Even loss of structures is a consequence of changes and additions to regulatory pathways.
I’m going to briefly summarize an interesting new article on cnidarian Hox genes…unfortunately, it requires a bit of background to put it in context, so bear with me for a moment.
First you need to understand what Hox genes are. They are transcription factors that use a particular DNA binding motif (called a homeobox), and they are found in clusters and expressed colinearly. What that means is that you find the Hox genes that are essential for specifying positional information along the length of the body in a group on a chromosome, and they are organized in order on the chromosome in the same order that they are turned on from front to back along the body axis. Hox genes are not the only genes that are important in this process, of course; animals also use another class of regulatory genes, the Wnt genes, to regulate development, for instance.
A gene can only be called a Hox gene sensu stricto if it has a homeobox sequence, is homologous to other known Hox genes, and is organized in a colinear cluster. If such a gene is not in a cluster, it is demoted and called simply a Hox-like gene.
Hox genes originated early in animal evolution. Genes containing a homeobox are older still, and are found in plants and animals, but the particular genes of the Hox system are unique to multicellular animals, and that key organization arrangement of the set of Hox genes in a cluster is more unique still. The question is exactly when the clusters arose, shortly after or sometime before the diversification of animals.
If you take a look at animal phylogeny, an important group are the diploblastic phyla, the cnidarians and ctenophores. They branched off early from the metazoan lineage, and they possess some sophisticated patterns of differentiation along the body axis. We know they have homeobox containing genes that are related to the ones used in patterning the bodies of us vertebrates, but are they organized in the same way? Did the cnidaria have Hox clusters, suggesting that the clustered Hox genes were a very early event in evolution, or do they lack them and therefore evolved an independent set of mechanisms for specifying positional information along the body axis?
Rabbits are the most freaky of all mammals (right, Chris?) They’re thriving, though—they’re all over my lawn, and if this summer is anything like last year, I’ll have to go out about once a week and scrape one off the road running by my house.
I did not know that interesting fact about their scrotum, though.
