The last time I hosted the Circus of the Spineless, I just did a series of photos—invertebrates are wonderfully photogenic. Here we go again, with another collection of gorgeous images of crunchy, squishy, slimy, tentacled, multi-legged, no-legged creatures.
A reader sent me a link to this myspace page (don’t quail in horror just yet!) called Bark, Hide and Horn—it’s by some folkies, and includes some songs. Love songs about mating molluscs and ants and various invertebrates! It’s very romantic. Listen if you’ve long had a lingering suspicion that you were born into the wrong phylum, or if just appreciate love no matter what the species involved are.
Consider it some theme music for the Circus of the Spineless, which will be appearing right here later today.
Halkieriids are Cambrian animals that looked like slugs in scale mail; often when they died their scales, called sclerites, dissociated and scattered, and their sclerites represent a significant component of the small shelly fauna of the early Cambrian. They typically had their front and back ends capped with shells that resembled those we see in bivalve brachiopods. Wiwaxiids were also sluglike, but sported very prominent, long sclerites, and lacked the anterior and posterior shells; their exact position in the evolutionary tree has bounced about quite a bit, but some argument has made that they belong in the annelid ancestry, and that their sclerites are homologous to the bristly setae of worms. One simplistic picture of their relationship to modern forms was that the halkieriids expanded their shells and shed their scales to become molluscs, while the wiwaxiids minimized their armor to emphasize flexibility and became more wormlike. (Note that that is a very crude summary; relationships of these Cambrian groups to modern clades are extremely contentious. There’s a more accurate description of the relationships below.)
Now a new fossil has been found, Orthozanclus reburrus that unites the two into a larger clade, the halwaxiids. Like the halkieriids, it has an anterior shell (but not a posterior one), and like the wiwaxiids, it has long spiky sclerites. In some ways, this simplifies the relationships; it unites some problematic organisms into a single branch on the tree. The question now becomes where that branch is located—whether the halwaxiids belong in a separate phylum that split off from the lophophorate family tree after the molluscs, or whether the halwaxiids are a sister group to the molluscs.
What’s happening in the Antarctic? Researchers are looking at seabed changes that result from global warming.
The researchers catalogued about 1,000 species in an area of the Antarctic seabed where warming temperatures are believed to have caused the collapse of overlying ice shelves, affecting the marine life below.
“This is virgin geography,” said expedition member Gauthier Chapelle. “If we don’t find out what this area is like now following the collapse of the ice shelf, and what species are there, we won’t have any basis to know in 20 years’ time what has changed and how global warming has altered the marine ecosystem.”
Here’s what’s cool: lots of photos of these creatures.
You all remember Violet, the jar-opening octopus, I’m sure—well, Violet is also quite the fierce predator. I would suggest that keeping a pet octopus is not a wise decision if you happen to be an arthropod.
Speaking of hugging your squid today, A colossal squid, Mesonychoteuthis hamiltoni, has been caught — it’s about 10 meters long and weighs about 450 kg. The place to go for all the information is TONMO, of course; I’ll just share some of the pretty pictures with you.
Cool: here’s a duck with four hindlimbs.
I have to gripe about the description, though:
A rare mutation has left eight-day-old Stumpy with two extra legs behind the two he moves around on. … The mutation is rare but cases have been recorded across the world.
No, no, no. This is almost certainly not the result of a mutation, and it’s one of my pet peeves when the media makes this wrong assumption, that every change in a newborn is the product of a genetic change. This is the result of a developmental error, not a genetic one, most likely caused by a fusion of two embryos in a single egg.
(via Apostropher)
