BioEssays regularly runs a feature called "My Favorite Animal"; this month's choice is barely an animal at all, the placophoran Trichoplax adhaerens. I've written about Trichoplax before. It's a strange creature, a small flat blob that creeps amoeba-like over the substrate, that replicates by simply splitting in two, and that seems to have no distinguishing features at all—no head, no sense organs, no nervous system, no gut, just a collection of cells that hang together and slurp up algal slime. They are, however, multicellular, and their bodies contain at least four functionally distinct cell types, and the molecular evidence suggests affinities to other animal groups (they have a ProtoHox/ParaHox gene, for instance)…so they are definitely metazoans. They are just the simplest, barest kind of metazoan we can find now.
Continue reading Mysterious Trichoplax (on Pharyngula)
3 Comments
Pete Dunkelberg · 27 November 2005
A fine animal indeed. I'll have to see if I can find some of them. There is more about their natural history online here and there are some capture methods here.
bill · 27 November 2005
A fine scraping from the Primordial Soup if I ever saw one!
In fact, it bears more than a passing resemblance to Connie Morris on the Kansas State School Board. Especially the part about slurping up algal slime. That's our Connie!
Jack Krebs · 28 November 2005
I know that straight science posts like this don't get a lot of comments sometimes, but I (and I hope many others) read and enjoy them. I thought this was fascinating - looking at creatures at the figurative dawn of differentiation.