Remember how I said Angus was insisting
octopus were arachnids last week, and wouldn't believe me when I told him they were mollusks?
We watched a program on the Science Channel last night called
Origins: The Battle for the Planet, which dealt with evolution, and the
fossils of the Burgess Shale. At that time, a tiny flat swimming critter named
Pikia, first noted chordate and possible ancestor of all vertebrates, may have had a rough time escaping predators such as
Anomalocarus, a voracious arthropod forerunner, which may have been up to six feet long, or the nautiloids, the large ammonite forerunners. There was a lot of interesting CGI animation of the creatures of what is now the Burgess Shale set of fossils, interspersed with interviews with the scientists and, during longer period of narration, footage of a hairless athlete in a Speedo stepping around and over a bunch of snails and cockroaches, symbolizing, I guess, the competition between arthropods, mollusks, and vertebrate precursors.
(I have to admit during these sections of the show I sort of lost track of the narration - he was quite interesting to look at. John said he had been the volleyball team during the Seville Olympics, and has a condition that keeps him from growing any hair anywhere on his body - not even eyelashes or eyebrows.)
The animation of living versions of the fossils was pretty interesting, as I've always wanted to see what these critters looked like when they were alive - they even showed my favorite,
Hallucigenia, although only for a few seconds. When I first learned about these fossils in college from my then-boyfriend, a Geology major, it was thought that we weren't even sure what phylum these animals belonged to. The one book I read on the subject (the late
Stephen Jay Gould's Wonderful Life) seemed to confirm that. However, some comments in this show led me to find out the Gould was not the last word on the subject, and
other authors feel that these critters are actually related to, or are ancestors of, animals existing today (I guess I need to do some more reading).
Hallucigenia seems to be related to
Peripatus, itself called a living fossil - something I at first found disappointing. Somehow it piqued my sense of the weird and non-conformist that all these animals seemed to be defying conventional classification. However, now it seems right - at least the
velvet worms (ha, a common name I was unaware of) are a rather weird phylum themselves.
However, the main point of this series, that vertebrates are somehow more successful, because their internal skeletons allowed them to form larger bodies, and therefore "better" colonize the land, bugged me. Possibly because we humans are considered to be the dominant species on the planet. There are other measures of success, aren't there? Insects may not have large bodies, but they are far more diverse than vertebrates. I guess if you count how much humans are affecting the ecosystem of the entire planet for the worse, we are the "winners."
Where was I going with this? Oh yes, getting back to my original starting point - since this show placed such an emphasis on "Mega-Mollusks," Angus now buys that octopuses are related to snails, and not spiders. If it's on tv, it must be true - whereas, mom isn't always to be believed.
*Sigh*
Twas ever thus.
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