Tuesday, May 18, 2010
Creature Feature: Planarians
Some people may twitch at the sight of nightcrawlers, but planaria are a whole
different can of worms. These guys are just adorable! Most biology classes cover the various freshwater planarian species at some point; there are also a few land-based planaria. They are not as enchanting as yesterday's damselfly, but are still unbelievable in their own right.
For starters, they look adorably cartoonish. Even though they eat via a tube on their stomachs, they swim like little otters, and have some of the most ridiculous-looking (and primitive) eyespots in the animal world. They do not have focused, complex vision like we do; being cross-eyed is not a problem for these little guys. Their 'eyes' are just photosensitive.
They even "smile!" How cute is that? :3
Of course, planarians are not popular biology lab rats because of how goshdarn cute they are. Besides being one of the first critters to sport cephalization ('head-ness') and bilateral symmetry, they have insane regeneration capabilities.
As this extremely fucked-up Japanese cartoon (based off of an equally-FUBAR cartoon with a pink rabbit) demonstrates, cutting a planarian up will cause a whole new individual to be born. Yes, planaria lead the life of Rin from Mnemosyne; people cut them up like genuine sadists only to have them regenerate. This ability also leads to multi-headed planaria like these:
You know that debate about stem cells? These guys are like stem cell mania. The whole deal with stem cells is that they can become any part of an organism. One cut of these guys creates an entirely new worm. Holy fuck. Take that, vertebrates!
Of course, this regeneration is nothing compared to the immortal jellyfish...but that's a post for another day. ^_~