Land Planarian

Image: Wikimedia

When I first saw the words "Land Planarian" I thought it was some kind of tiny, desktop greenhouse. I imagined tiny gardens and tiny jungles, tiny fruit on tiny trees and tiny leaves adrift on tiny rivers. I imagined a miniature wonderland of lush foliage right there on the living room table.

But then I saw one.

Land Planarians are terrestrial flatworms. They look pretty darn nasty, all sludge and slime. Someone must have gone round asking people what they hate most about slugs and earthworms and then just threw the results together in an effort to make the world's most despised animal. I'm sure an evil scientist is cackling malevolently somewhere as we speak.

Image Blackbone Music via Flickr

This may explain why so little is known about Land Planarians. They seem to be remarkably understudied, seldom spoken of and it appears that many have never heard of them at all. It's nature's dirty little secret. In fact, were anyone's dirty little secret given life and left to fend for itself, I think it'd look just like a Land Planarian.

Being flatworms, Land Planarians have no circulatory or digestive organs. Everything is done through diffusion, such that they have to be flat and simple in shape to ensure all their cells get everything they need. Land Planarians don't even have a way of keeping water in, so they can only live in moist environments to avoid drying out. For these reasons most flatworms are tiny, but the most ambitious Land Planarians can reach 60 cm (2 feet) in length!

Despite this incredible fragility and squirmy, worminess, Land Planarians are actually predators. Some eat soft things like slugs, worms (jealous of their dashing good looks, no doubt) as well as other Land Planarians. Others manage tougher prey, insects and the like. No plates or cutlery is involved and most lamentable of all, neither is a napkin.

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A Land Planarian's best friend is a ghastly assortment of mucus. They follow mucus snail trails to sniff out prey, there's mucus to help them span wide gaps like Spiderman gone wrong, and then there's sticky mucus to entrap prey. Next comes the eversible pharynx, basically a throat that is turned inside-out and comes out of the mouth. This can be used to grab onto soft bodied prey, or cut into the exoskeleton of tougher fare. Glands then secrete digestive mucus to dissolve victims and create a meaty broth.

A small flatworm will have guts that are not much more than a sack. Larger ones will have a branching affair, all to ensure that every cell can absorb the nourishment as it washes by. Many don't even bother with an anus, they'll just pass waste out through the mouth. Others have one or several anuses. It seems to me that a 2 foot long flatworm probably wouldn't want to usher waste products all the way from the back to the front. Then again, I don't frequently ponder flatworm evacuation points.

It's horrible from beginning to end, but that's flatworms for you. I can't help but have a sneaking respect for something that looks so incredibly horrible, yet manages to get even worse when you learn more about it. Well done!

Image: Wikipedia

Gesundheit!

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Circus of the Spineless #70