A worm that looks like a pig’s backside

Those crazy marine biologists! What wacky prank will they think up next? They’ve only gone and named a worm after a pig’s posterior.

Chaetopterus pugaporcinus. Image: Karen Osborn (c) 2006 MBARI

The Pigbutt worm, Chaetopterus pugaporcinus is a bizarre sort of marine worm – about the size and shape of a marble, it actually looks very much like a cartoon animal’s rear end. It’s not just good for a bit of toilet humour, but also an interesting taxonomic and evolutionary puzzle. Recent research at Monterey Bay Aquarium Research Institute on this floating orifice shows it’s actually related to the Chaetopterid worms, adults of which are sedentary worms, but this one floats freely. Larvae of such worms normally float about, but the adults settle down and live attached to the seabed. So maybe Chaetopterus pugaporcinus is in the process of making an evolutionary jump from one mode of life to another – a process very often achieved by retaining larval characteristics, and known as the phenomenon of neoteny. For example, our own hairless state, anomalous amongst primates, is thought to be a neotenous characteristic (an idea which inspired the title of the famous book The Naked Ape). So if you smirk at a bum-like worm, don’t forget that you may be no more than an undergrown ape yourself.

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