Sternaspid Worm

Image: Kelly Sendall, Sergio I. Salazar-Vallejo

Ah...

These would be one of the less worm-like worms!

Image: Kelly Sendall, Sergio I. Salazar-Vallejo

We've seen some extremely unwormly worms before, particularly those flat, round Myzostomids who plaster themselves onto the branches of crinoids. This time we're looking at an entirely different kind of other-wormliness: the short, rotund polychaetes of the Sternaspidae family.

Looks like some polychaetes really enjoy challenging the worm status quo!

Image: Kelly Sendall, Sergio I. Salazar-Vallejo

Sternaspids reach about 1 or 2 centimetres (under an inch) long and live buried head down in the surface layers of the sea floor. They can be found all over the world, from the intertidal zone all the way down to the deep abyss.

No-one knows how many species there are since scientists are still trying to work out which physical differences indicate a separate species and which are differences between individuals, subspecies or habitat. Some people have even suggested that there could be just one species all over the world!

Image: University of Bergen

One thing everyone can agree on is that Sternaspids usually look a bit like a toe. A ghastly, diseased toe. Probably from a gnome with gangrene or something.

But that's before the... face type thing comes out. Looks like gangrene is the least of that gnome's problems. He has haunted toes!

Image: Kelly Sendall, Sergio I. Salazar-Vallejo

Sternaspid worms can be divided into three parts. There's the abdomen, which is flabby and maggoty.

Then there's the introvert. It consists of the head and thorax and can be safely tucked into the abdomen when the Sternaspid wants the toe look. The head is covered in rows of spines, presumably for digging down into the sand and munching on whatever edible bits and bobs they come across.

Image: Kelly Sendall, Sergio I. Salazar-Vallejo

On the other end is the shield, or what I like to think of as the "ghastly, diseased toenail". It's spiky but also surprisingly pretty, like a tiny oyster shell or tree rings. In most Sternaspids it's tough and chitinous, though in a few it's soft and sticky enough to be constantly covered in sand. Either way, it's a bad way for a toenail to be. Cool door, though! It seems the shield may well serve to block the entrance of their burrow.

Oh, and don't forget the curly-wurlies! Behind the shield a veritable afro of curly tentacles can poke out of the burrow and collect oxygen while the rest of the worm remains underground.

Image: Sergio I. Salazar-Vallejo, Galina Buzhinskaja

So if you ever find tentacles and spikes growing out of your toes and your toenails start to look a bit like shellfish, please visit your doctor immediately. If it doesn't have a head, there's still time.