gerbilbox

I probably spend more time watching my medusa worms scour the sand for food than I spend looking at my clownfish. I would watch my bristle worms too but they rarely make public appearances. Tonight, I found these guys swimming towards my moonlight:



It's about 6-7mm long, and I'm pretty certain that it's an epitoke, a free-swimming reproductive stage of an annelid worm (bristle worms, medusa worms, spaghetti worms, featherduster worms, etc). Some worms reproduce by detaching the hind section of their body, called an epitoke. The epitoke grows out their bristles to act as swimming paddles, swarm to the surface with other fellow epitokes and then release their sperm and egg in a terminal orgy. This happens while the original worm stays safely where it is. If you ever heard of southern Polynesians eating palola worms, that's right, they are eating epitokes.

This is the second time that I've seen epitokes in my tank, so I'm happy that they're doing well enough to breed. I have medusa, bristle, mini featherduster, and spionid worms in my tank, and I'm not sure which ones are breeding tonight since not all annelid families form epitokes.

If you ever see free-swimming worm-like critters your tank one night, you now know what they are.

The picture above isn't great, I don't have a true macro lens and this is the best show that I got. Maybe that should be my next aquarium investment, a true macro lens