biology articles

Ribbon worm hunting for the first time

Every master has humble beginnings.

Ribbon worms (or nemerteans) are predators. They use a proboscis full of toxins, sometimes with sharp stilets or creepy branching patterns, to paralyze their prey and swallow them whole.

Lineus viridis feeding. Video by Eduardo Zattara.

The eversion of the proboscis occurs by an interesting mechanism. It’s based on muscular power and pressure in the cavity where the proboscis is kept, known as the rhynchocoel. A quick eversion of the proboscis hits the prey which, unaware of the danger, becomes unable to move.

The entire thing is more impressive considering that nemerteans have no visual system, only light-detecting photoreceptors. They do have, however, powerful sensory slits and cerebral organs on their head.

We study nemerteans in the laboratory by culturing them from eggs to adult worms. We managed to capture in film the first time that these worms got to use their proboscis to hunt for the first time.

The prey in this case was not another creeping animal, but some rather ludicrous eggs of an annelid worm. A great way to practice hunting skills for these little fellas.

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