I think it’s only fair I start this post with a disclaimer. If you are planning to go into the ocean at some point in the future you might want to skip this as once you read about the bobbit worm, it might put you off.
Not much is known about it, which might strike you as odd since it is one of the largest polychaete worms (it can grow up to 3 m long) and can slice a fish in half with the speed and power of its bite. The bobbit worm belongs to the genus Eunice which has a lot of problems with classification as ‘bobbit worm’ has been liberally applied to many identifications. This has led to the genus consisting of over 350 species. Because of this the worms have a wide distribution, they are said to be found in temperate and tropical waters at around 10-40 m deep, buried in the substrate or hidden in rocks and coral.
Despite their many taxonomical problems, what is commonly thought of as a bobbit worm should still be enjoyed for just how cool/horrifying they are, as you can see from this video.
I hope you’re still with me and haven’t decided that’s enough internets for one day! The ‘mouth’ is actually an adapted part of the bobbit worm’s pharynx, which it turns inside out when catching prey. The nasty looking pincers are made with a pair of mandibles and four-six pairs of maxillae and this combines with the antennae which are used to sense its prey. There is a pair of eyes at the base of the antennae but it is unclear if they are used for sensing prey. Normally ambush predators, the bobbit worm will scavenge for food when hungry and they are omnivorous.
Check out marine biologist Christopher Mah’s excellent echinoblog for more detail in the trouble with defining the Eunice genus and how it really came to be known as the bobbit worm.