The strike is powered by a muscular eversible pharynx carrying hardened jaw pieces. Contact with the antennae triggers it, and the worm hauls prey down into the sediment where escape is impossible. Divers report seeing a fish disappear with no visible predator, which is what gives the animal its reputation.
Size claims need care. Individuals are commonly reported around one metre, with larger figures circulating from photographs and aquarium finds. A well-known specimen removed from a British public aquarium tank in 2009 was widely reported at over a metre. Uncontrolled measurements of an elastic-bodied worm invite the same stretching problem as other long worms.
Two further points are commonly muddled. The popular name dates only to the 1990s and has no bearing on the animal's biology, including a persistent and unsupported story about the female eating the male. And the taxonomy is unstable: specimens photographed worldwide and labelled Eunice aphroditois probably represent several species, so range and size figures aggregate more than one animal.