Polychaetes · Eunicida · Eunicidae

Wonder-worm

Eunice aphroditois

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

The Bobbit worm, also spelt Bobbitt, or giant reef worm, is a polychaete annelid of the family Eunicidae. It lives on the floor of the Atlantic and the Indo-Pacific, where it buries its body in a bed of sand, gravel, mud or coral, waits patiently for a stimulus on one of its five antennae and strikes when it detects prey. Ranging in size from less than 10 centimetres to some 3 metres long, it is armed with sharp teeth and can strike at such speed that it cuts its prey in two. Although the worm hunts, it is omnivorous.

Size

1 m – 3 m

Diet

Carnivore

Feeds mainly on other animals.

Activity

Nocturnal

Active mainly at night.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

OceanCarnivore Nocturnal Solitary Ocean Worm

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Fun facts

Its strike is so fast and so powerful that it can cut a prey animal in two, and its common name comes from that reputation rather than from any biological trait.
Fossil burrows attributed to similar ambush worms have been found in Miocene rocks in Taiwan, with the same funnel structure that living ones leave behind.
In marine aquariums it sometimes turns up with no one knowing how, arriving as a stowaway in live rock, and is discovered when fish start disappearing at night.
It is a polychaete worm that can exceed three metres in length, and it lives buried in a burrow from which only its head protrudes.
It hunts from ambush with five sensory antennae spread over the sand. When something brushes them, it strikes with extraordinary speed and chitinous jaws capable of cutting a fish in two.
It became famous through a real-life case: in 2009, staff at the Newquay aquarium in Cornwall had long been baffled because fish kept disappearing and corals were turning up mutilated. When they dismantled the tank they found a specimen over a metre long that had arrived years earlier hidden in a piece of live rock.
Its chaetae, the lateral bristles, have an iridescent sheen that makes it unmistakable.
Its reproductive biology and longevity are poorly known, because it is almost impossible to observe in its natural environment.
The group's taxonomy is under revision: what is called Eunice aphroditois may correspond to several distinct species.

Life cycle & biology

Skeleton type: Invertebrate - no rigid skeleton (annelid)
Habitat & environment: Sandy, muddy and gravelly bottoms of warm waters, from 10 to 40 m

Sources consulted: https://es.wikipedia.org/wiki/Eunice_aphroditois