Eunice aphroditois (Bobbit Worm) Care Guide
Eunice aphroditois is a large predatory polychaete and a notorious live-rock hitchhiker that ambushes prey from a sediment burrow.
Compiled by Aquairi from published sources · Published · Updated
Overview
Eunice aphroditois, the bobbit worm, is a large marine polychaete of the family Eunicidae. It is a predatory bristle worm with an iridescent, deep purple to black body and five antennae on the head, and it can snap prey in half with retractable mandibles. In the aquarium hobby it is regarded as an unwanted pest that arrives unseen on live rock.
Taxonomy
- Family: Eunicidae
- Order: Eunicida
- Class: Polychaeta
- Scientific name: Eunice aphroditois
Habitat
The species lives mainly in the Atlantic Ocean and is also found in the Indo-Pacific. It inhabits coral reefs, sandy and muddy sediments, and areas around rocks and sponges, at depths recorded down to about 95 metres. It burrows into soft sediment, leaving only its sensory antennae exposed.
Size
- Length: from under 10 cm to nearly 3 m
- Maximum recorded length: 299 cm
- Body width: about 25.5 mm
- Lifespan: 3-10 years
Diet
It is an ambush predator. The worm buries its body in soft sediment and waits until its antennae detect prey, then strikes with its mandibles. It feeds as a carnivore on many fish species, can also act as an omnivore consuming algae, and functions as a decomposer of dead and decaying matter.
Compatibility
Eunice aphroditois is not reef-safe or fish-safe. In a closed system it will hunt fish and invertebrates, making it incompatible with all tankmates. If identified, it should be located and removed from the aquarium.
Bobbit Worm (Eunice aphroditois): Reproduction and Pest Notes
Overview
Eunice aphroditois is a large eunicid polychaete of the family Eunicidae. Recorded lengths span from under 10 cm to nearly 3 m, with the longest specimen measured at 299 cm, while the body remains only about 25 mm wide. It is an ambush predator that burrows in soft sediment and strikes passing prey with sharp mandibles. In aquaria it is regarded purely as a pest.
Spawning & Egg-brooding
Published biology indicates broadcast spawning rather than parental care. During spawning, individuals release sperm and eggs into the water column, where external fertilisation occurs. There is no den-building or egg-brooding stage, which separates this worm from cephalopods that tend their clutches.
Hatchling/Juvenile Care
Fertilised embryos develop into planktonic trochophore larvae that drift before settling and metamorphosing into juvenile worms. Because the species is treated as a pest, there is no established captive rearing protocol; small specimens most often enter tanks already as juveniles concealed in live rock.
Common Challenges
- Small individuals evade detection by hiding inside live rock when introduced to a tank.
- The worm hides in narrow burrows, making physical removal difficult.
- It depletes fish and invertebrate populations through ambush predation.
- It shows limited regeneration, primarily of posterior (tail) segments; claims of asexual reproduction by splitting are not scientifically supported.