Medusa worm

Appearance

The medusa or spaghetti worm has a segmented body that is rarely visible because it lives inside a soft tube lodged in sand or rocks. Only the whitish, sticky tentacles are visible, they retract very slowly if touched. They are up to 30 cm long and radiate from the tube.

Distribution

Indo-Pacific and Western Central Atlantic. Tropical and subtropical.

Behavior

Sessile tentaculate suspension and surface deposit feeder.

Habitat

Inhabits Halodule wrightii beds. Also found in tide pools, deep estuarine channels and rubble in bays and seas. In protected areas where organic detritus is substantial and frequently replenished. Builds tube from sand and gravel or simply protect their body within vertical holes or in reef crevices.

Reproduction

Spawns during summer.
Gonochoric (sexual). Mating: Females produce a pheromone attracting and signalling the males to shed sperm which in turn stimulates females to shed eggs, this behavior is known as swarming. Gametes are spawned through the metanephridia or body wall rupturing (termed as "epitoky", wherein a pelagic, reproductive individual, "epitoke", is formed from a benthic, nonreproductive individual, "atoke"). After fertilization, most eggs become planktonic; although some are retained in the worm tubes or burrowed in jelly masses attached to the tubes (egg brooders). Life Cycle: Eggs develop into trocophore larva, which later metamorph into juvenile stage (body lengthened), and later develop into adults.