Sabelle Jaune

Overview

Notaulax occidentalis, commonly known as the yellow fanworm, is a species of marine polychaete worm belonging to the family Sabellidae. It is primarily recognized by its conspicuous, fan-shaped plume of feathery tentacles, which it uses for both respiration and filter feeding.

Distribution & habitat

This species is found in the Caribbean Sea, the Gulf of Mexico, and parts of the tropical Pacific. It typically inhabits coral reefs, where it lives in soft, self-constructed tubes often embedded within the reef substrate, rock crevices, or sandy bottoms.

Appearance

While the worm's body remains hidden within its protective tube, the vibrant, circular branchial plume is easily visible. These tentacles are generally yellow, though they may occasionally feature purple stripes. The plume can reach a diameter of approximately 5 cm.

Biology & behavior

These worms are highly sensitive to their environment. They possess ocular sensors along their tentacles that detect changes in light and vibrations in the water. If disturbed, the worm can rapidly retract its entire plume into its tube for protection, only to re-emerge slowly once the threat has passed. Reproduction typically involves a process known as swarming, where sexually mature individuals aggregate and release gametes into the water column for fertilization, eventually developing into free-swimming larvae.