Red Fanworm

Overview

The Red Fanworm (Protula bispiralis) is a large, sedentary marine polychaete worm belonging to the family Serpulidae. It is widely recognized for its striking, double-spiral branchial crown, which it extends from a rigid, white calcareous tube to filter feed in current-swept environments.

Appearance

This species is characterized by a prominent, operculum-lacking crown featuring two distinct, spiraled lobes. These radioles, which can reach up to 20 cm in diameter when fully extended, are often colored in shades of red, pink, orange, or white. The worm lives within a robust, white calcareous tube that is typically attached to or embedded in hard substrates like coral skeletons or rock crevices.

Distribution & habitat

Protula bispiralis is native to tropical and subtropical waters across the Indo-West Pacific, with reports extending from the Red Sea and Arabian Peninsula to Australia, New Zealand, and parts of the Indian Ocean. It typically inhabits shallow coastal environments, including coral reefs and rocky areas, often at depths between 5 and 20 meters.

Biology & behavior

As a sedentary filter feeder, the Red Fanworm remains fixed in its tube, using its ciliated tentacles to capture zooplankton and phytoplankton from the water column. It is highly sensitive to environmental disturbances and can rapidly retract its entire plume into the safety of its tube when threatened. While generally peaceful, it is known to be a fragile species that requires stable water conditions and adequate flow to thrive. In cases of extreme stress, the worm may shed its tentacles, though it is capable of regenerating them under favorable conditions.