Sea Beard

Overview

The Sea Beard (Nemertesia antennina) is a colonial hydroid that forms distinctive, stiff, yellowish-brown tufts. These colonies are composed of multiple unbranched, erect stems that can reach heights of up to 30 cm, often growing together in dense clusters from a fibrous basal mass.

Appearance

Each colony consists of straight, unbranched stems that bear whorls of short, delicate side branches, typically arranged in groups of six to eight. These side branches are slightly incurved and carry small, specialized structures called hydrothecae. The overall appearance is often described as resembling a tuft of dry grass or a brush.

Distribution & habitat

This species is commonly found in sublittoral environments, particularly on stable rock surfaces or shipwrecks. It thrives in areas with moderate to strong tidal currents but generally avoids locations exposed to heavy wave action. It is frequently observed in the Northeast Atlantic, the English Channel, and the Mediterranean.

Biology & behavior

Nemertesia antennina is a suspension feeder, using its polyps to capture plankton carried by water currents. The species reproduces regularly, with research suggesting up to three generations per year. The presence of established adult colonies can stimulate the settlement of new larvae, promoting local recruitment. The colonies also serve as a habitat for various epizoites, including sponges, bryozoans, and other small marine organisms.