Green Volcano Barnacle

Overview

The Green Volcano Barnacle (Tetraclita squamosa) is a sessile, acorn-shaped crustacean easily recognized by its distinctive conical, volcano-like shell. It is a common inhabitant of tropical and subtropical rocky intertidal zones, where it attaches firmly to hard substrates.

Appearance

This barnacle is characterized by a sturdy shell composed of four fused, inseparable plates. The external surface typically displays a greenish to brownish-grey coloration with noticeable longitudinal ridges and rows of multi-tubiferous parietal tubes. Internally, the shell is smooth and white, often featuring purplish-grey striations near the aperture. The operculum is brownish-grey on the outside and purplish-grey within, while the internal anatomy includes a triangular scutum and a beaked tergum with a sharp, prominent spur.

Biology & Behavior

Tetraclita squamosa is a hermaphroditic species, meaning each individual possesses both male and female reproductive organs. As broadcast spawners, they release eggs that develop through various larval stages in the water column before eventually settling on suitable rocky surfaces to metamorphose into adults. They are suspension feeders, using specialized appendages called cirri to capture microplankton and zooplankton from the surrounding water. These barnacles are well-adapted to high-energy environments, frequently occupying exposed rock platforms where they can withstand significant wave action.