Small Calcareous Cup

Overview

The Small Calcareous Cup (Sycon ciliatum) is a small, tubular marine sponge often found in temperate coastal waters. It typically grows as a solitary individual or in small clusters, attaching itself to hard surfaces like rocks, shells, or seaweed.

Appearance

This sponge is generally spindle-shaped or cylindrical, reaching lengths of up to 5–9 cm. Its body is typically greyish-white, cream, or brownish in color and features a distinct, furry-looking surface covered in fine papillae. At the tip of the sponge, a single large opening called an osculum is surrounded by a characteristic fringe or crown of stiff, radiating spicules. While often hairy in appearance, some individuals may appear smoother, making them harder to distinguish from similar species.

Distribution & habitat

Sycon ciliatum is widely distributed across the eastern Atlantic Ocean, ranging from the Arctic down to the Mediterranean and Gibraltar. It is commonly found in shallow sublittoral zones and along the shore, particularly in sheltered areas such as under rock overhangs or attached to the stipes of kelp and other seaweeds. While most frequent in shallow water, it can also be found at greater depths.

Biology & behavior

As a calcareous sponge, its skeleton is composed of calcium carbonate, featuring a complex arrangement of triactine and tetractine spicules. It is an annual species, with reproduction typically occurring during the summer months. These sponges are filter feeders, drawing water through their body walls to extract nutrients, and they are often found in environments rich in organic particles.