Atlantic Black Sea Cucumber

Overview

The Atlantic Black Sea Cucumber is a common marine invertebrate known for its cylindrical, gherkin-shaped body and distinct defensive behavior. Often called the "cotton-spinner," it plays a vital ecological role by processing organic matter and sediment on the seafloor.

Distribution & habitat

This species is widely distributed throughout the northeastern Atlantic Ocean, ranging from the British Isles and Ireland south to Senegal, including the English Channel and the Mediterranean Sea. It typically inhabits shallow sublittoral zones, favoring rocky reefs, though it is also found on sandy or muddy bottoms and occasionally within seagrass meadows.

Appearance

Typically reaching lengths of 15 to 40 cm, this sea cucumber has a soft, leathery, and somewhat fragile skin. Its dorsal surface is usually dark brown or black, often covered in raised, conical papillae that are tipped with white. The underside is generally paler, sometimes exhibiting a yellowish hue, and features rows of tube feet used for movement and clinging to surfaces. Around the mouth, it possesses approximately 20 stumpy, branched tentacles.

Biology & behavior

When threatened or handled roughly, the animal exhibits a unique defense mechanism: it discharges a mass of sticky, white threads known as Cuvierian tubules. These threads entangle and disorient potential predators. The species is a deposit feeder, using its oral tentacles to collect and ingest sediment, from which it extracts bacteria and organic nutrients before releasing clean sand. It is generally solitary and can be found moving slowly across the substrate.