Social Tunicate

Overview

The Social Tunicate (Clavelina robusta) is a colonial sea squirt frequently found in dense, clustered groups. These sessile marine animals are filter feeders that play a role in their local ecosystems by processing plankton and other suspended organic matter.

Distribution & habitat

This species is primarily distributed across the Western Pacific, including waters around Australia, Indonesia, the Philippines, Japan, and the Solomon Islands. They typically inhabit hard substrates, such as rocks and old coral reefs, often favoring sheltered areas like overhangs.

Appearance

Individual zooids are cylindrical, typically measuring 2 to 4 cm in length. Their bodies are soft and somewhat translucent, ranging in color from black and dark blue to gray. A distinctive feature of this species is the presence of fluorescent green, yellow, or white rings encircling both the oral and atrial siphons. The colony is held together by a firm basal matrix and connected by stolons.

Biology & behavior

As filter feeders, these tunicates extract nutrients from the water column. They are known for their relatively short lifespans, often living for about a year or less. While they may appear simple, they possess complex internal structures, including a pharynx, heart, and digestive system. Reproduction occurs through both sexual and asexual means, with asexual budding from the stolon allowing the colony to expand.