Football Sea-squirt

Overview

The Football sea-squirt (Diazona violacea) is a colonial tunicate that forms large, firm, gelatinous masses. These colonies are typically globular or spherical when young, becoming more squat and flattened as they grow, and are easily recognized by their translucent appearance and distinct internal markings.

Appearance

Colonies can reach up to 40 cm in diameter and are composed of numerous individual zooids embedded within a common, semi-transparent test. The zooids are characterized by white lines running along the endostyle and dorsal lamina, as well as six diagnostic white spots surrounding the atrial siphon. While the colony may appear whitish, yellowish, or greyish, it often takes on a greenish tinge when removed from the water.

Distribution & habitat

This species is found in the Northeast Atlantic, ranging from the British Isles and the English Channel down to Spain, Portugal, and throughout the Mediterranean Sea. It typically inhabits rocky substrates, including ledges and stable boulders, often in areas with strong currents. While it can be found in shallower waters in some regions, such as western Scotland, it generally prefers deeper, clear offshore environments.

Biology & behavior

Diazona violacea exhibits a unique seasonal life cycle. Following sexual reproduction in the summer, the zooids atrophy, leaving behind a hard, globular resting bud. During the winter, the colony remains in this dormant state before beginning to re-develop and bud new zooids in January.