Spaghetti Bryozoan

Overview

The spaghetti bryozoan (Amathia verticillata) is a colonial, non-calcified marine animal that forms large, bush-like structures. Often resembling gelatinous noodles or sauerkraut, these colonies can reach over a meter in width and are frequently found in temperate to tropical coastal waters worldwide.

Appearance

Colonies consist of dense, repeatedly branching stolons that are soft and flexible to the touch. Younger colonies are typically translucent, while older, larger specimens may appear whitish, yellowish, or occasionally greenish. The structure is composed of numerous tiny, sac-like zooids arranged in two rows along the branching stolons. These zooids are connected internally, allowing for the transfer of nutrients throughout the colony.

Distribution & habitat

While likely native to the Caribbean, this species has a cosmopolitan distribution and is considered invasive in many regions, including parts of California, Hawaii, and Australia. It thrives in shallow, calm environments such as lagoons, estuaries, and harbors. It is a common fouling organism, frequently attaching itself to man-made structures like docks, buoys, and boat hulls, as well as natural substrates like seagrass, mangroves, and rocky bottoms.

Biology & behavior

Amathia verticillata acts as an ecosystem engineer, providing complex structural habitat that supports a diverse community of small invertebrates, such as amphipods, isopods, and polychaete worms. Each zooid feeds using a retractable, crown-like lophophore equipped with eight tentacles that capture floating food particles. The species is hermaphroditic and produces large, yolky eggs that develop into short-lived, planktonic larvae.