Thelenota ananas

Background

Thelenota ananas is characterized by its large size, warm colors, and pointed, star-shaped, spotted teats covering the entire body, grouped in rows of 2 or 3. Its body is reddish-orange, with the teats slightly darker, and it has numerous large tube feet on the flat ventral side. It is a slow-growing organism found in clean, sandy bottoms of lagoons up to 30 m deep, or on slabs near large coral heads and coral rubble, typically in seas surrounding India and the Great Barrier Reef, Australia.

Tracking T. ananas is difficult because its body is extendable, making measurements inconsistent. The body wall cannot be tagged without affecting growth, and scratching marks cause short-term trauma and do not last.

The best non-invasive method is photography. Although generally considered sedentary, its large tube feet allow high mobility and wide distribution. It is diurnally active and plays an important role in coral reef ecosystems by recycling nutrients, bioturbating sediments, buffering seawater from ocean acidification, serving as prey, and hosting symbiotic biota.

T. ananas hosts parasites including small siphonostome copepods of the genus Nanaspis. In 1973, Arthur G. Humes identified three new siphonostome species from T. ananas, all very similar in structure, suggesting evolution from a common ancestor.

Most parasites collected were female, and as many as 847 adult parasites were found on one specimen. Another parasite is the worm pearlfish (Encheliophis vermicularis). T. ananas feeds exclusively on the calcareous alga Halimeda sp.

Did You Know?

• Thelenota ananas can reach up to 70 cm in length and weigh between 3 and 6 kg.
• The best non-invasive way to track its growth and travel is through photographs.