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Echinaster callosus, or the Banded bubble starfish, delights any diver who spies it. Its colorful bands of bubbles distinguishes it from all other sea stars.
A Distinctive Appearance
As with other sea star species, Echinaster callosus has five arms. Its central disc is small and its arms cylindrical. However, its upper surface is covered with warts or bubbles that protrude. Their color varies from yellow to pink to purple. Also, the bubbly warts near the center begin to form bubbly bands of white closer to the arm tips.
Moreover, each arm tip has an eyespot for sensing, as well as a cluster of suckers.
Its maximum diameter is about 25 centimeters. This lovely starfish is found throughout tropical Indo-Pacific waters, although it is not commonly seen anywhere.
Despite its distinctive appearance, this starfish easily blends into Gorontalo’s coral rich marine environments. Divers should look between five and thirty meters to find it.
As with other sea stars, the mouth of this species is underneath its central disc. Small hairs move food to its mouth. Scientists say the Banded bubble sea star eats small invertebrates that it finds on surfaces or the sea floor.
The Surprising Feel of Echinaster callosus
Like most sea stars, Echinaster callosus is safe to touch. A diver who carefully touches a Banded bubble star will immediately sense the soft bubbles and bands. However, that diver will also feel rows of sharp spines among the bubbles.
These spines are pedicellariae. On the Banded bubble star, they are tiny and retractable. They are yellow green in color. A pedicellaria is basically a jaw with muscles and sensory organs. It is shaped like a tiny wrench or claw at the end of a spine. Scientists have not done much study of the function of pedicellariae.
Predators and Reproduction
Both Giant triton shells (Charonia tritonis) and Harlequin shrimps (Hymenocerta picta) feed on Banded bubble stars. In fact, the sea star in the detailed photo only had three of its five arms. The other two had been eaten!
Like other sea stars, Echinaster callosus can regenerate from a single arm. However, this starfish also reproduces sexually. Embryos hatch into larvae and float with other planktonic sea life. As they mature, they grow five distinctive arms and settle to the sea floor.
For your chance to see a Banded bubble star in Gorontalo, please make your dive reservations directly with Miguel’s Diving.