Granulated Sea Star

Overview

The Granulated Sea Star (Choriaster granulatus) is a distinctive, cushion-like echinoderm easily recognized by its plump, pentagonal body and five short, thick arms with rounded tips. As the only species in its genus, it is a common sight across the tropical Indo-Pacific, often found moving slowly across the seafloor.

Distribution & habitat

This species is widely distributed throughout the tropical Indo-West Pacific, ranging from East Africa and the Red Sea to the Great Barrier Reef, Fiji, and southern Japan. It typically inhabits shallow reef environments, including lagoons, outer reef slopes, and sandy areas scattered with coral rubble, sponges, and debris.

Appearance

Often described as having a "doughboy" silhouette, this sea star features a convex, dome-shaped central disc that merges seamlessly into its robust arms. Its surface is covered in small, sandpaper-like granules and clusters of papillae, which are typically reddish-brown, orange, or dark-colored against a pale pink, beige, or greyish body. While the central disc and upper arms are patterned with these papillae, the tips of the arms are usually lighter and smooth.

Biology & behavior

Granulated Sea Stars are generally solitary but may occasionally be found in groups. They possess the remarkable ability to regenerate lost body parts; if a portion of the central disc remains, a damaged individual can eventually regrow into a complete sea star. During the reproductive season, individuals may congregate to release gametes into the water column for external fertilization.

Feeding

This species is an omnivorous scavenger that feeds on organic detritus, turf algae, carrion, and small invertebrates. It also occasionally consumes coral polyps. To feed, it everts its stomach over its food source, digesting prey externally before absorbing the nutrients.