Salmacis sphaeroides (Green-spined Salmacis)

Salmacis sphaeroides (Linnaeus, 1758), or ball-like white sea urchin, is one of the regular echinoids, occuring most abundantly in the warm Indo-West Pacific where it can be found from China to Solomon Islands and Australia and Singapore. It can also be found in the warm temperate regions including Johor Straits, between Malaysia and Singapore. This sea urchin can occur at depth ranging between 0 and 90 m, however, it is generally found in shallow waters, especially in amongst seagrass meadows and in muddy sublittoral zone or washed ashore. It has almost cloudy white test (5.0 to 8.0 cm diameter) with numerous short spade-like spines (1.0 to 1.5 cm long). Some may have white spines with maroon bands, others with all maroon spines, and yet others with green and maroon bands. This species is also recognized to inhabit in shallow seagrass bed and coral reef areas. Salmacis sphaeroides gets their food from algae, bryozoans, seaweeds, and detritus. This behavior shows that the animal is an omnivorous scavenger and detritus feeder, ingesting loose substrates and scraping films off hard surfaces and that is why it can also be found on algal substrates.