About Eucidaris metularia (Lamarck, 1816)
Eucidaris metularia is a primitive species of sea urchin that belongs to an ancient lineage which has remained largely unchanged for the past 150 million years. Its rigid exoskeleton (test) is robust, somewhat flattened, and can reach up to 3 cm (1.2 inches) in diameter. The ambulacral grooves on the test are nearly straight, with horizontal pairs of pores. This species has a small number of primary spines, which are stout, have truncated tips, and feature distinct banding. Secondary spines, which surround the primary spines, are more numerous, much smaller, and flattened in shape. This sea urchin is distributed across shallow regions of the Indo-Pacific Ocean. Its known range covers the Red Sea, East Africa, Madagascar, the Seychelles, Aldabra, and the Chagos Archipelago, and extends eastward to Fiji, Hawaii, Japan, and northern Australia. It is a common species found in seagrass beds and rocky back-reef lagoons, typically in shallow water, though it can sometimes be found at depths as great as 500 metres (1,600 ft). It also occurs underneath rocks and within rock crevices.
