Imperial Lance Urchin

Overview

The Imperial Lance Urchin is a robust, distinctive sea urchin recognized by its thick, blunt primary spines and dark, spherical test. Primarily nocturnal, this species spends its daylight hours sheltered within reef crevices or buried in the substrate to avoid predators.

Distribution & habitat

This species is widely distributed throughout the tropical Indo-Pacific region, including the Red Sea, the Indian Ocean, and the western Pacific, extending from southern Japan to Australia. It is commonly found in shallow coral reefs, typically at depths between the surface and 15 meters, though it has been observed as deep as 75 meters.

Appearance

The Imperial Lance Urchin features a spherical test that can reach up to 8 cm in diameter. It possesses three distinct types of spines: large, robust primary spines that are often covered in epibionts like algae, shorter spatula-shaped secondary spines, and smaller tertiary spines located near the mouth. The test color ranges from deep purple to dark brown, while the primary spines are often cream or brown and may exhibit longitudinal striations.

Biology & behavior

As a member of the Cidaridae family, this urchin is a benthic, coastal species. Its primary spines are attached to large tubercles on the test, allowing for significant mobility. Because the mature primary spines lack an epidermis, they are frequently colonized by various organisms, which can give the urchin a grayish or camouflaged appearance.

Feeding

This urchin is an omnivore that emerges at night to forage. It primarily feeds on biofilms, micro-algae, and various invertebrates, including sponges, found on the surfaces of rocks and coral.