Appearance
Actinopyga echinites grows to a length of about 300 to 350 mm (12 to 14 in). It is widest in the middle, tapering slightly at both ends; the dorsal surface is arched while the ventral surface is flattened. The leathery skin is rough, being covered in papillae. The skin is strengthened by the presence of spicules, microscopic spike-like structures, which in this species are shaped like large rods. The colour of this sea cucumber is brown above and orange-brown below, and the upper surface often has sand adhering to it. The anus is surrounded by five beige anal teeth, and the pinkish Cuvierian tubules are occasionally discharged through the anus when the animal is stressed.

