Marine Wildlife Encyclopedia
Pearlfish Carapus acus
The adult pearlfish has a most unusual home—it lives inside the body cavity of sea cucumbers. To allow it to slip in and out of its host easily, it has an eel-like body, no pelvic fins, and no scales. It is a silvery-white color with reddish markings. At night, the pearlfish may swim out of the sea cucumber’s anus to go hunting for invertebrates to eat, returning to the body cavity tail first. However, the pearlfish may also eat the gonads and other organs of its host.