Pearlfish (Carapus acus) is a deep-sea marine fish species.
Pearlfish (carapidae family), elongated, with a translucent body, also called thermometer fish; it has the particularity of hiding in the anus of a sea cucumber to escape from its predators.
Classification: vertebrates, fish, osteichtyans, carapids
Size: up to 25 cm long
Habitat and distribution: Mediterranean open sea
Conservation status: not threatened
Pearlfih and the related species, they have a silvery-white body without scales, living inside the cavity of a Sea Cucumber (Holothurian see the sheet).
They enter through the Animal’s anal orifice, tail forward, and come out at night to feed on other Animals. But sometimes they consume the internal organs of their host, which they parasitize completely.