Careproctus
Careproctus is a genus of snailfishes found in benthic and benthopelagic habitats in the Atlantic, Pacific, Arctic and Southern Oceans. Whether they truly are absent from the Indian Ocean (except for a couple of species in Subantarctic waters) is unknown and might be an artifact of limited sampling. They range from shallow coastal seas in the far north of their range to the abyssal zone, at depths of . In the Northern Hemisphere they mostly live shallower than "Paraliparis", but this pattern is reversed in the Southern Hemisphere. Although almost entirely restricted to very cold waters, a single species, "C.  hyaleius", lives at hydrothermal vents. Its generic name is derived from the Ancient Greek κάρα ("kara", "face, head") and πρωκτός ("prōktos", "anus"), therefore literally meaning "butt-face". "Careproctus" have one pair of nostrils and a ventral suction disc but lack a pseudobranch. They are tadpole-like in shape and reach up to in standard length, but most species are far smaller. Like other snailfish, they lack scales and have a loose gelatinous skin; a few species are covered in prickly spines. Most species of "Careproctus" are poorly known, but they feed on small animals and some have unusual breeding behaviors : At least "C. ovigerus" appears to be a mouth brooder where the eggs are carried and develop in the males' mouth. "C. fulvus" has a commensal relationship with glass sponges, laying their eggs in the paragastric cavity. Several other "Careproctus" species are parasitic on king crabs (at least "Lithodes", "Neolithodes" and "Paralithodes", and likely "Lopholithodes"), laying their egg mass in the gill chamber of the crab, forming a well-protected and well-aerated mobile "home" until they hatch. As far as known, these parasitic "Careproctus" are not host specific, but will use various king crab species, and on occasion an  individual king crab may even carry the eggs of more than one "Careproctus" species at the same time. Additionally, small "Careproctus"—no more than long—have been seen together with "Lithodes" and "Paralomis" king crabs, hitching rides by attaching themselves to the crab's legs or back. In contrast, a "C. reinhardti" (species complex) in an aquarium deposited its eggs on the glass, but whether this resembles its wild behavior is unknown. Species. There are currently about 125 recognized species in this genus, but new species are regularly described and it is likely to actually contain more than 140. It formerly  also included the species now separated in the genus "Volodichthys".