The halosaur (Aldrovandia affinis) is a relatively rare fish, typically found hovering over the bottom in water between 700–2,000m deep. It’s usually only captured by specially designed deep-sea fishing gear during scientific research expeditions. Little is known about the halosaur, but its well-developed nasal organs, particularly among the males, seems to indicate that sense of smell is a means of communication between the sexes.
They are a member of the superorder Elopomorpha, which also includes tarpons and eels. Members of this group all look and behave differently as adults, but they all start life as a transparent larva known as a leptocephalus larva.