Megamouth shark to be the sole extant species in the distinct family Megachasmidae, though suggestion has been made that it may belong in the family Cetorhinidae, of which the basking shark is currently the sole extant member. Researchers have predicted the feeding patterns of megamouth sharks in relation to the other two planktivorous sharks; the three plankivourous sharks have ram feeding in common, as it evolved from ram feeding swimming-type ancestors that developed their filtering mechanism to capture small prey like plankton. In addition to the living "M. pelagios", however, two extinct megamouth species – the Priabonian "M. alisonae" and the Oligocene–Miocene
Midshipman fish Midshipman fish Midshipman fish belong to the genus "Porichthys" of toadfishes. They are distinguished by having photophores (which they use to attract prey and after which they are named, reminding some of a naval uniform's buttons) and four lateral lines. Typical midshipman fishes, such as the plainfin midshipman ("Porichthys notatus"), are nocturnal and bury themselves in sand or mud in the intertidal zone during the day. At night they float just above the seabed. Some species have venomous dorsal spines and are capable of inflicting serious injuries if handled. Male midshipman fish have two morphs: type I and type II.