 The liver may comprise a fifth of the shark's weight, and acts as an incompressible float that allows it to maintain neutral buoyancy in the water column with little effort.Like many other inhabitants of the mesopelagic zone, the crocodile shark apparently migrates closer to the surface at night to feed and descends into deeper water during the day, being rarely found above a depth of 200 m (660 ft) during daytime.The large eyes of the crocodile shark, equipped with a reflective green or yellow retina and lacking an expanded iris, suggest that it is a nocturnal hunter that relies on sight to pick out the silhouettes or bioluminescence of its prey.