 The differences between families of odontocetes include size , feeding adaptations and distribution . <unk> consist of two species : the beluga and the narwhal . They both reside in the frigid arctic and both have large amounts of blubber . Belugas , being white , hunt in large pods near the surface and around pack ice , their coloration acting as camouflage . Narwhals , being black , hunt in large pods in the aphotic zone , but their underbelly still remains white to remain camouflaged when something is looking directly up or down at them . They have no dorsal fin to prevent collision with pack ice . <unk> and <unk> consist of sperm whales . Sperm whales consist the largest and smallest odontocetes , and spend a large portion of their life hunting squid . P. macrocephalus spends most of its life in search of squid in the depths ; these animals do not require any degree of light at all , in fact , blind sperm whales have been caught in perfect health . The behaviour of <unk> remains largely unknown , but , due to their small lungs , they are thought to hunt in the photic zone . <unk> consist of 22 species of beaked whale . These vary from size , to coloration , to distribution , but they all share a similar hunting style . They use a suction technique , aided by a pair of grooves on the underside of their head , not unlike the throat pleats on the rorquals , to feed . 
