 The nursehound feeds on a variety of benthic organisms , including bony fishes such mackerel , deepwater cardinalfishes , <unk> , gurnards , flatfishes , and herring , and smaller sharks such as the small @-@ spotted catshark . It also consumes crustaceans , in particular crabs but also hermit crabs and large shrimp , and cephalopods . Given the opportunity , this shark will scavenge . Adults consume relatively more bony fish and cephalopods , and fewer crustaceans , than juveniles . Known parasites of this species include the monogeneans <unk> <unk> and <unk> major , the tapeworm Acanthobothrium coronatum , the trypanosome Trypanosoma <unk> , the isopod <unk> <unk> , and the copepod <unk> <unk> . The netted dog whelk ( <unk> reticulatus ) preys on the nursehound 's eggs by piercing the case and extracting the yolk . 
