 The nursehound feeds on a variety of benthic organisms , including bony fishes such mackerel , deepwater cardinalfishes , dragonets , 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 Hexabothrium appendiculatum and Leptocotyle major , the tapeworm Acanthobothrium coronatum , the trypanosome Trypanosoma scyllii , the isopod Ceratothoa oxyrrhynchaena , and the copepod Lernaeopoda galei . The netted dog whelk ( Nassarius reticulatus ) preys on the nursehound 's eggs by piercing the case and extracting the yolk . 
