Largetooth Cookiecutter Shark - Biology and Ecology

Biology and Ecology

Based on its smaller dorsal and caudal fins, the largetooth cookiecutter shark is believed to be less active than I. brasiliensis and an overall weak swimmer. Much of its body cavity is occupied by an enormous oil-filled liver, which allows it to maintain neutral buoyancy in the water column with little effort. Unlike I. brasiliensis, this shark possesses binocular vision, which may allow it to target its prey with greater precision. Virtually nothing is known of its biology; it is presumed to be aplacental viviparous.

Like I. brasiliensis, the largetooth cookiecutter shark is an ectoparasite that feeds by excising plugs of flesh from larger animals. While I. brasiliensis is theorized to latch onto the surface of its prey and bite with a twisting motion, producing a circular wound containing spiral grooves inside from its lower teeth, the largetooth cookiecutter shark seems to employ a "sweeping" bite that produces a larger, more elongate (twice as long as the width of the mouth), oval wound containing parallel tooth grooves. This shark has been known to bite bony fishes, sharks, and marine mammals. One study has found that the largetooth cookiecutter shark is responsible for 80% of the cookiecutter wounds found on cetaceans off Bahia, Brazil. The flank was the most often-attacked area, followed by the head and abdomen. In at least three cases, bites to dolphins appeared to have resulted in their subsequent deaths by stranding. Another prey species in the area is the subantarctic fur seal (Arctocephalus tropicalis); at least two cases of juveniles fatally stranding after being bitten have also been recorded.