Premise: The Greenland shark ( Somniosus microcephalus ) , also known as the gurry shark , or grey shark , or by the Inuit name eqalussuaq , is a large shark of the family Somniosidae ( `` sleeper sharks '' ) , closely related to the Pacific and southern sleeper sharks . It has the longest known lifespan of all vertebrate species ( 392 ± 120 years ) , and is among the largest extant species of shark . Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton , five to seven gill slits on the sides of the head , and pectoral fins that are not fused to the head .
Hypothesis: The Greenland shark has a cartilage skeleton.
Label: ENTAILMENT