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 .
Hypothesis: The Greenland shark has a cartilage skeleton which aids in flexibility.
Label: NEUTRAL