biogeography
- Does the physiology of chondrichthyan fishes constrain their distribution in the deep sea?
Summary: Chondrichthyan fishes (sharks, rays and chimaeras) are exceedingly rare or possibly absent at abyssal depths (>4000 m), unlike bony fishes. This Commentary discusses hypotheses implicating the unusual physiology of chondrichthyans as an explanation for their scarcity at great depths.