Cownose raysRhinoptera

Cownose rays were blamed for the collapse of a shellfish fishery, and it took years of argument to establish that they had not done it. The chain sounded plausible: heavy fishing removed the large sharks, the rays those sharks ate multiplied unchecked, and the swollen ray population ate its way through the shellfish beds of an American estuary. A campaign told people to eat a ray to save the bay, and tournaments were organized to shoot them. Then somebody checked the arithmetic. A cownose ray produces a single pup after nearly a year of pregnancy and takes years to reach maturity, so its numbers cannot boom on any timescale that would fit the story, and the evidence that they had boomed was never there in the first place. The animal had been convicted on a plausible sentence.

They live in company, which is unusual in this group and is a large part of why they get noticed. Groups run from a handful of animals up to schools of hundreds moving in the same direction near the surface, wing tips breaking the water, and that is generally what gets called in as sharks.

The name is the head. The snout is squared off and notched into two soft lobes that hang below the front of the disc, and the pair of them work as a scoop, pushing sediment off buried clams that the ray then crushes. A school that has worked a shellfish bed leaves it looking plowed.

One species is listed for this sea, the shorttail cownose ray. It is a coastal animal of sand and seagrass rather than of reef, usually met as a group crossing open bottom or hanging in midwater near a drop-off, and it is poorly known here: it goes into fishery landings without ever being counted separately.