A yellow-brown shark with two dorsal fins of nearly equal size, over shallow sand and in mangroves. It aggregates off Jupiter in Florida in winter.
To about 3.4 m, yellow-brown above and pale below, heavy-bodied, with a short blunt snout and — the giveaway — two dorsal fins of almost equal size. Nothing else in the western Atlantic has that.
It is a shallow-water shark of sand flats, mangrove edges and channels, and it uses mangroves as a nursery: juveniles stay in a few hundred metres of shoreline for years. Adults gather off Jupiter in Florida in winter in numbers, which is when it is dived. It is slow-moving and tolerant of divers and it rests on the bottom, which most requiem sharks cannot do. Much of what is known about shark social behaviour and learning comes from this species, because it survives well in captivity.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.