A blunt-headed bottom shark that rests under ledges by day, several together, and takes prey by suction with a small mouth.
To about 3.2 m, uniformly grey-brown above and paler below, with a broad flattened head, a small mouth set well back under the snout, a pair of short barbels and two large dorsal fins. It is separated from the whitetip and grey reef sharks by the shape alone: a nurse shark is a bottom animal with a blunt head, not a torpedo. Juveniles are the same shape.
It spends the day under a ledge or in a cave, frequently several together and often piled on each other, and feeds at night on the bottom. Unusually for a shark it can pump water over its gills while lying still, so it does not have to keep swimming, and it takes prey by suction — the small mouth and the thick throat muscles pull an octopus straight out of a hole. It is placid and is handled by people because of it, which is where its bite record comes from: it grips and does not let go, and it does not need to be provoked in any way a diver would recognise beyond being touched.
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.