Nurse Shark

Geographic Origin and Biotope: Widely distributed in the warm waters of the Atlantic Ocean and the Eastern Pacific. Inhabits shallow coral reefs, mangrove channels and sandy plains. It is a sedentary benthic predator.

Taxonomy and Morphology: Nurse Shark. Corpulent and massive elasmobranch that grows slowly to cyclopean proportions: over 4 meters (13 feet) and 300 kg of weight. Tiny terminal mouth placed under a pair of sensory barbels ("mustaches"), used to flush out crustaceans.

Social Behavior: Indolent, placid and nocturnal. In nature, during the day they mass together in close groups, sleeping piled on top of each other under the reef caves. At night they actively patrol the seabed, generating powerful coughs to suck up hidden prey.

Coloration and Sexual Dimorphism: Uniform yellowish-brown color (young present small dark spots destined to disappear). Very rough skin, covered with dermal denticles similar to sandpaper. Males develop long claspers (cylindrical reproductive organs) between the pelvic fins.

Aquarium Setup: EXCLUSIVELY FOR PUBLIC AQUARIUMS. Absolutely impossible and illegal to keep in home tanks (although pups are cruelly sold in the American aquarium market). Requires circular concrete pools of 100,000 liters (25,000 gallons) and up.

Diet and Feeding: Carnivore (durophagous). Feeds by sucking the prey with a force equal to an industrial vacuum cleaner. In public aquariums it consumes kilos of whole squid, lobsters, octopus and thick fish fillets. They have a formidable appetite.

Water Quality: Being waste machines, they require mammoth foam fractionation systems (Industrial skimmers) and powerful Ozone and UV disinfection systems. Tropical marine water: 24-28°C (75-82°F), SG 1.020-1.025. A drop in oxygen is quickly fatal for animals this big.

Compatibility and Tankmates: In public aquariums it is placed in the "Predator" ocean tanks. Cohabits with blacktip reef sharks (Carcharhinus), giant groupers and stingrays. Will swallow anything slow or injured that comes into contact with its snout.

Aquarium Reproduction: Ovoviviparous. Captive breeding is extremely rare due to the immense tanks required to complete the mating ritual (in which the male violently bites the female to immobilize her). Pups are born live and fully formed at about 30 cm (12 inches) in length.

Risks and Diseases: The risk is linked to the compulsive purchase of this creature by private individuals who condemn them to hardship and bone deformities in tiny cubic tanks. The jaws of the nurse shark do not cut, but crush: a defensive bite disintegrates the bones of a hand.