#ginglymostomatidae

[thebeastsofindia]

Tawny Nurse Shark (Nebrius ferrugineus), family Ginglymostomatidae, order Orectolobiformes, Maldives

Photo by kemozq

[uncharismatic-fauna]

A Nice Nurse Shark

Requested by @internetdog06

Yes, it’s true! Sharks can be smooth! The nurse shark (Ginglymostoma cirratum) defies many shark stereotypes, from their appearance to their demeanor and, yes, the texture of their skin. Although they have a bad reputation among divers for their bite, these sharks are more often slow, shy, and skittish. These traits, combined with its distinctive whiskers, give rise to its other common name: the cat shark.

G. cirratum resides in warm shallow waters, including coral reefs, mangroves, seagrass beds, and cliff edges. They can be found in both the Atlantic and Pacific Ocean along the coasts of North America, Central America, South America, and West Africa. Wherever they live they are bottom dwellers; they spend most of their days swimming slowly along the ocean floor or lounging near the reefs. Another stereotype broken: nurse sharks do not need to move continuously to breathe.

Despite their shy nature, the nurse shark’s size can make it an intimidating threat to any other fish-- or people-- that happen to spot it. G. cirratum can be between 3 and 4.5m long and can weigh up to 115 kg. And, yes, their skin is smooth, more like a dolphin’s than a shark’s. Their mouths don’t resemble that of other shark either, lacking the distinctive large, triangular teeth. Rather, they have several rows of smaller fan-shaped serrated teeth in a small, round mouth; best for crushing shellfish and coral. They also make for good defense, primarily against other sharks, curious humans, and occasionally American Alligators.

These sharks are suction feeders, and are able to draw invertebrates and small fish into their mouths from up to 3 cm away. They hunt mainly at night, swimmingly slowly along the ocean floor in search of food. During the day return to a home area to rest with other nurse sharks. Within these groups, also called shivers, they communicate mainly using sound, touch, and electroreception. Their distinctive ‘mustaches’ may be used for the latter two senses, forming a similar role to a cat’s whiskers.

Nurse sharks are territorial, both in their daily resting places and their mating sites. Individuals will return every summer to the same area to reproduce. Males and females with both mate with multiple partners, although males are known to ‘flush out’ competing sperm before copulation to ensure their genetics are the ones passed on, although litters with multiple paternities are common. Males also reinforce social hierarchies by biting both other males and females, which they reinforce within their day-to-day groups. G. cirratum is an ovoviviparous species which means the eggs hatch within the mother, and she give slive birth to about 20 pups after a 5 to 6 month pregnancy. Young cat sharks are spotted, and only grow into their brown coloring when they reach sexual maturity, at around 10 to 20 years old.

Conservation status: The IUCN lists the Nurse Shark as Vunerable. Historically they have been captured for their fins, skin and meat, as well as for the aquarium trade. They are also caught as by-catch in fishing nets. However, the species has several protected habitats along the North and Central American Atlantic coast and is currently being evaluated to better protect its migratory pathways.

Photos

Tchami

Gary Rinaldi

Kent Miller

[dailyelasmobranch]

Nurse shark - Ginglymostoma cirratum

Native to the coastal tropical and subtropical waters of the Atlantic and the eastern Pacific, the nurse shark is a nocturnal species that spends the day resting under ledges or in reef crevices. Though it can be observed resting in close groups of up to 40 individuals, sometimes piled on top of each other, at night the nurse shark is a solitary hunter that seeks out stingrays, fish, molluscs, and crustaceans along the sea floor. It is also known to graze on algae and corals. The mouth is small but the nurse shark's pharynx is large and bellows-like, enabling it to suck in prey at a high speed. Adults can achieve a length of about 14ft, making it the largest in the Ginglymostomatidae (nurse shark) family. Despite its wide distribution and apparent abundance in certain areas, there is not enough data to determine its overall status at present, though it is believed to be vulnerable to human impact (including pollution and disturbance from tourism) and some fisheries.