The Ginglymostomatidae are a

cosmopolitan Cosmopolitan may refer to: Food and drink * Cosmopolitan (cocktail), also known as a "Cosmo" History * Rootless cosmopolitan, a Soviet derogatory epithet during Joseph Stalin's anti-Semitic campaign of 1949–1953 Hotels and resorts * Cosmopoli ...

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

carpet shark Carpet sharks are sharks classified in the order Orectolobiformes . Sometimes the common name "carpet shark" (named so because many species resemble ornately patterned carpets) is used interchangeably with "wobbegong", which is the common name o ...

s known as nurse sharks, containing four species in three

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...

. Common in shallow, tropical and subtropical waters, these sharks are sluggish and docile bottom-dwellers."Ginglymostomatidae Gill, 1862"
World Register of Marine Species. Retrieved 2014-2-2. Nurse sharks typically attack humans only if directly threatened. The name nurse shark is thought to be a corruption of ''nusse'', a name which once referred to the

catshark Catsharks are ground sharks of the family Scyliorhinidae. They are the largest family of sharks with around 160 species placed in 17 genera. Although they are generally known as catsharks, some species can also be called dogfish due to previous n ...

s of the family Scyliorhinidae. The nurse shark family name, Ginglymostomatidae, derives from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words ''ginglymos'' () meaning "hinge" and ''stoma'' () meaning "mouth".

Description

The largest species, called simply the

nurse shark The nurse shark (''Ginglymostoma cirratum'') is an elasmobranch fish in the family Ginglymostomatidae. The conservation status of the nurse shark is globally assessed as Vulnerable in the IUCN List of Threatened Species. They are considered t ...

''Ginglymostoma cirratum'', may reach a length of ; the

tawny nurse shark The tawny nurse shark (''Nebrius ferrugineus'') is a species of carpet shark in the family Ginglymostomatidae, and the only extant member of the genus '' Nebrius''. It is found widely along coastlines in the Indo-Pacific, preferring reefs, s ...

''Nebrius ferrugineus'' is somewhat smaller at , and the

short-tail nurse shark The short-tail nurse shark (''Pseudoginglymostoma brevicaudatum'') is a nurse shark in the family Ginglymostomatidae, the only member of the genus ''Pseudoginglymostoma''. It is found in the tropical western Indian Ocean between latitudes 0° a ...

''Pseudoginglymostoma brevicaudatum'' is by far the smallest at just in length. The first of the three species may reach a weight of 110 kg. Yellowish to dark brown in colour, nurse sharks have muscular

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s, two spineless

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

s (the second of which is smaller) in line with the

pelvic The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

and

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

s, and a tail exceeding one quarter the shark's body length. The mouth of nurse sharks is most distinctive; it is far ahead of the eyes and before the snout (subterminal), an indication of the bottom-dwelling (benthic) nature of these sharks. Also present on the lower jaw are two fleshy

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some ...

, chemosensory organs which help the nurse sharks find prey hidden in the sediments. Behind each eye is a very small, circular opening called a

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

, part of the shark's respiratory system. The serrated teeth are fan-shaped and independent; like other sharks, the teeth are continually replaced throughout the animal's life.

Habits

Nurse sharks are nocturnal animals, spending the day in large inactive groups of up to 40 individuals. Hidden under submerged ledges or in crevices within the

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

, the nurse sharks seem to prefer specific haunts and will return to them every day. By night, the sharks are largely solitary; they spend most of their time searching through the bottom sediments in search of food. Their diet consists primarily of

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...

s, and other

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

, particularly

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae ( ...

s. Nurse sharks are thought to take advantage of dormant fish which would otherwise be too fast for the sharks to catch; although their small mouths limit the size of prey items, the sharks' large throat cavities are used as a sort of bellows valve. In this way, nurse sharks are able to suck in their prey. Nurse sharks are also known to graze

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

and

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

Reproduction

The mating season runs from late June to the end of July. All nurse sharks are aplacental

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

, meaning the eggs develop and hatch within the body of the female, where the hatchlings develop further until live birth occurs. The

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pregna ...

period is six months, with a typical litter of 30–40 pups. The mating cycle is biennial, as it takes 18 months for the female's ovaries to produce another batch of eggs. The young nurse sharks are born fully developed at about 30 cm long in ''Ginglymostoma cirratum''. They possess a spotted coloration that fades with age.

Genera and species

* Genus ''

Ginglymostoma ''Ginglymostoma'' is a genus of shark in the family Ginglymostomatidae. There are two members in the genus. Members of this genus eat small fish and crustaceans, and are commonly quite lethargic unless provoked. Members of this genus have the abi ...

'' J. P. Müller &

Henle Henle can refer to: * Friedrich Gustav Jakob Henle, a German physician, pathologist and anatomist (1809–1885) ** Loop of Henle in the kidney, named after Henle *Fritz Henle, a photographer, known as "Mr. Rollei" for his use of the 2.25" square for ...

, 1837 ** '' Ginglymostoma cirratum'' Bonnaterre, 1788 (nurse shark) ** '' Ginglymostoma unami'' Del-Moral-Flores, Ramírez-Antonio, Angulo & Pérez-Ponce de León, 2015 * Genus ''

Nebrius ''Nebrius'' is a genus of carpet sharks in the family Ginglymostomatidae. It contains a single extant species, the tawny nurse shark (''Nebrius ferrugineus''), as well as a number of extinct species dating back to the Early Paleocene.Bourdon, ...

'' Rüppell, 1837 ** ''

Nebrius ferrugineus The tawny nurse shark (''Nebrius ferrugineus'') is a species of carpet shark in the family Ginglymostomatidae, and the only extant member of the genus ''Nebrius''. It is found widely along coastlines in the Indo-Pacific, preferring reefs, sa ...

Lesson A lesson or class is a structured period of time where learning is intended to occur. It involves one or more students (also called pupils or learners in some circumstances) being taught by a teacher or instructor. A lesson may be either one ...

, 1831 (tawny nurse shark) * Genus ''

Pseudoginglymostoma The short-tail nurse shark (''Pseudoginglymostoma brevicaudatum'') is a nurse shark in the family Ginglymostomatidae, the only member of the genus ''Pseudoginglymostoma''. It is found in the tropical western Indian Ocean between latitudes 0° a ...

'' Dingerkus, 1986 ** '' Pseudoginglymostoma brevicaudatum'' Günther, 1867 (short-tail nurse shark)

References

External links