Draft:Nurse Sharks

This discussion topic submitted by Sarah Rikas at 3:41 pm on 8/1/99. Additions were last made on Wednesday, May 7, 2014.

I had watched a show on the Discovery Channel which contained information on these interesting creatures. I thought it would be appropriate to talk about them because they inhabit the areas which this course is designed around. The following is my final outline:
I. Classification
Quatiniformes have no anal fin and their bodies are flattened with a raylike mouth terminal.
Pristiophoriformes have no anal fin and their bodies are not raylike. They have a mouth ventrical and a sawlike, elongated snout.
Squaliformes have no anal fin and their bodies are not raylike. They have a mouth ventrical and a short snout which is not sawlike.
Hexanchiformes have an anal fin, 6 to 7 gill slits, and one dorsal fin.
Heterodontiformes have 5 gill slits, two dorsal finsand dorsal fin spines.
Carcharhiniformes have 5 gill slits, two dorsal fins, and no fin spines. Their mouth is behind the front of their eyes which have nictitating eyelids. They have a spiral intestinal valve.
Omniformes have 5 gill slits, two dorsal fins, and no fin spines. Their mouth is behind the front of their eyes which do not have nictitating eyelids. They have a ring intestinal valve.
Orectolobiformes have 5 gill slits, two dorsal fins, and no fin spines. Their mouth is well in front of the eyes.

II. Subject Focus
The sharks which I will be discussing are in the family Orectolobidae. Therefore, they have the attributes of an Orectolobiforme, as some of the class has gotten to see close up on Ginglymostoma cirratum. Also known as the nurse shark.

III. Coloration and Size
They have no conspicuous markings. They posess a basic brown coloration which varies from beige to shades of grey which fades gradually to a creamy white beneath. An observation was made that it would appear that those sharks which spend their days in caves are light in color, while those which remain in full sun exposure become darker.
This species is commonly between 6.5' and 10' in length. Some up to 14' have been found.

IV. Distribution, Biology and Habitat
These sharks can be found in the Eastern Pacific and Atlantic Oceans. They are the only species of carpet shark to inhabit the Atlantic.
Nurse sharks are nocturnal, bottom dwelling, inshore sharks found in lagoons and outer reefs. They lay motionless on the bottom with their head in a crevice or cavern. They are known to use the same crevice or cavern for long periods of time.

V. Feeding
This shark's diet consists mainly of whatever can be found. It usually includes sea urchins, crabs, octopus, squid, crustaceans, snails, bivalves and fish. They feed frequently and do so by placing their mouth in the closest possible proximity to a prey, opening the mouth with a vacuum force substantial enough to suck the prey from the safety of its refuge.

VI. Reproduction
The mating of a nurse shark is similar to the parallel swimming of the lemon shark, usually with the male slightly behind the female and at times including a third individual of unknown importance. They become sexually mature at 2.3m in length. They are live bearers whose usual brood counts between 20 and 30, foot long pups.

VII. Disposition
These animals are short sighted and easily frightened. They may attack swimmers, especially when provoked. They may become defensive, if not aggressive! Some divers may dispurse a repellant consisting of a dense cloud of nigrosine dye while in shark infested waters. Most sharks are deterred, but the nurse shark will enter the dense cloud and feed without hesitation while in it.
A bite by this species is brutal for, as is true of the entire family, they are reluctant to release the victim. On one occasion, a nurse shark had to be killed and the jaws pried open before the victim could be released.


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