AY Honors/Species Account/Negaprion brevirostris

Template:Taxobox The lemon shark, Negaprion brevirostris, is a shark in the family Carcharhinidae, that can grow to Template:Convert long. It is known as the lemon shark because, at certain depths, light interacting with the local seawater can give this shark a tanned and yellow pitted appearance, much like the surface of a lemon.

Description

This stocky, powerful shark is named for its pale yellow-brown to grey skin, which lacks any distinctive markings. This provides perfect camouflage when swimming over the sandy seafloor in its coastal habitat. It has a flattened head with a short, broad snout, and the second dorsal fin is almost as large as the first.

Distribution and habitat

The lemon shark is found mainly along the subtropical and tropical parts of the Atlantic and Pacific coasts of North and South America, and around Pacific islands. The longest lemon shark recorded was Template:Convert long, but they are usually Template:Convert. They like tropical water, and like to stay at moderate depths. They are often accompanied by remoras.

Reproduction

Lemon sharks are viviparous, females giving birth to between 4 and 17 young every other year in warm and shallow lagoons. The young have to fend for themselves from birth, and remain in shallow water near mangroves until they grow larger. With increasing size they venture further away from their birthplace. At maturity, at a size of 1.5–2 m and an age of 12–15 years, they leave shallow water and move into deeper waters offshore. However, little is known of this life stage. Maximum recorded length and weight is 340 cm and 183 kg.

Recent work in genetics by Kevin Feldheim and Samuel Gruber may suggest that adult sharks travel hundreds of kilometers to mate. Another possibility is that populations far apart may have been separated in recent times. Further research in this area in needed for an understanding of the lemon shark's breeding behavior and ecology.

Importance to humans

Lemon shark in Turks and Caicos Islands.

Lemon sharks are a popular choice for study by scientists as they survive well in captivity, unlike many other species such as the great white, which die in captivity because of food refusal. The species is the best known of all sharks in terms of behavior and ecology, mainly because of the work of Samuel Gruber at the University of Miami, who has been studying the lemon shark both in the field and in the laboratory since 1967. The population around the Bimini Islands in the western Bahamas, where Gruber's Bimini Biological Field Station is situated, is probably the best known of all shark populations. As of 2007, this population is experiencing a severe decline and may disappear altogether as a result of destruction of the mangroves for construction of a golf resort. There have been 22 known lemon shark attacks since 1580, but no deaths.

Electroreceptors

All sharks have electroreceptors concentrated in their heads, called the ampullae of Lorenzini. These receptors detect electrical pulses emitted by potential prey. Lemon sharks are bottom dwellers. They have very poor eyesight and cannot see well to find their food, but are equipped with extremely sensitive and accurate magnetic sensors in the nose.

See also

• List of sharks

References

• Template:ITIS
• Template:FishBase species
• Washington Post, 2005, Aug. 22nd: "Scientists Fear Oceans on the Cusp Of a Wave of Marine Extinctions"

External links

• Template:ARKive
• Lemon shark facts and pictures