Lemon shark

Lemon shark
A Lemon shark swimming with Remoras in the Bahamas
Conservation status
Near Threatened  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Carcharhiniformes
Family:	Carcharhinidae
Genus:	Negaprion
Species:	N.brevirostris
Range of the Lemon shark
Synonyms
Carcharias fronto Jordan & Gilbert, 1882 Hypoprion brevirostris Poey, 1868

The Lemon shark is a shark that gets its name from its deep yellow back. Its belly is off-white. Lemon sharks are usually eight to ten feet long. They have long, sharp teeth for catching slippery fish. Lemon sharks are common on the southeast coast of the United States of America.^[1] The jaws of a Lemon Shark are wide and are not

easily opened repeativley. The jaws are opened by muscle activity in the dorsal

and ventral preorbitalis. (midventral surface of the chondrocranium) It's function is to allow the shark to open its mouth

to eat or consume its prey and use it's teeth properly in order to eat.

Description

The Lemon shark gets its name from the fact that it is yellow in colour. The underside is usually white or a lighter yellowish colour. Besides yellow, the Lemon shark is also brown and olive grey in colour. The Lemon shark is stocky, blunt-nosed, and has two dorsal fins of similar size and shape. The first dorsal fin is low and positioned at the back of the pectoral fins, and the second dorsal is of similar shape and size and positioned at the front of the anal fin. The pelvic fin weakly concave (curving inwards) rear margins, and the pectoral fin's outer margin is slightly convex (curving outwards), and both fins are weakly falcate. The snout is round and shorter than the width of the mouth. There is no mid-dorsal ridge present on this species. The upper teeth are narrow and broad with triangular smooth-edged cusps and finely serrated bases. These teeth get more oblique as they get closer to the corner of the mouth. The lower teeth are narrow and triangular with smooth-edged cusps. Lemon shark scales are large and overlapping with 3 to 5 ridges. The middle ridge is high, sharp and separated by deep furrows, and the back margins are opposite the primary ridges. The basal plates and pedicels are broad. Lemon sharks usually range between the lengths of 2.4 to 3 metres (7.9 to 9.8 ft), and have a growth rate of 0.21 inches per year (0.54 cm per year). The maximum length that can be reached by this species is between 3.2–3.4 m (10–11 ft). Pups are between 24-26 inches (60-65 cm) at birth. ^[2]

Reproduction

The Lemon shark is viviparous, meaning that they give live birth. After a gestation period of 10 to 12 months, pregnant females enter shallow nursery areas in spring and summer to give birth to litters of 4 to 17 pups. The pups have a very slow growth rate and remain within nursery grounds for quite a long time, where they are in less danger from predators. The mangroves that the young mainly inhabit are highly productive waters, creating an excellent area for feeding, but also an area of very low oxygen content. However, the Lemon shark has many adaptations that increase oxygen uptake, such as blood with an unusually high affinity for oxygen. As they grow, their range increases dramatically, from 6–8 kilometres (3.7–5.0 mi) up to around 300 km (190 mi). Maturity is reached at about 6 and a half years of age, and it is believed that the Lemon shark lives for up to 27 years.^[3]

Behaviour

When it comes to hunting, the Lemon shark is known to be very patient. They are able to use their yellow coloring to help them successfully hide in their natural habitat. They are often found swimming along the sand of the bottom of the water so they blend in easily. This makes it easy to hide from predators and also to be able to find prey. It is believed that this shark has a special set up with the retina. This enables them to be able to see very clearly even in the murky depths under the water. The Lemon Shark can be aggressive to humans, and is known to have a powerful bite. Most of the attacks that have been noted were provoked, but not all. Since Lemon sharks can blend into their surroundings so well, it is easy for someone to accidentally disrupt the shark. What is encouraging about the Lemon Shark is that they are able to do fairly well in captivity. That is not usually the case with species of sharks. Still, many experts worry that they won’t copy all they do in the wild in captivity so they don’t usually rely on such details and observations as facts if they can’t also be confirmed in the wild. They are very social, and they develop a hierarchy based on gender and size that is very complex. The Lemon Shark is gentle in nature and doesn’t seem to be aggressive towards people, including divers. They have been known to bite humans but it is believed this is due to being provoked. They aren’t seen as a major threat to sharing the waters with humans. ^[4]

Feeding

The Lemon shark's diet consists mainly of bony fish and crustaceans. Catfish, mullet, jacks, croakers, porcupine fish, cowfish, guitarfish, stingrays, eagle rays, crabs and crayfish make up most of the Lemon shark's diet. Also, this species will eat sea birds and smaller sharks. Lemon sharks will eat until full with the rate of digestion dependent on the amount of food consumed at a single time. ^[2]

Habitat

The Lemon shark lives in the tropical and subtropical waters of the coastal areas of the Atlantic and Pacific Oceans. They stay in moderately shallow water, normally going no deeper than 80 meters (roughly 260 feet). They are often found in shallow waters near coasts and islands, by coral reefs, mangroves, bays, and sometimes even river mouths. ^[5]

Human interaction

These sharks represent a small threat to humans. According to the International Shark Attack File, there have been only 10 unprovoked attacks by Lemon sharks, all occurring in Florida and the Caribbean. There have been no fatal attacks from this species. The Lemon shark does inhabit coastal waters which swimmers, surfers and divers commonly swim in. The low number of attacks by this species shows that it is a small threat to humans. The Lemon shark is targeted by commercial and recreational fishermen along the U.S, Atlantic Ocean, Caribbean, and in the eastern Pacific Ocean. The US bottom longline fishery commonly targets this species and it is also caught as by-catch in both pelagic and gillnet fisheries. Their fins are highly prized and are exported to Asia for shark fin soup. Their skin may be used for leather and their meat is eaten by humans. There is some concern that populations in the western north Atlantic and eastern Pacific Ocean are in danger due to over-fishing. ^[2]

References

1. Cole, Joanne; Bruce Degen (2001). Magic School Bus, Shark Escape. United States of America: Scholastic Inc. p. 83. ISBN 0-439-31432-1.
2. "FLMNH Ichthyology Department: Lemon Shark". flmnh.ufl.edu. Archived from the original on 14 November 2013. Retrieved 20 June 2013.
3. "Facts about Lemon Shark (Negaprion brevirostris)-Encyclopedia of Life". eol.org. Archived from the original on 6 January 2014. Retrieved 20 June 2013.
4. "Lemon Shark-Animal Facts and Information". bioexpedition.com. 13 June 2012. Retrieved 20 June 2013.
5. "Lemon Shark Facts |Shark Breed Info |Types Of Sharks". the-shark-side-of-life.com. Archived from the original on 19 July 2013. Retrieved 20 June 2013.