Lemon Shark (Mangroves Areas as Nursery Sites) скачать в хорошем качестве

Lemon Shark (Mangroves Areas as Nursery Sites)

The lemon shark (Negaprion brevirostris) is a species of shark from the family Carcharhinidae. The Lemon shark lives in the tropical and subtropical waters of the coastal areas of the Atlantic and Pacific Oceans. Lemon sharks are named for the yellow-brown skin that helps them camouflage in the sandy, tropical waters they inhabit. They stay in moderately shallow water, normally going no deeper than 80 meters. They are often found in shallow waters near coasts and islands, by coral reefs, mangroves, bays, and sometimes even river mouths. The lemon shark commonly attains a length of 2.4 to 3.1 m and a weight up to 90 kg by adulthood. They are slightly smaller in size than the whale shark, which is considered to be the biggest of the shark species. Lemon sharks have a flattened head along with a short broad snout. They have two equal-sized dorsal fins and their yellow coloring serves as a camouflage when they are swimming on the seafloor filled with sand. Like any other species of shark, have electroreceptors concentrated in their heads, called the ampullae of Lorenzini. These receptors detect electrical pulses emitted by potential prey and allow these nocturnal feeders to sense their prey in the dark. The skin of female lemon sharks is almost three times thicker than that of males. The lemon shark is viviparous, meaning it gives birth to live young rather than eggs. Embryos develop inside the mother for up to 12 months until the female seeks shelter in a shallow nursery during spring or summer to give birth. A litter of lemon sharks may be as large as 17 pups. Pups remain in the nursery for several years, sheltered from larger predators, and feed on nutrients from nearby mangroves. The mangrove areas that lemon sharks inhabit are often referred to as their nursery sites. Nursery grounds can be defined generally as habitats that enhance the growth and survival of juveniles. A nursery site is best defined as the most common area sharks are encountered, the location sharks tend to remain after birth or frequently return to, and the habitat used by shark groups repeatedly for several years. Lemon sharks display natal philopatry, whereby a mother will return to where she was born to have her own pups. One theory is that lemon sharks select mangrove habitats due to the abundance of prey that resides there, while another theory posits that mangroves provide a safe haven from adult lemon sharks that occasionally feed on juvenile sharks and are unable to enter the shallow waters. Lemon sharks reach sexual maturity at around 6 years of age and may live for up to 27 years. Female sharks deposit their pups in shallow, coastal waters, and they live in these reef and mangrove nurseries for up to four years. As adults, they move to deeper waters of up to about 90 meters deep. 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. 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 depending on the amount of food consumed at a single time. Intraspecific predation, or cannibalism, of juvenile lemon sharks by larger conspecifics, has also been documented. They also tend to prefer prey when it is more abundant and available. Lemon sharks feed selectively on species that are slower and more easily captured by using a stalking technique. Lemon sharks are known to be social creatures, who move in groups or loose aggregations. They form groups based on similar size or sex. Living in groups helps to enhance their communication further and intensifies courtship and predatory behavior. Since Lemon sharks can blend into their surroundings so well. they are able to do fairly well in captivity. That is not usually the case with species of sharks. Lemon sharks do not represent a large threat to humans. The International Shark Attack File lists 10 unprovoked lemon shark bites, none of which were fatal. Lemon sharks are listed as a 'near threatened' species by the International Union for Conservation of Nature. The destruction of the mangrove, which is one of their primary habitats, and the practice of 'shark finning, a practice where their dorsal fins are used to make fin soup and eaten by several communities, have decreased their number form the world gradually. They have also been killed for their meat which is considered a delicacy in several communities and their skin which is used for leather by humans. #Nature #Mangrove # #NurseryGrounds