The lemonshark is a stocky and powerful shark. A member of the family Carcharhinidae, lemon sharks can grow to 3.0 m in length. They are often found in shallow subtropical waters and are known to inhabit and return to specific nursery sites for breeding. Lemon sharks are found from New Jersey to southern Brazil in the tropical western Atlantic Ocean. They also live off the coast of west Africa in the southeastern Atlantic. Often feeding at night, these sharks use electroreceptors to find their main source of prey, fish. Lemon sharks use the many benefits of group living such as enhanced communication, courtship, predatory behavior, and protection. It is considered Near Threatened by the IUCN red list. Lemon sharks are not thought to be a large threat to humans.
“A young lemon shark loses an entire set of teeth, one at a time, every 7-8 days. The teeth are located in rows which rotate into use as needed. The first two rows are used in obtaining prey, the other rows rotate into place as they are needed. As teeth are lost, broken, or worn down, they are replaced by new teeth that rotate into place.” x
The popular view of sharks as wandering predators, roaming the seas like outcast swordsmen in an old samurai movie, will have to be adjusted, what with this month’s big news about lemon sharks (Negaprion brevirostris).
New study proves sharks are better mothers than previously thought - returning to where they were born (like seals and turtles) to give birth in the same safe havens.
Researchers say these sharks — so named for their yellowish skin — return not just to regional breeding grounds to give birth, but to their specific birthplaces, like salmon. As the mothers do, so do their offspring, for generation upon generation. This homing behavior, called “natal philopatry,” is also seen in seals and some sea turtles, but this is the first time it has been shown in sharks
A new study provides the first direct evidence that female sharks commonly return to their birthplaces to reproduce. This finding, from a study of lemon sharks (Negaprion brevirostris) in the Bahamas, took 17 years to document and suggests that local conservation efforts are crucial, even for a species whose range is hundreds of miles.
Lemon sharks are highly migratory, but scientists have suspected that adult females return to their birthplaces to give birth to their pups. This behavior, termed “natal philopatry,” has been demonstrated in other marine animals, such as salmon. But it is difficult to establish in most shark species because it requires that they be tracked for 10 or more years while they mature.
The scientists believe that natal philopatry explains their findings. Although six sharks may not seem like many, it is a meaningful number, because shark survival is generally low. The researchers also conclude that the sharks return to a very specific place to give birth.study,
The study suggest that effective conservation measures for highly migratory sharks should include protection of specific coastal habitat and restrictions on shark fishing at nursery sites at key times of the year.
Negaprion brevirostris (Carcharhinidae) is a powerful shark named as lemon shark for its pale yellow-brown to grey skin, which lacks any distinctive markings.
The lemon shark’s retina has a specialized horizontal band across the middle, which is disproportionately rich in cones that discern fine detail and color in well-illuminated conditions. This ‘visual streak’ is thought to provide the shark with a particularly clear view of its underwater world.
This shark is potentially dangerous to humans due to its large size (length up to 340 cm) and powerful bite, and though there have been some unprovoked attacks, many were the result of provocation from divers and swimmers.
Negaprion brevirostris occurs in the tropical western Atlantic, from New Jersey to southern Brazil; and in the north eastern Atlantic, off west Africa. It is also occasionally found in the eastern Pacific, from southern Baja California and the Gulf of California to Ecuador. Specimen shown was photographed in Bahamas.
The subtropical Atlantic lemon shark (Negaprion brevirostris) is named for its yellow-green colouring. They tend to be tricky and opportunistic – one of these two bit my camera moments after I took this picture. Photograph: John Bantin/John Bantin Source: The Guardian