While adult lemon sharks may occasionally eat juveniles, there are no known predators of adult lemon sharks.
Known Predators:
The coloration of lemon sharks varies from dark olive to yellowish brown dorsally, with a lighter yellow underside; they have no conspicuous markings. These sharks are large and stocky, with blunt snouts that are shorter than the width of their mouths. The bottom teeth are triangular and narrow with smooth-edged cusps, while the upper teeth are more broad and have smooth cusps and serrated bases. Teeth become more oblique as they near the corners of the mouth. They have two dorsal fins, with the posterior fin being shorter than the anterior, and paired pectoral and pelvic fins. This species is sexually dimorphic, with females being larger than males (averaging 240 cm vs 225 cm, respectively, though larger individuals have been found).
Range mass: 183.7 (high) kg.
Range length: 240 to 368 cm.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
The longest recorded lifespan for the lemon shark in captivity is 25 years. Using size and growth rate information, individuals caught in the wild have been estimated at over 30 years old.
Range lifespan
Status: wild: 30 (high) years.
Range lifespan
Status: captivity: 25 (high) years.
Lemon shark are most commonly found in shallow ocean waters (to depths of 90 m), in habitats including mangroves, coral reefs and enclosed bays. They have also been known to congregate around docks. These sharks may be found in brackish and freshwater as well, most typically in river mouths and sounds, though they do not typically venture deep into these areas. They can be found in the open ocean during migrations. Lemon sharks can adapt to low oxygen and shallow water environments and may be found resting on ocean bottoms.
Range depth: 0 to 90 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: pelagic ; benthic ; reef ; coastal ; brackish water
Lemon sharks inhabit the Nearctic region of the Atlantic Ocean, from the coast of New Jersey, USA to southern Brazil, the Caribbean, and the Gulf of Mexico. There have also been sightings of lemon sharks along the coasts of Senegal and the Ivory Coast in Africa. This species is also found in the eastern Pacific Ocean, from Baja California to Ecuador. Lemon sharks are migratory and are found in oceanic waters during migration, but tend to be found in coastal areas otherwise. Efforts are underway to learn more specifics of lemon shark migration through tagging and tracking.
Biogeographic Regions: nearctic (Native ); neotropical (Native ); atlantic ocean (Native ); pacific ocean (Native )
Lemon sharks use a number of sensory channels. Their retinas have specialized horizontal bands known as "visual streaks" that are extremely rich in cones, which discern color and visual detail. Their vision is very important in prey capture, as evidenced by an experiment conducted at the Lerner Marine Laboratory, which found that temporarily blinded lemon sharks were not able to detect a 113 kg chunk of blue marlin (Makaira mazara), while unimpaired lemons sharks found the blue marlin with ease. Lemon sharks do, however, have an acute sense of smell; another experiment at the same laboratory found that individuals of this species were able to detect one part of tuna juice in 25 million parts of sea water. As with all sharks, lemon sharks have ampullary receptors (Ampullae of Lorenzini) concentrated on their heads, which sense electric charges and serve to help them hone in on prey items. These sharks also have a homing sense, enabling females to return to the same areas each time they give birth and juveniles to return to safe nursery waters.
Communication Channels: visual ; tactile
Perception Channels: visual ; acoustic ; chemical ; electric
Although lemon sharks are classified as "Near-Threatened" by the International Union for Conservation of Nature (IUCN), there are no management plans currently in place for this species.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Following mating, female lemon sharks gestate developing young for 10-12 months, after which they give birth to a litter of 4-17 live pups. Young are typically 60-65 cm long at birth and these sharks grow throughout their lifetimes, at an average rate of 0.54 cm/year.
Development - Life Cycle: indeterminate growth
This animal poses only a minor threat to humans; there are only 10 recorded unprovoked lemon shark attacks (none fatal) on record in the International Shark Attack File.
Negative Impacts: injures humans (bites or stings)
Lemon shark meat has been marketed fresh, salted or frozen and their fins, in particular, are prized among Asian cultures for use in shark-fin soup. Liver oil from lemon sharks has been used for its vitamin content and its hide has been used as leather.
Positive Impacts: food ; body parts are source of valuable material; source of medicine or drug ; research and education
Lemon sharks are hosts to a variety of ectoparasitic copepod species, as well as several endoparasitic fluke and tapeworm species. It has also been found with attached remoras (Echeneis naucrates), or sharksuckers, which feed on scraps from feeding lemon sharks and can also help to keep infestations of dermal parasites in check.
Mutualist Species:
Commensal/Parasitic Species:
Lemon sharks feed on molluscs, crustaceans, and bony fish. Some examples of prey items include cowfish (Acanthostracion quadricornis), flathead mullets (Mugil cephalus), spot-fin porcupinefish (Diodon holocanthus), Atlantic guitarfish (Rhinobatos lentiginosus), spotted eagle rays (Aetobatus narinari), brown crabs (Cancer pagurus), red swamp crayfish (Procambarus clarkii), and southern stingrays (Dasyatis americana). Juveniles are known to feed on giant tiger prawns (Penaeus monodon) and shore crabs (Carcinus maenas).
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
Mating occurs during the spring months, and is followed by a period of gestation for 10-12 months. It is likely that females store sperm from multiple mates to allow sperm competition, as a recent study showed that many lemon shark litters exhibit multiple paternity, indicating that this species is polyandrous. Mating is generally accomplished by a male biting a female on the pectoral fin and inserting his clasper (sexual organ) into her cloaca; recently mated females exhibit "mating wounds" from this behavior.
Mating System: polyandrous
Lemon sharks breed seasonally, typically during the spring and summer months. These sharks are viviparous and give birth to litters of 4-17 pups. Gestation period is 10-12 months and there is some evidence that, after producing a litter, females take a year off before mating again. Each time they give birth, female lemon sharks return to the same nursery areas. Juveniles remain in shallow waters of the nursery area, likely to avoid predators and have easy access to shore-line prey, for 2-3 years. They do not typically leave these safe areas until they have reached at least 90 cm in length and are less vulnerable. There is not much known beyond this regarding how and when juveniles leave for open waters and adult habitats, although there is evidence that they remain nearby their nursery areas for a number of years.
Breeding interval: Lemon sharks breed once yearly.
Breeding season: Lemon sharks breed during spring and summer months.
Range number of offspring: 4 to 17.
Range gestation period: 10 to 12 months.
Range age at sexual or reproductive maturity (female): 6 to 7 years.
Range age at sexual or reproductive maturity (male): 6 to 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous ; sperm-storing
Following mating, there is parental involvement by male lemon sharks. Females gestate young for 10-12 months.
Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female)
The lemon shark (Negaprion brevirostris) is a species of shark from the family Carcharhinidae and is classified as a Vulnerable species by the International Union for the Conservation of Nature.[3] Lemon sharks can grow to 3.4 metres (11 ft) in length. They are often found in shallow subtropical waters and are known to inhabit and return to specific nursery sites for breeding. Often feeding at night, these sharks use electroreceptors to find their main source of prey: fish. Lemon sharks enjoy the many benefits of group living such as enhanced communication, courtship, predatory behavior, and protection. This species of shark gives birth to live young, and the females are polyandrous and have a biennial reproductive cycle. Lemon sharks are not thought to be a large threat to humans; there have been 10 recorded bites, none of which were life-threatening. The lemon shark's life span is unknown, but the average shark is 25 to 30 years old.[4]
The lemon shark was first named and described in 1868 by Felipe Poey.[5] He originally named it Hypoprion brevirostris, but later renamed it Negaprion brevirostris.[5] The lemon shark has also appeared in literature as Negaprion fronto and Carcharias fronto (Jordan and Gilbert, 1882), Carcharias brevirostris (Gunther, 1870), and Carcharhinus brevirostris (Henshall, 1891).[5]
The shark's yellow colouring serves as an excellent camouflage when swimming over the sandy seafloor in its coastal habitat.[6] The lemon shark commonly attains a length of 2.4 to 3.1 m (7.9 to 10.2 ft) and a weight up to 90 kg (200 lb) by adulthood, although sexual maturity is attained at 2.24 m (7.3 ft) in males and 2.4 m (7.9 ft) in females.[7] The maximum recorded length and weight is 3.43 m (11.3 ft) and 183.7 kg (405 lb), respectively.[8] It has a flattened head with a short, broad snout, and the second dorsal fin is almost as large as the first. Like all cartilaginous fish, lemon sharks have electroreceptors concentrated in their heads, known as the ampullae of Lorenzini.[9] These receptors detect electrical pulses emitted by potential prey and allow these nocturnal feeders to sense their prey in the dark.[9] Note that Lemon shark are often confused with Bull shark, Lemon shark have roughly equal first and second dorsal fins where Bull sharks have uneven size.[10]
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.[11] In addition, lemon sharks have been found in the eastern Pacific, from southern Baja California to Ecuador and in Cape Verde in Sal Island.[11] This species of shark often occupies the subtropical shallow waters of coral reefs, mangroves, enclosed bays, and river mouths; however, lemon sharks have also been found in the open ocean down to depths of 92 meters (301 feet.)[12] Although lemon sharks do swim up rivers, they never seem to travel very far into fresh water. They are found in open water primarily during migrations, and tend to stay along the continental and insular shelves for most of their lives.[2]
Information about activity patterns and the use of space is important in understanding a species’ behavioral ecology.[13] Animals often make decisions about habitat use by evaluating their environment's abiotic conditions that serve as valuable indicators of good foraging sites or predator-safe locations.[14] Lemon sharks select habitats in warm and shallow water with a rocky or sandy bottom.[13]
The environmental temperature influences an individual's body temperature, which ultimately affects physiological processes such as growth and metabolism.[14] Lemon sharks, therefore, select warm-water habitats to maintain optimal metabolic levels. They are believed to avoid areas with thick sea grasses because they make finding prey more difficult.[14] Lemon sharks tend to live in or near shallow-water mangroves, which are often the nursery areas of several species of fish. The data gathered about the characteristics of shark nursery areas is mostly based on coastal species, this is due to their occurrence in bays, estuaries, river deltas, and shallow coastal waters. [15] 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.[16] Ontogenetic niche shifts, or changes in an animal's niche breadth or position, to deeper waters are known to occur in relation to a lemon shark's size. These changes occur due to the dramatic decrease in the risk of predation as body size increases.[14] Habitat selection clearly depends on a variety of biological and environmental variables.
The mangrove areas that lemon sharks inhabit are often referred to as their nursery sites. A nursery site is best defined as the most common area sharks are encountered, the location sharks tend to remain at after birth or frequently return to, and the habitat used by shark groups repeatedly for several years.[17] The nursery ground concept has been known and studied for at least a century. In addition, fossil evidence from 320 million years ago suggests the use of shallow, coastal areas as pupping grounds is primitive.[17]
Lemon sharks have proven to be an ideal model species to challenge the belief that all sharks are asynchronous opportunistic predators due to their tendency to use nursery areas for an extended period of time.[18] Lemon shark feeding behaviors are easy to determine because their well-defined home ranges are conducive to accurate calculations of both the amount and types of prey in the environment and diet of a lemon shark.
Lemon sharks feed at night and are mainly piscivorous; however, they have been known to feed on crustaceans and benthic organisms.[19] Intraspecific predation, or cannibalism, of juvenile lemon sharks by larger conspecifics has also been documented.[14] Rather than feeding randomly, lemon sharks display a high degree of preference for certain species and size of prey when environmental conditions are favorable.[20] They also tend to prefer a 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.[21] For example, parrotfish and mojarras are common prey in the Bahamas because they use camouflage rather than an escape response and are vulnerable due to their stationary foraging behavior. Lemon sharks feed on prey that are intermediate in size compared to other available prey.[19] This tendency can be explained by the tradeoff between the probability of capture and the profitability when it comes to prey size. The general trend in the foraging behavior of lemon sharks conforms to the optimal foraging theory, which suggests a positive relationship between prey selectivity and availability.[18]
Rather than rolling on their sides to rip off chunks of prey, lemon sharks approach their victim with speed only to brake suddenly using their pectoral fins upon contact.[19] The animal then jabs forward multiple times until it has a good grasp of its prey in its jaw and proceeds to shake its head from side to side until it tears off a chunk of flesh. A feeding frenzy, or large swarm of other sharks, then forms as the individuals sense the blood and bodily fluids released from the prey.[19] Sounds of struggling prey also attract groups of sharks, suggesting they use sound detection for predation.[21] Group feeding behavior such as pack hunting or communal scavenging was observed in a study in which pieces of the same stingray were found in the stomachs of several lemon shark individuals that were caught and examined.
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Many species of sharks, including the lemon shark, are known to actively prefer to be social and live in groups or loose aggregations.[22] A few benefits of group living are enhanced communication, courtship, predatory behavior, and protection. Group living and a preference for social interaction is thought to be important for the survival and success of juvenile lemon sharks.[22] Group living, though, comes with its costs. A few include increased risk of disease, ease of parasite transmission, and competition for resources.[23]
Lemon sharks are found in groups based on similar size. Passive sorting mechanisms such as its ontogenetic habitat shift have been postulated to contribute to the formation of groups organized based on size or sex.[24] One exception to this behavior is that sharks up to 1 year old show no preference for groups of matched or unmatched size.[22] One hypothesis for this finding is that it is beneficial for the small young lemon sharks to associate with the larger individuals because they have an easier time gathering information about the habitat regarding elements such as predators and local prey.[22] Lemon shark groups form due to an active desire to be social rather than a simple attraction to the same limited resources such as the mangrove habitat and prey associated with such a habitat.[24]
Many studies have related brain size with complex social behaviors in mammals and birds.[24] The brain of a lemon shark, being comparable in relative mass to that of a mammal or bird, suggests they have the ability to learn from social interactions, cooperate with other individuals, and have the potential to establish dominance hierarchies and stable social bonds.[22]
Lemon sharks congregate for reproduction at special mating grounds.[25] Females give birth to their young in shallow nursery waters to which they are philopatric. Lemon shark young are known as pups and they tend to remain in the nursery area for several years before venturing into deeper waters.[26] Lemon sharks are viviparous, meaning that the mother directly transfers nutrients to her young via a yolk-sac placenta and the young are born alive.[25] Fertilization is internal and occurs after a male lemon shark holds a female, bites her, and inserts his clasper into her cloaca.[25] Female lemon sharks are polyandrous and sperm competition occurs due to their ability to store sperm in an oviducal gland for several months.[25] Several studies suggest that polyandry in female lemon sharks has adapted out of convenience, rather than indirect genetic benefits to offspring.[27] This type of polyandry is termed as convenience polyandry because females are believed to mate multiple times to avoid harassment by males.[27] Females have a biennial reproductive cycle, requiring a year for gestation and another year for oogenesis and vitellogenesis after parturition. Lemon sharks reach sexual maturity around 12–16 years of age and have low fecundity. Males tend to mature earlier than females.[28] The maximum number of pups recorded in a litter is 18.[25]
This species of shark is best known in its behavior and ecology, mainly due to the work of Samuel Gruber at the University of Miami, who studied the lemon shark both in the field and in the laboratory from 1967.[13] 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.[13]
The lemon shark is targeted by commercial and recreational fishers along the U.S. Atlantic Ocean, Caribbean, and in the eastern Pacific Ocean due to its prized meat, fins, and skin. Lemon shark skin may be used for leather and its meat can be consumed and is believed to be a delicacy in many cultures.[2] Concern exists that over-fishing has led the lemon shark populations in the western north Atlantic and eastern Pacific Ocean to decline.[5] It is considered vulnerable.[6]
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.[5]
This article incorporates text from the ARKive fact-file "Lemon shark" under the Creative Commons Attribution-ShareAlike 3.0 Unported License and the GFDL.
The lemon shark (Negaprion brevirostris) is a species of shark from the family Carcharhinidae and is classified as a Vulnerable species by the International Union for the Conservation of Nature. Lemon sharks can grow to 3.4 metres (11 ft) in length. They are often found in shallow subtropical waters and are known to inhabit and return to specific nursery sites for breeding. Often feeding at night, these sharks use electroreceptors to find their main source of prey: fish. Lemon sharks enjoy the many benefits of group living such as enhanced communication, courtship, predatory behavior, and protection. This species of shark gives birth to live young, and the females are polyandrous and have a biennial reproductive cycle. Lemon sharks are not thought to be a large threat to humans; there have been 10 recorded bites, none of which were life-threatening. The lemon shark's life span is unknown, but the average shark is 25 to 30 years old.
