Negaprion

Diversity

The genus Negaprion is one of 12 genera in the family Carcharhinidae , commonly known as requiem sharks. The genus contains two extant species: the lemon shark, Negaprion brevirostris , and the sicklefin lemon shark, Negaprion acutidens . The genus also includes one extinct species, Negaprion eurybathrodon . Species in this genus inhabit coastal water in the Atlantic, Pacific, and Indian Oceans and. They can measure between 150 and 300 cm and weigh up to 180 kg, and use their grayish yellow coloring to blend in to the sandy ocean floor (Morgan 2018). Lemon sharks are apex predators, but they are regularly hunted for their fins and are now listed as vulnerable on the IUCN Red List.

Geographic Range

Negaprion species inhabit tropical temperate regions around the world. The common lemon shark ( N. brevirostris ) is found in the nearctic and neotropical regions of the Atlantic Ocean, from the northern coast of the United States all the way to southern Brazil, including the Caribbean and the Gulf of Mexico. There is a relict population of N. brevirostris in the eastern Pacific along the coast of Central America (Morgan, 2018). In this population, there is evidence of allopatric speciation corresponding with the formation of the Panama land bridge (Schultz, 2008). The sicklefin lemon shark ( N. acutidens ) is found in the Indian Ocean along the eastern coast of Africa, around the Sinai Peninsula, and throughout the Indonesian Archipelago to Australia. g. Negaprion species were previously common throughout the tropical and subtropical Indo-West Pacific, but overfishing and habitat destruction has led to their disappearance from the coasts of India and Thailand.

• Biogeographic Regions
• nearctic nearctic
  • native native
• oriental oriental
  • native native
• ethiopian ethiopian
  • native native
• neotropical neotropical
  • native native
• australian australian
  • native native
• arctic ocean arctic ocean
  • native native
• indian ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Negaprion species inhabit coastal waters to depths no greater than 200m, though most individuals remain within 50m of the shoreline and often swim so close to the shore that their dorsal fins are exposed above the water. These sharks commonly inhabit mangroves, enclosed bays, and atolls, which also serve as popular nurseries (Filmalter, Dagorn, and Cowley, 2013). Juvenile lemons sharks have strong site attachment, establishing home ranges at birth and rarely traveling more than 20km away from their birthplace. Once mature, lemon sharks engage in migratory behavior, traveling along coastlines for thousands of kilometers.

• Habitat Regions
• tropical tropical
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic
• benthic benthic
• reef reef
• coastal coastal

Systematic and Taxonomic History

Lemon sharks belong to the class Chondrichthyes , or cartilaginous fishes, and the family Carcharhinidae , commonly known as requiem sharks. Other well-known members of this family include the tiger shark ( Galeocerdo cuvier ) and the blacktip reef shark ( Carcharhinus limbatus ).

Lemon sharks were first described as Hypoprion brevirostris in Poey 1868. The name was then changed the name to the current Negaprion brevirostris . This species also appears in literature as Carcharias fronto (Jordan and Gilbert, 1882), Carcharias brevirostris (Gunther 1870) and Carcharhinus brevirostris (Henshall 1891).

The genus Negaprion was described in Whitley 1940. There are 11 nominate species within the genus, but most of these can be synonymized with Carcharias acutidens , a species of sand tiger shark (Rüpell 1837). In 1944, Whitley mistakenly defined a new the genus Mystidens based on a set of teeth that were later found to belong to N. acutidens (Compagno, 2016). Similarly, the genus Hemigaleops was defined by Shultz in 1953 based on a specimen that later proved to be in the genus Negaprion , most likely N. acutidens .

Physical Description

Species in the genus Negaprion are characterized by their yellowish coloration, from which they derive the name lemon shark. This coloration can range from olive gray to lighter yellow-brown, with the lightest coloration on the undersides, and they lack conspicuous markings (Morgan 2018). Lemon sharks range from 150 to 300 cm in length, with two prominent dorsal fins - the posterior fin being only slightly shorter in length than the anterior fin. Lemon sharks also have paired pectoral and pelvic fins, small anal fins, and large caudal fins approximately one-fourth their total length (Yoshino 1981). They have broad heads with short snouts, and wide mouths with smooth-edged, single-cusped teeth. The genus is sexually dimorphic, with females smaller on average than males.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Development

Maturity is reached at 225cm for males and 235cm for females, or around 13 years of age. Lemon sharks measure between 55 and 60 centimeters at birth and grow at a rate of approximately four centimeters per month (Gruber, 1981). Some studies have recorded much faster growth rates. This is likely because captive individuals have four times faster growth rates than those in the wild, meaning that food availability is a limiting factor.

Reproduction

Information about shark breeding behavior is very limited, but it is known that they exhibit internal fertilization. Males have paired claspers used for sperm transfer by attaching to the female. The mating process involves males grasping onto females with their teeth, causing females to often exhibit lacerations during mating season (Feldheim, Gruber, and Ashley, 2002). Females can mate with several males in one mating season and also may store sperm from several males which results in multiple paternity of the litters.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Lemon sharks are viviparous, giving birth to between 4 and 17 live young in each litter. Females reach sexual maturity between 12 and 16 years of age and then follow a two-year reproductive cycle. Mating usually occurs in spring, with gestation lasting between 10 and 12 months. Females exhibit strong site fidelity for parturition, and their young maintain this strong attachment for several years after their birth.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• viviparous viviparous
• sperm-storing sperm-storing

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
• pre-hatching/birth
  • provisioning
  • protecting

Lifespan/Longevity

Lemon sharks can live up to 25 years in captivity. There have been no ongoing studies of lifespan in the wild. Negaprion species are estimated to live between 27 and 30 years based on growth rate information

Behavior

Lemon sharks are usually solitary but can found in groups of up to 20 individuals, often around fishing docks or protected atolls. These sharks are active throughout the day but are most active around dusk and dawn. Juvenile Negaprion species remain in the nursery areas until they are mature enough to begin their migrations. Little is known about the patterns or distances of these movements, but females will return to the same areas biannually to give birth to their young.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• migratory migratory
• solitary solitary

Communication and Perception

Lemon sharks use a number of sensory channels to communicate. Like all sharks, Negaprion species have specialized receptors on their snouts called Ampullae of Lorenzini, which can detect weak electrical fields. This adaptation allows them to detect the electrical currents given off by prey, as well as by salts in blood which allows them to locate potential prey. The Ampullae can also detect mount changes in water temperature and salinity. Lemon Sharks also have a homing sense which enables females to return to the same areas each year in order to give birth.

These sharks can orient themselves based on sound at a distance of about two meters, which is less than most large sharks.They can hear low frequencies best, with a low threshold of 40 hertz, but are also receptive to higher frequencies up to 320 Hertz.

Smell plays an important role for lemon sharks in food localization, predator detection, homing and navigation, and also likely in mating. It enables them to detect chemical cues at great distances because those cues can be transported on currents much farther than electric signals.

Lemon sharks have laterally mounted eyes with little overlap between their monocular fields of vision. They have vertically slit pupils which contract under bright light, and retinas with cones which allow them to see in color.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical
• electric electric

• Perception Channels
• visual visual
• acoustic acoustic
• chemical chemical
• electric electric

Food Habits

Young feed mostly on teleost fishes, crustaceans, and octopods. Older sharks eat mostly teleosts and cartilaginous fishes (other sharks), and sometimes even seabirds. Lemon sharks use sight, smell, hearing, and electrical sensitivity in order to locate food.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods

Predation

Adult lemon sharks have no predators. Juvenile sharks are occasionally eaten by adults or by other shark species.

Ecosystem Roles

Lemon sharks are hosts to a variety of endo- and ectoparasites, including copepod species and tapeworms. Remoras ( Echeneis naucrates ) are also commonly found on lemon sharks, though these two organisms share a symbiotic relationship. Remoras latch onto sharks for transportation and eat scraps from their meals. In return, Remoras eat dead skin and dermal parasites, keeping the sharks healthy.

Lemon sharks are apex predators, eating most smaller fish and crustaceans that are present in their habitats.

Economic Importance for Humans: Positive

Historically, many parts of the lemon shark were used and sold, including the hide for leather and the liver which was used to produce liver oil with a high vitamin content. The flesh was sometimes used for fertilizer or chicken feed, or dried for human consumption (Baughman and Springer, 1950). More recently, Negaprion are hunted for their use in shark fin soup, a highly profitable practice.

Due to its relative abundance in coastal water, its adaptability to laboratory conditions, and their phyletic position, sharks in the genus Negaprion are some of the most commonly studied sharks (Hueter and Gruber, 1982). They are well suited for experimental conditions because of their ability to ventilate their gills while stationary, which is an unusual trait among sharks.

Lemon sharks are also often used in aquariums because of their size and physical appearance.

• Positive Impacts
• food food
• body parts are source of valuable material
• research and education
• produces fertilizer

Economic Importance for Humans: Negative

Lemon sharks pose a very minimal threat to humans. There have been only 10 reports of unprovoked lemon shark attacks, none of which were fatal.

• Negative Impacts
• injures humans
  • bites or stings

Conservation Status

There are currently no conservation measures in place for any Negaprion species. Lemon sharks from the Atlantic and Pacific Oceans are listed as near threatened on the IUCN Red List. Sicklefin lemon sharks from the Indian Ocean is listed as vulnerable due to overfishing and habitat loss and isolation. Sicklefin lemon sharks are popular in shark fin soups and are occasionally still caught for meat. Their population is declining, but no conservation efforts have been initiated yet.

Additional Links

Encyclopedia of Life

Contributors

Elena Haverluk (author), Colorado State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Baughman, J., S. Springer. 1950. Biological and Economic Notes on the Sharks of the Gulf of Mexico, with Especial Reference to Those of Texas, and with a Key for their Indentification. The American Midland Naturalist , Vol. 44 No.1: 96-152. Accessed March 05, 2018 at https://www.jstor.org/stable/pdf/2421758.pdf?refreqid=search%3Ab86e241586fbbed655e80b1583f57646 .

Broyles, R. 2015. "Shark Phylogeny, Part 2: A Phylogeny Tree for Sharks" (On-line). Bright Hub Education. Accessed April 09, 2018 at https://www.brighthubeducation.com/science-homework-help/7274-a-phylogeny-tree-for-sharks/ .

Buray, N., J. Mourier, S. Planes, E. Clua. 2009. Underwater photo-identification of sicklefin lemon sharks, Negaprion acutidens, at Moorea (French Polynesia). Cybium , 33.1: 21-27. Accessed February 06, 2018 at https://www.researchgate.net/profile/Johann_Mourier/publication/256932926_Underwater_photo-identification_of_sicklefin_lemon_sharks_Negaprion_acutidens_at_Moorea_French_Polynesia/links/0046352a9efd0242b8000000.pdf .

Clua, E., N. Buray, P. Legendre, J. Mourier, S. Planes. 2010. Behavioural Response of Sicklefin Lemon Sharks Negaprion Acutidens to Underwater Feeding for Ecotourism Purposes. Marine Ecology Progress Series , 414: 257-266. Accessed February 06, 2018 at https://www.jstor.org/stable/pdf/24875219.pdf?refreqid=search%3A2d36a808acfb8d41059770095d988c9b .

Compagno, L. 2016. "Genus Negaprion" (On-line). Marine Species Identification Portal. Accessed March 23, 2018 at http://species-identification.org/species.php?species_group=sharks&menuentry=groepen&id=138&tab=beschrijving .

Cortes, E., S. Gruber. 1990. Diet, Feeding Habits and Estimates of Daily Ration of Young Lemon Sharks, Negaprion brevirostris (Poey). Copeia , 1990 no.1: 204-218. Accessed February 05, 2018 at https://www.jstor.org/stable/pdf/1445836.pdf?refreqid=search%3A554e86402d61584ec2ef68062ca93a68 .

Feldheim, K., S. Gruber, M. Ashley. 2002. The Breeding Biology of Lemon Sharks at a Tropical Nursery Lagoon. Proceedings: Biological Sciences , 269 no.1501: 1655-1661. Accessed February 06, 2018 at https://www.jstor.org/stable/pdf/3068131.pdf?refreqid=search%3A8216a9bbdc4768ed8663bf55bb13d3a4 .

Feldheim, K., S. Gruber, M. Ashley. 2001. Population genetic structure of the lemon shark (Negaprion brevirostris) in the western Atlantic: DNA microsatellite variation. Molecular Ecology , 10.2: 295-303. Accessed February 06, 2018 at https://s3.amazonaws.com/academia.edu.documents/33338461/025.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1517944432&Signature=gji0RWvvaseaTlpxCaQMU0DVM7c%3D&response-content-disposition=inline%3B%20filename%3DPopulation_genetic_structure_of_the_lemo.pdf .

Feldhiem, K., S. Gruber, M. Ashley. 2001. Multiple Paternity of a Lemon Shark Litter. Copeia , 2001 No. 3: 781-786.

Fields, D. 2007. The Shark's Electric Sense. Scientific American , Vol. 297 No. 2: 74-81. Accessed March 05, 2018 at http://www.jstor.org/stable/pdf/26069417.pdf?refreqid=excelsior%3Aa243b517cb6a38757f242e82d521710f .

Filmalter, J., L. Dagorn, P. Cowley. 2013. Spatial behaviour and site fidelity of the sicklefin lemon shark Negaprion acutidens in a remote Indian Ocean atoll. Marine Biology , 160 issue 9: 2425-2436. Accessed February 06, 2018 at https://link.springer.com/article/10.1007/s00227-013-2237-1 .

Gruber, S., D. Nelson, J. Morrissey. 1988. Patterns of activity and space utilization of lemon sharks, Negaprion brevirostris, in a shallow Bahamian lagoon. Bulletin of Marine Science , 43.1: 61-76. Accessed February 05, 2018 at https://www.researchgate.net/profile/John_Morrissey4/publication/233525742_Patterns_of_Activity_and_Space_Utilization_of_Lemon_Sharks_Negaprion_Brevirostris_in_a_Shallow_Bahamian_Lagoon/links/53fdb4ad0cf22f21c2f82915.pdf .

Hueter, R., S. Gruber. 1982. Recent Advances in Studies of the Visual System of the Juvenile Lemon Shark Negaprion Brevirostrus. Florida Scientist , Vol. 45 No. 1: 11-25. Accessed March 05, 2018 at http://www.jstor.org/stable/pdf/24320256.pdf?refreqid=excelsior%3Ad3a95c45bdd309d477d18e9d3c7305f8 .

Lutz, P. 2004. Biology of Sharks and Their Relatives . New York: CRC Press.

Morgan, A. 2018. "Negaprion Brevirostrus" (On-line). Florida Museum. Accessed February 19, 2018 at https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/negaprion-brevirostris/ .

Morissey, J., S. Gruber. 1993. Home Range of Juvenile Lemon Sharks, Negaprion brevirostris. Copeia , 1993 no.2: 425-434. Accessed February 06, 2018 at https://www.jstor.org/stable/pdf/1447141.pdf?refreqid=search%3A8216a9bbdc4768ed8663bf55bb13d3a4 .

Motta, P., T. Tricas, R. Summers. 1995. Feeding mechanism and functional morphology of the jaws of the lemon shark Negaprion brevirostris (Chondrichthyes, Carcharhinidae). Journal of Experimental Biology , 226: 309-329. Accessed February 06, 2018 at https://www.researchgate.net/profile/Cheryl_Wilga/publication/279204566_1995_Motta_Wilga_JMorph_anat_lemon/links/559069c408ae15962d8c4b02/1995-Motta-Wilga-JMorph-anat-lemon.pdf .

Mourier, J., N. Buray, J. Shultz, E. Clua, S. Planes. 2013. "Genetic Network and Breeding Patterns of a Sicklefin Lemon Shark (Negaprion acutidens) Population in the Society Islands, French Polynesia" (On-line). PLOS One. Accessed February 19, 2018 at http://journals.plos.org/plosone/article/authors?id=10.1371/journal.pone.0073899 .

Murray, R. 1961. The Response of Ampullae of Lorenzini of Eslamobranch to Electrical Stimulation. Journal of Experimental Biology , 39: 119-128. Accessed March 05, 2018 at http://jeb.biologists.org/content/jexbio/39/1/119.full.pdf .

Nelson, D. 1967. Hearing Threshold, Frequency Discrimination, and Acoustic Orientation in the Lemon Shark Negaprion brevirostrus. Institute of Marine Science, University of Miami : 741-768. Accessed March 05, 2018 at http://www.ingentaconnect.com/content/umrsmas/bullmar/1967/00000017/00000003/art00013?crawler=true&mimetype=application/pdf&casa_token=uNvBVLjns2MAAAAA:r7o2eohSg7zLGOdy6WW0_gzaBohMFwgLf6kE2U_smq-TvBRhH7QOB85lkFjaZ0Mi48YmRDf8r8x0BjVrQAg .

Schultz, J. 2008. Global phylogeography and seascape genetics of the lemon sharks (genus Negaprion). Molecular Ecology , 17.24: 5336-5348. Accessed February 05, 2018 at https://pdfs.semanticscholar.org/e228/42aecc8a0829b5c4411fc2b86457dd1e6127.pdf .

Smithsonian Ocean Portal, 2017. "Sharks" (On-line). Ocean Portal. Accessed April 09, 2018 at http://ocean.si.edu/sharks .

Stevens, J. 1984. Life-History and Ecology of Sharks at Aldabra Atoll, Indian Ocean. Proceedings of the Royal Society of London , 222: 79-106. Accessed February 05, 2018 at https://www.jstor.org/stable/pdf/36039.pdf?refreqid=search%3A554e86402d61584ec2ef68062ca93a68 .

Sundström, L. 2015. "Negaprion brevirostris" (On-line).

The IUCN Red List of Threatened Species(tm)

Tricia, M., S. Kajiura. 2010. Olfactory morphology and physiology of elasmobranchs. Journal of Experimental Biology . Accessed March 05, 2018 at http://jeb.biologists.org/content/213/20/3449.article-info .

Wetherbee, ., S. Gruber, R. Rosa. 2007. Movement patterns of juvenile lemon sharks Negaprion brevirostris within Atol das Rocas, Brazil: a nursery characterized by tidal extremes. Marine Ecology Progress Series , 343: 283-293. Accessed February 05, 2018 at https://www.jstor.org/stable/pdf/24871443.pdf?refreqid=excelsior%3A1cd76fa39f9dcfd9ed02dfa595baeb99 .

Yoshino, T., W. Hiramatsu, M. Toda, S. Uchida. 1981. New Records of Two Sharks, Nebrius concolor and Negaprion acutidens from Japanese Waters. Bulletin of the College of Science , 32: 37-46.

2018. "Lemon Shark – Negaprion brevirostris" (On-line). Facts About Animals. Accessed February 26, 2018 at http://www.facts-about.info/lemon-shark/ .

2018. "Lemon Shark" (On-line). Arkive. Accessed February 19, 2018 at http://www.arkive.org/lemon-shark/negaprion-brevirostris/ .