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. (Carpenter, 2010; Compagno, et al., 2005; Gruber, 2004; Morgan, 2011; Sundstrom, 2011)
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. (Compagno, et al., 2005; Morgan, 2011; Sundstrom, 2011)
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). (Carpenter, 2010; Sundstrom, 2011)
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. (Morgan, 2011)
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. (Feldheim, et al., 2002; Feldheim, et al., 2004; Morgan, 2011)
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. (Chapman, et al., 2009; Feldheim, et al., 2002; Feldheim, et al., 2004; Morgan, 2011)
Following mating, there is parental involvement by male lemon sharks. Females gestate young for 10-12 months. (Morgan, 2011)
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. (Carpenter, 2010; Sundstrom, 2011)
Lemon sharks are usually solitary, but they been found in groups of up to 20 individuals based on sex and size, often around fishing docks. They are active throughout the day, but are most active at dusk and dawn. (Carpenter, 2010; Compagno, et al., 2005; Morgan, 2011)
Juvenile lemon sharks stay in the nursery areas in which they were birthed until they are large enough to be able to survive in deeper waters. Their activity areas are typically just a few square kilometers, whereas adults may range within several hundred square kilometers. This species is also migratory, though not much is currently known about their habits during migration periods. (Morgan, 2011; Sundstrom, 2011)
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 nigricans), 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. (Feldheim, et al., 2002; Gruber, 2007; O'Connell, 2008; Reader's Digest Association, 1987)
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 hystrix), 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). (Carpenter, 2010; Morgan, 2011; Sundstrom, 2011)
While adult lemon sharks may occasionally eat juveniles, there are no known predators of adult lemon sharks. (Morgan, 2011)
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. (Bailly, 2012; "Negaprion brevirostris (POEY, 1868)", 2013; Mustard, 2013)
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. (Carpenter, 2010)
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. (Carpenter, 2010; Morgan, 2011)
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. (IUCN, 2012; Sundstrom, 2011)
Alexander Lister (author), Sierra College, Jennifer Skillen (editor), Sierra College, Jeremy Wright (editor), University of Michigan-Ann Arbor.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
uses sound to communicate
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
active at dawn and dusk
a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
uses electric signals to communicate
parental care is carried out by females
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
Animals with indeterminate growth continue to grow throughout their lives.
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
Referring to a mating system in which a female mates with several males during one breeding season (compare polygynous).
structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
uses touch to communicate
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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Gruber, S. 2007. "Lemon shark fact file" (On-line). ARKive. Accessed January 25, 2013 at http://www.arkive.org/lemon-shark/negaprion-brevirostris/.
Gruber, S. 2004. "Research: Early Life History" (On-line). Bimini Biological Research Station. Accessed January 25, 2013 at http://www6.miami.edu/sharklab/research_earlylife.html.
IUCN, 2012. "The IUCN Red List of Threatened Species" (On-line). Accessed January 26, 2013 at www.iucnredlist.org.
Morgan, A. 2011. "Lemon Shark" (On-line). Ichthyology. Accessed October 10, 2011 at http://www.flmnh.ufl.edu/fish/gallery/descript/lemonshark/lemonshark.html.
Mustard, A. 2013. "Lemon shark (Negaprion brevirostris) accompanied by Remoras (Echeneis naucrates) at night. Little Bahama Bank. Bahamas. Tropical West Atlantic Ocean." (On-line image). Animals and Earth. Accessed January 25, 2013 at http://www.animalsandearth.com/en/photo/view/id/137022-lemon-shark-negaprion-brevirostris-accompanied-by-remoras-echeneis-naucrates-at-night-little-bahama-bank-bahamas-tropical-west-atlantic-ocean#/1/tag/Negaprion%20Brevirostris/undefined/.
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Reader's Digest Association, 1987. Sharks: Silent Hunters of the Deep. New York, CA: Reader's Digest Services Pty Ltd..
Sundstrom, L. 2011. "Negaprion brevirostris" (On-line). Accessed October 05, 2011 at http://www.iucnredlist.org/apps/redlist/details/39380/0.