The silhouette of a massive shark lurking below the ocean's surface doesn't exactly conjure up images of a laid-back creature that prefers to chill with its posse. But research shows there's a yellow-hued giant — the lemon shark (Negaprion brevirostris) — who isn't a fan of aggression and seems to have quite the social life.
Lemon sharks hang out in subtropical, coastal waters and can grow up to 10 feet (3 meters), weigh up to 551 pounds (250 kilograms) and live to be up to 30 years old. Besides sporting an unusual skin color for a shark, they're recognizable by their short, blunt snout and two similar-sized triangular fins on their back, positioned behind the pectoral fin.
Why Are They Yellow?
Lemon sharks aren't necessarily as brightly colored as their name suggests, but their yellowish-brown hue is still noticeable — and quite valuable to this shark in terms of survival. The color helps the sharks blend in with the sandy seafloor, making it a whole lot easier to catch their next meal.
What's on Their Dinner Menu?
Lemon sharks mostly chow down on bony fish, crustaceans and an occasional seabird, but they're also part of the 1 percent of fish that practice cannibalism — large adult lemon sharks are known to eat smaller lemon sharks or babies.
We humans may not be on their dinner menu, but in some areas, they're on ours. Lemon sharks are hunted commercially and recreationally, and their fins are sold for shark fin soup — an often illegal delicacy — and their skin is sold for leather.
Are Lemon Sharks Dangerous?
Given their penchant for subtropical shallow water, they're in frequent proximity to swimmers, surfers and divers. But according to the International Shark Attack File, there have been only 10 attacks ever documented on humans by lemon sharks — and none were fatal. While they do seem a bit like the Casper the Friendly Ghost of the sea, it's important to remember lemon sharks are predators near the top of the ocean food chain and could still bite when they themselves get spooked.
They Enjoy Social Gatherings
They don't exactly get together for a night out on the town, but there's growing evidence that many sharks — the lemon shark included — are quite social and hang out in groups. "Juvenile lemon sharks do show evidence of being social, both in captive and wild settings. This is most likely defensive and increases their chance of seeing an incoming predator. However there may be other advantages as well. The adults appear to be less social, but again there do appear to be times (and locations), where they form groups," explains Yannis Papastamatiou, Florida International University associate professor in biology, in an email interview.
Where Do Lemon Sharks Live?
The lemon shark is found in subtropical shallow water in depths up to 300 feet (90 meters). And they can be found over quite a large area, extending from the coast of New Jersey in the U.S. to Southern Brazil, the Gulf of Mexico and the Caribbean in the northwestern Atlantic Ocean, and along Senegal and the Ivory Coast of Africa in the eastern Atlantic. They also live in the Northern Pacific, stretching from the Gulf of California and Baja California all the way south to Ecuador.
When migrating, they head out to oceanic waters, but tend to stay close to the coast. They're also sometimes enter freshwater, but don't worry, they can't stay there for long.
Researchers Love Them
Lemon sharks do well in captivity and play a big role in helping scientists understand sharks as a species. According to Florida International University distinguished postdoc fellow Diego Cardeñosa, in an email interview, the abundant research can be attributed to "the late Dr. Samuel Gruber, who studied lemon sharks in Bimini, Bahamas for decades. Dr. Gruber built a research station in Bimini in the early 1990s — and since then the Bimini Sharklab has been a major platform for many scientists around the world, including myself, to gain research experience with sharks in the field. The lemon shark is a highly abundant species in Bimini and Dr. Gruber's team uses it as a model species for many studies on behavior, physiology, ecology and conservation."
Are Lemon Sharks Endangered?
Cardeñosa studied with Dr. Gruber in Bimini to monitor the impact of habitat loss on the growth and survival rate of juvenile lemon sharks. "The status of lemon sharks is currently Near Threatened by the IUCN Red List of Threatened Species. The major threats for lemon sharks are overfishing and habitat loss. As with many other sharks, this species is caught in commercial, artisanal and recreational fisheries across its habitat range. Habitat loss through mangrove ecosystem degradation is also a major threat for this species as it uses these habitats as nursery grounds," he shares.
The lemon shark is breaking color stereotypes, keeping their friends close and boosting our understanding of sharks. And if you're going swimming with sharks on your next adventure vacation, you might just get to be social with one of nature's gigantic yellow marvels.