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Shattering Shark Myths

 Time to shatter some shark myths, don’t you think?

Tiger shark. Credit: NOAA.


Gray reef shark.  Credit: NOAA.

Blacktip shark. Credit: NOAA. 

 MYTH: Sharks don't get cancer.  

Sharks can get cancer, and other types of disease, but it is thought that they might have lower incidence of disease than other animals. This myth is based on sharks having skeletons of cartilage, which has led to a demand for shark cartilage products. Learn more from the Pharmaceutical Intelligence.

MYTH: All sharks need to swim constantly to breathe.

FACT: Sharks need to move water over their gills to absorb oxygen from the water. To do this they can either swim through the water (ram ventilation) or pump water over their gills (buccal pumping). Some species, like nurse and angel sharks, pump water over their gills and spend a most of their time on the ocean floor. Other species, like hammerhead sharks must swim continuously to ventilate their gills.

 MYTH: Sharks feed at night.

FACT: In general, shark feeding is not synchronized with any particular time of the day. While some sharks hunt more actively during the night, like some reef sharks, other sharks feed during the day and/or around the clock. Highly visual predators like the white shark often feed during daylight hours. Most sharks are opportunistic predators and will feed when the opportunity arises.
 MYTH: All sharks are apex predators.

FACT: Apex predators, also known as alpha, super, top or top-level predators, are predators with few to no predators of their own, residing at the top of their food chain. Not all sharks are apex predators. Depending on the species, sharks can occupy multiple trophic levels. While species like tiger sharks occupy the top of the food chain and are considered apex predators, other species like bonnethead sharks are found in the middle of the food chain.
 MYTH: All shark species are in peril.

Not all shark species are in trouble. In fact, under fishery management plans implemented by NOAA Fisheries, spiny dogfishand Gulf of Mexico blacktip sharks have been fully rebuilt from being overfished. A number of other sharks are not subject to overfishing such as the north Atlantic population of blue shark, U.S. south Atlantic population of Atlantic sharpnose shark, and bonnethead sharks. Evidence also suggests that both white shark and thresher shark populations are increasing. Learn more for the Southwest Region and highly migratory species research.

MYTH: Any shark caught in shallow water is called a sand shark.

FACT: There is no such shark species with that accepted common name. Some of the species that are often called “sand sharks” by beachgoers include sandbar sharks (Carcharhinus plumbeus), sand tiger sharks (Carcharias taurus), and smooth dogfish (Mustelus canis).

 MYTH: Sharks have poor vision.

FACT: Sharks eyes have a tapetum lucidum, a layer of mirrored crystals located behind the retina. This enables sharks to see even in dark or murky water and up to ten times greater than humans in clear water.
 MYTH: White sharks are killing machines.

These sharks are not the killing machines that Hollywood has made them out to be. White sharks are large predators, but they do not target humans for prey and don’t have any malicious intent.  Much like lions in Africa and other wild animals, white sharks they can be unpredictable, but they deserve our respect and should be treated with caution. Some disturbing images of thrill seekers free swimming with white sharks at Guadalupe Island has had long time researchers in that zone cringing at thought of an attack that could jeopardize future access and research efforts. 
 MYTH: All sharks are large.

FACT: Many shark species are rather small.  Most dogfish do not grow larger than 3 feet.  The smallest known shark, the dwarf lanternshark, has a maximum size of only 8 inches.

 MYTH: We don’t protect sharks in the United States.

FACT: The United States has some of the strongest shark management measures worldwide. NOAA Fisheries directly manages the federal shark fisheries in the Atlantic Ocean and Gulf of Mexico and works with U.S. regional fishery management councils to conserve and sustainably manage sharks in the Pacific Ocean. By conducting research, routinely assessing stocks, working with U.S. fishermen, and implementing restrictions when necessary, NOAA Fisheries sustainably manages shark populations. Learn more about U.S. shark conservation.

 MYTH: The United States is changing its laws to allow shark finning.

FACT: Absolutely not. In the United States, federal law prohibits “shark finning,” the process of removing shark fins at sea and discarding the rest of the shark. In fact, this practice has been prohibited by federal law since 2000 and shark conservation was further strengthened in 2010 when Congress passed the Shark Conservation Act. The Shark Conservation Act requires that all sharks in the United States, with one exception for smooth dogfish in the Atlantic, be brought to shore with their fins naturally attached. Learn more shark conservation in the United States and abroad.

 MYTH: If you cut off the fin of a shark, it will grow back and the shark will survive.

FACT: If a shark has its fin removed and is consequently returned to the ocean, under almost all circumstances the shark will not survive. Unlike salamanders or sea stars that can regrow limbs that have been cut off, sharks do not possess any regenerative properties that would allow them to regrow their fins.

 MYTH: Sharks can’t hear very well.

FACT: Hear this—sharks have an excellent sense of hearing, with ears located inside their heads on both sides rather than external ears like humans. Sharks can hear best at frequencies below 1,000 Hertz which is the range of most natural aquatic sounds. This sense of hearing helps sharks locate potential swimming and splashing prey in the water. They also use their lateral line system to pick up vibrations and sounds.

 MYTH: Sharks don’t lay eggs; they only give live birth.

FACT: Of the approximately 400 species of sharks, about 40 percent lay eggs. This is called oviparity. When the eggs are laid, they are in a protective egg case which sometimes washes up on the beach and is commonly called a "mermaid's purse." The egg case has tendrils allowing it to attach to a substrate such as corals, seaweed, or the ocean bottom.  In some species, such as the horn shark, the egg cases are pushed into the bottom or into crevices between or under rocks. Some shark species that do lay eggs include bamboo sharks, carpet sharks, Horn (bullhead) sharks, swell sharks, and many types of catsharks.