Sand sharks, also known as sand tiger sharks or gray nurse sharks, are stocky sharks with large, stout bodies and a large second dorsal fin. They belong to the lamniform order of the Odontaspididae family of sharks. They are known as sand sharks because of their tendency to inhabit shallow water close to the shore.
Facts about Sand Sharks
If sand sharks are considered aggressive and ferocious, it is largely because of their appearance. They can be distinguished from other sharks by their large second dorsal fin and fang-like teeth, which are visible even when their mouth is shut. They are brownish-gray in color, with bronze or rust-colored spots on top and white underneath. They have flat, cone-shaped snouts, and a notched, oblong tail. On an average, they weigh around 159 kg and measure around 3.2 meters in length.
Habitat and Distribution
Sand sharks inhabit almost all tropical and subtropical oceans, but they are mainly found in the coastal waters of the Atlantic, on both the sides, in the western Indian Ocean and also in the Gulf of Maine. They are also found in small numbers in the Adriatic and Mediterranean seas. Their habitats include coral reefs, estuaries, and coastal waters.
Males reach maturity when they are around 2-meters long, while females reach maturity when they are 2.2-meters long. They just develop two embryos out of the large number of eggs that hatch within the parent shark. The developed embryos obtain nourishment from feeding on the unfertilized eggs in a process which is known as 'intrauterine cannibalism'. Their gestation period lasts for around 9 to 12 months. The newborns are roughly around a meter long.
Sand sharks mainly feed on small fish, like mackerel, cunners, skates, menhaden, flounders, butterfish, scup, bonito, silver hake, etc. Their diet may also consist of other marine species, such as squids, lobsters, crabs, small sharks, and rays.
Temperament and Lifestyle
These sharks are sluggish, docile, and non-aggressive as long as they are not threatened. They prefer to swim solo, and are usually seen feeding at night. They are the only species of sharks that are known to rise to the surface of the water to gulp air, which they hold in their stomach. They practice this to keep themselves buoyant, as their dense body structure can cause them to sink. In winter, they move towards deeper coastal waters.
Sand sharks have an extremely low rate of reproduction. At the same time, they are susceptible to exploitation by fisheries and are also killed in large numbers for their oil and fins. In fact, it is one of the many species which are bearing the brunt of flourishing Asian shark-fin trade. They are enlisted as vulnerable species by the International Union for Conservation of Nature. Measures are being taken to protect them from exploitation and extinction.
Sand sharks are highly adaptable to aquarium life. In fact, they belong to the elite group of sharks that are found in almost all the walk-through oceans in the world.