Sand Tiger Shark
Carcharias taurus
Sand tiger sharks are also known as spotted raggedtooth, ground, or gray nurse sharks. It is rumored that aquariums are the source of the “tiger” in the sand tiger name. Originally called sand sharks, the tiger was added to make them seem more ferocious. All sharks in this family swim slowly with their mouths open, exposing long, narrow, needle-like teeth. They belong to a group of sharks known as ram ventilators that need constant movement to pass water over their gills to breathe. They often find fast-moving currents to help them breathe while exerting less energy. Sand tiger sharks have been observed “gulping” air, using a stomach full of air to help maintain neutral buoyancy.
SPECIES IN DETAIL
Sand Tiger Shark
Carcharias taurus
CONSERVATION STATUS: Critically endangered
CLIMATE CHANGE: Not Applicable
Geographic Distribution
Western and eastern Atlantic Ocean, western Indian Ocean, western Pacific Ocean, and western Mediterranean Sea.
Habitat
Sand tigers are mainly found in temperate and tropical waters in shallow bays and sandy coastal waters and on rocky or coral reefs to depths from the surf line to about 190 m (625 ft). They spend most of their time near the bottom. In some areas these sharks make seasonal migrations associated with reproduction, moving to warmer waters to give birth.
Physical Characteristics
Sand tigers are large sharks with a stout, bulky, fusiform body (tapered at both ends), an upturned, short, pointed, flattened snout, and a pronounced subterminal notched caudal fin. Three rows of long needle-like front teeth protrude from their open mouth. The back teeth are molar-like. Their two dorsal fins and anal fins are similar in size.They do not have a nictitating membrane (extra eyelid) with which to protect their eyes during feeding or attacks as many other sharks do.
They are light-brown to gray colored on their upper body gradually fading to a white color below. Juveniles have small yellowish-red or brownish spots scattered on the rear of their body and tail that fade with age.
Size
Males average 2.2-2.6 m (7-8.5 ft) in length and females 2.3-3.0 m (7-9.8 ft). These sharks have been known to reach a length of 3.2 m (10.5 ft) and a weight of 159 kg (350 lb).
Diet
These voracious sharks consume large and small bony fishes, small sharks, rays, crabs, lobsters, and squid. Primarily nocturnal hunters, they feed cooperatively with other sand tiger sharks, surrounding and herding schooling prey.
Reproduction
Sand tiger sharks are ovophagous. Females have two uterine chambers where 16 to 23 eggs each are fertilized internally. Early in development the embryos receive their nourishment from their egg yolk. When they are about 10 cm (4 in) in length, the yolk is exhausted. At the same time the mouth of the embyro becomes functional and teeth are formed.
Eggs hatch in the uterine chamber when the embryos are about 17 cm (6.7 in) in length. The largest and most advanced embryo in each chamber (usually the first hatched) kills and consumes younger developing siblings (intrauterine cannibalism). After preying on their siblings, the two remaining embryos feed on any eggs present. After a gestation period of eight to nine months, two pups are born, one from each uterine chamber. Pups are 95 to 105 cm (37 to 41 in) long at birth.
Sand tiger sharks have the lowest reproductive rate known for sharks. They produce only two large pups, one from each uterine cavity, every two years.
Behavior
They are strong but slow-moving, relatively sluggish sharks that spend most of their time near the bottom looking for food. They swim to the surface of the water to gulp and swallow air, retaining it in their stomach to create near neutral buoyancy that allows them to remain virtually motionless above the ocean floor. They are the only known shark to do this.
Adaptation
Like most sharks, sand tigers are able to detect electrical signals emitted by potential prey in the water column or substrate with specialized electrosensory organs on the sides of their head and lower jaw called ampullae of Lorenzini that enable them to find prey in murky water. They have a series of small pores that run the length of their body, known as a lateral line, which allows them to sense water movement around their body to a distance of approximately 300 feet. This aids in both the detection of predators and potential food sources. They also have acute senses of smell, touch, and hearing. They have good vision, are very sensitive to low-light conditions, and are able to discriminate between light and dark objects. Their adaptations of electrical reception, smell, and hearing combine to make them efficient and feared predators.
The countershading of their body is a protective camouflage. If a predator looks down at the shark, its dark top blends into the dark ocean below. Viewed from below, the light color of the bottom of its body blends into the ligher water column above.
Longevity
Estimates of longevity in the sand tiger shark vary, ranging from fifteen to forty years. This variation appears to be related to geographic location of the studied shark population and may indicate some local environmental issues impacting lifespan.
Conservation
Conservation status of the sand tiger shark varies based on the geographic region. Globally they are listed as vulnerable, while in the areas of the western Mediterranean, Europe, and eastern Australian coast they are rated as critically endangered due to commercial fishing. In these areas and in the western Pacific this species is the target of “finning,” in which sharks are caught for their fins. Regulations to protect the sand tiger shark have been established in Europe, the Mediterranean, eastern Australia, and eastern coast of the U.S.
Fished commercially in all areas of their range, they are being pushed to commercial extinction because of overfishing. Their predictable habits, schooling, and low reproduction rates have all contributed to their serious population reduction.
Studies have shown that the growth of shark ecotourism, while controversial, has had a positive impact on the public impression of sharks and the need for increased conservation efforts.
Special Notes
The effective range of a shark’s ability to detect electrical signals is about 20 to 30 cm (1 ft.)
Although their many rows of teeth are often highly visible, they are not an aggressive shark and do not pose a threat to humans. Most of the available information about sand tiger sharks comes from observations and studies conducted in aquariums.
SPECIES IN DETAIL | Print full entry
Sand Tiger Shark
Carcharias taurus
CONSERVATION STATUS: Critically endangered
CLIMATE CHANGE: Not Applicable
Western and eastern Atlantic Ocean, western Indian Ocean, western Pacific Ocean, and western Mediterranean Sea.
Sand tigers are mainly found in temperate and tropical waters in shallow bays and sandy coastal waters and on rocky or coral reefs to depths from the surf line to about 190 m (625 ft). They spend most of their time near the bottom. In some areas these sharks make seasonal migrations associated with reproduction, moving to warmer waters to give birth.
Sand tigers are large sharks with a stout, bulky, fusiform body (tapered at both ends), an upturned, short, pointed, flattened snout, and a pronounced subterminal notched caudal fin. Three rows of long needle-like front teeth protrude from their open mouth. The back teeth are molar-like. Their two dorsal fins and anal fins are similar in size.They do not have a nictitating membrane (extra eyelid) with which to protect their eyes during feeding or attacks as many other sharks do.
They are light-brown to gray colored on their upper body gradually fading to a white color below. Juveniles have small yellowish-red or brownish spots scattered on the rear of their body and tail that fade with age.
Males average 2.2-2.6 m (7-8.5 ft) in length and females 2.3-3.0 m (7-9.8 ft). These sharks have been known to reach a length of 3.2 m (10.5 ft) and a weight of 159 kg (350 lb).
These voracious sharks consume large and small bony fishes, small sharks, rays, crabs, lobsters, and squid. Primarily nocturnal hunters, they feed cooperatively with other sand tiger sharks, surrounding and herding schooling prey.
Sand tiger sharks are ovophagous. Females have two uterine chambers where 16 to 23 eggs each are fertilized internally. Early in development the embryos receive their nourishment from their egg yolk. When they are about 10 cm (4 in) in length, the yolk is exhausted. At the same time the mouth of the embyro becomes functional and teeth are formed.
Eggs hatch in the uterine chamber when the embryos are about 17 cm (6.7 in) in length. The largest and most advanced embryo in each chamber (usually the first hatched) kills and consumes younger developing siblings (intrauterine cannibalism). After preying on their siblings, the two remaining embryos feed on any eggs present. After a gestation period of eight to nine months, two pups are born, one from each uterine chamber. Pups are 95 to 105 cm (37 to 41 in) long at birth.
Sand tiger sharks have the lowest reproductive rate known for sharks. They produce only two large pups, one from each uterine cavity, every two years.
They are strong but slow-moving, relatively sluggish sharks that spend most of their time near the bottom looking for food. They swim to the surface of the water to gulp and swallow air, retaining it in their stomach to create near neutral buoyancy that allows them to remain virtually motionless above the ocean floor. They are the only known shark to do this.
Like most sharks, sand tigers are able to detect electrical signals emitted by potential prey in the water column or substrate with specialized electrosensory organs on the sides of their head and lower jaw called ampullae of Lorenzini that enable them to find prey in murky water. They have a series of small pores that run the length of their body, known as a lateral line, which allows them to sense water movement around their body to a distance of approximately 300 feet. This aids in both the detection of predators and potential food sources. They also have acute senses of smell, touch, and hearing. They have good vision, are very sensitive to low-light conditions, and are able to discriminate between light and dark objects. Their adaptations of electrical reception, smell, and hearing combine to make them efficient and feared predators.
The countershading of their body is a protective camouflage. If a predator looks down at the shark, its dark top blends into the dark ocean below. Viewed from below, the light color of the bottom of its body blends into the ligher water column above.
Estimates of longevity in the sand tiger shark vary, ranging from fifteen to forty years. This variation appears to be related to geographic location of the studied shark population and may indicate some local environmental issues impacting lifespan.
Conservation status of the sand tiger shark varies based on the geographic region. Globally they are listed as vulnerable, while in the areas of the western Mediterranean, Europe, and eastern Australian coast they are rated as critically endangered due to commercial fishing. In these areas and in the western Pacific this species is the target of “finning,” in which sharks are caught for their fins. Regulations to protect the sand tiger shark have been established in Europe, the Mediterranean, eastern Australia, and eastern coast of the U.S.
Fished commercially in all areas of their range, they are being pushed to commercial extinction because of overfishing. Their predictable habits, schooling, and low reproduction rates have all contributed to their serious population reduction.
Studies have shown that the growth of shark ecotourism, while controversial, has had a positive impact on the public impression of sharks and the need for increased conservation efforts.
The effective range of a shark’s ability to detect electrical signals is about 20 to 30 cm (1 ft.)
Although their many rows of teeth are often highly visible, they are not an aggressive shark and do not pose a threat to humans. Most of the available information about sand tiger sharks comes from observations and studies conducted in aquariums.