If you’ve ever been to a major aquarium, there’s a good chance you've been face to fin with a sand tiger shark. Here’s everything you should know about this wicked-looking—but pretty mild-mannered —creature.
1. IT BELONGS TO THE SAME ORDER OF SHARKS AS THE GREAT WHITE.
The sand tiger shark (Carcharias taurus) isn't related to the tiger shark (Galeocerdo cuvier), but it does have something in common with another popular species—the great white (Carcharodon carcharias). They're both Lamniformes, an order of sharks that share a signature look: five pairs of gill slits, two dorsal fins without spines, a relatively big mouth, and a lack of nictitating membranes, the protective, see-through shields over the eyes that many other sharks possess. Other Lamniformes are the basking shark, the goblin shark, and the prehistoric megalodon shark. True tiger sharks don’t make the cut; they’re part of a different order known as the Carcharhiniformes.
2. THOSE SCARY TEETH ARE LIKE DENTAL FISHING HOOKS.
Look at a sand tiger and the first thing you’ll notice will probably be its long, outward-pointing teeth, which remain visible even when the shark’s mouth is closed. Curved, slender, and serration-free, the teeth are perfect for puncturing the skins of small to mid-sized fish: slippery animals that can be hard to grab onto. This is in marked contrast to both the can-opener-shaped teeth we see in “real” tiger sharks and the thick slicing teeth of big-game hunters like great whites.
3. SAND TIGERS GULP AIR TO STAY BUOYANT.
By swallowing mouthfuls of air at the ocean’s surface, sand tigers can turn their stomachs into air pockets. Doing so helps the fish keep a neutral buoyancy level under the surface, enabling them to hover around motionlessly. (When it descends, the animal releases air bubbles out of its mouth.) No other shark exhibits this air-gulping behavior.
4. VIOLENT ENCOUNTERS WITH HUMANS ARE RARE.
Sand tigers tend to shy away from people, but they have been known to steal fish from spear- and net-hunters. That can bring them into conflict with humans, and when the sharks feel threatened, they may bite back in self-defense.
Still, according to the International Shark Attack File (ISAF), a global database maintained by the Florida Museum of Natural History, sand tigers have only been implicated in 29 “unprovoked attacks” on human beings since 1580. None of those attacks were fatal.
5. OVERFISHING HAS HURT THE SPECIES.
Sand tigers might not pose much of a threat to us, but through sport and commercial fishing, we’ve done a number on them.
Full-grown sand tigers are around 10 feet long and can weigh over 400 pounds. For decades, their intimidating size made the sharks prized trophies amongst recreational fishermen. From June to September 1918, 1900 sharks—primarily sand tigers—were caught in the area of Nantucket Sound. They continue to be hunted in some corners of the world for their meat, skin, teeth, and fins.
Because sand tigers tend to mate near shorelines, it's easy to net large numbers of them during the breeding season. Scientists estimate that the population living along the U.S. eastern seaboard shrank by 70 to 90 percent in the late 20th century due to overzealous commercial fishermen. A slow reproductive rate further handicaps the species, as does coastal pollution in the estuaries where their young tend to reside.
The International Union for Conservation of Nature (IUCN) lists the sand tiger shark as “vulnerable”—the ranking given to creatures that are at risk of becoming endangered. Sand tigers now enjoy protected status in Australia and the United States.
6. IT’S CALLED THE “GREY NURSE SHARK” IN AUSTRALIA.
This is another name which doesn’t make evolutionary sense because the species isn’t related to actual nurse sharks. Sand tigers have also been referred to as “spotted ragged tooth sharks” because adults and juveniles occasionally come with reddish-brown spots on their backsides.
7. EMBRYOS CANNIBALIZE EACH OTHER.
Not all of them will be born, though—in fact, the majority won’t. About five months into a nearly year-long gestation, a few of the eggs will begin to hatch and swim around the uterus. And they're hungry. To survive, the biggest fetuses devour unhatched eggs and smaller, weaker siblings who have already hatched out. When the mother finally gives birth, only two shark pups will remain—one for each uterus.
By shark standards, newborn sand tigers are exceptionally large, stretching up to 3 feet long apiece. At that size, the juvenile sharks have an easy time fighting off many would-be predators after they're born. Bulking up on their siblings beforehand might be a secret of survival.
The practice might also be a matter of sexual selection: Female sand tigers tend to mate with several different partners each breeding season, and it's been hypothesized that the eggs from the first encounter will be the earliest to fertilize. As a consequence, they’ll grow faster and be more likely to gobble up all the rival fetuses sired by other males. So in theory, a female sand tiger could choose to mate with her preferred partner first, giving his unborn offspring the best chance of survival.
8. LONG ISLAND HAS A SAND TIGER NURSERY.
To get away from adults who might attack them, pups (a.k.a. juvenile sharks) often spend a few months out of every year in shark nurseries: shallow, relatively secluded parts of the ocean where full-grown sharks are less common than they might be elsewhere. In 2016, researchers identified Great South Bay, a watery divide between Long Island and Fire Island, as a sand tiger nursery. It was discovered after a catch-and-release program noticed that young sand tigers who’d been fitted with tags were coming back to the same lagoon summer after summer. Other verified sand tiger nurseries include Massachusetts’s Plymouth and Duxbury Bays.
9. AQUARIUMS HAVE HAD A LOT OF SUCCESS WITH SAND TIGERS.
Tiger sharks and great whites are ill-suited for captivity, but sand tigers do well—given the right setup and proper care, sand tigers can live for decades in aquariums. One female named Bertha lived at the New York Aquarium in Coney Island for over 40 years before dying in 2008. (Attempts to breed sand tigers in captivity seldom work out, but some facilities like the now defunct Manly Sea Life Sanctuary in Australia had some success.)
To keep them in mixed-species tanks, staff members do their best to ensure that the sharks are well-fed at all times. At the Tennessee Aquarium, for example, the resident sand tigers are fed three times every week, with each individual receiving enough food per session to equate to around 2 percent of its body weight. This strategy discourages captive sharks from trying to eat live tankmates—although they may still nibble on the other fish every so often.
10. THE SHARKS LIKE TO CREEP AROUND SHIPWRECKS.
North Carolina’s outer banks are home to more than 2000 documented shipwrecks, earning it the nickname “Graveyard of the Atlantic.” Smaller fish are liable to transform ship remains into faux reefs, unwittingly attracting predatory sand tigers, who like to hunt on the sea floor. In the Graveyard of the Atlantic, divers have reported seeing over 100 sand tigers around a single wreck.
11. SAND TIGERS CAN HUNT COOPERATIVELY.
In 1915, American ichthyologist Russell J. Coles was monitoring fish off of Cape Lookout in North Carolina when he saw a gang of at least 100 sand tigers surround a school of bluefish. Working together, the sharks drove their victims into very shallow waters and then attacked them. On another occasion, a group of sand tigers near New South Wales started flailing their tails about like bullwhips, producing cracking noises that the sharks used to corral some yellowtail kingfish into a tight, vulnerable cluster—just in time for lunch.