Is the "Sand Tiger" Shark Really a Tiger? Its Name, Its Teeth, and Its Habit of Swallowing Air

1. Why a Shark Is Called a "Sand Tiger" (and Has Other Names Too)

The sand tiger shark (Carcharias taurus) has different common names in different places. The Florida Museum lists "sand tiger shark" for the United States, "grey nurse shark" for Australia, and "spotted raggedtooth shark" for South Africa. [1] In Japan it is called shirowani, and "wani" is an old Japanese word that can mean a shark, as well as the animal we call a crocodile. So a Japanese aquarium visitor may also ask whether this fish is a crocodile. [3]

The "tiger" part is harder to explain. The Aquarium of the Pacific says it is rumored that aquariums are the source of the "tiger" in the name. [2] That is a rumor, not a documented fact, so treat it as a guess.

What is clear is who it is not. English Wikipedia notes that, despite its names, the sand tiger is not closely related to either the tiger shark or the nurse shark. [4] Wikipedia gives the origin of "sand" as sandy shorelines. [4] Next, those teeth.

2. What the Sand Tiger Shark's Sticking-Out Teeth Are For

The sand tiger's mouth stays slightly open, so its teeth show even when it is calm. The Aquarium of the Pacific describes three rows of long, needle-like front teeth that stick out, with flatter teeth at the back. [2] The Florida Museum describes long, narrow main points with small extra points on each side, and says the ragged look gives the shark a menacing appearance. [1]

Looking scary does not mean acting aggressively. These sharks mostly eat bony fish such as herring, bluefish, and flatfish, and the aquarium adds rays, small sharks, crabs, lobsters, and squid. [1] [2] Long, narrow teeth are the kind that hold on to a slippery fish. That is a reasonable reading of the sources rather than something they state in so many words.

3. Are Sand Tiger Sharks Dangerous to People?

The Florida Museum says they are not aggressive unless provoked. The International Shark Attack File records 29 unprovoked sand tiger shark bites on people. None was fatal. Some bites happened when people were spearfishing and carrying fish they had caught. [1] The Aquarium of the Pacific says they do not pose a threat to humans. [2]

This is one reason they are common in public aquariums: the Florida Museum reports that the oldest recorded aquarium sand tigers have lived to 24 years. [1] Like any large wild animal, a sand tiger should still be left alone. If you meet one in the ocean, look and do not touch.

That calm, hovering style of swimming is also the key to the shark's best trick.

4. How Swallowing Air Helps a Sand Tiger Shark Float

Most fish with bones have a swim bladder, a gas-filled organ that helps them stay afloat. Sharks do not have one. The Florida Museum explains that the sand tiger is denser than water and lacks a swim bladder. It comes to the surface, gulps air, and holds it in its stomach, which lets it hover motionless in the water. [1]

The Aquarium of the Pacific agrees: the air lets sand tigers hover near the seafloor with little effort. [2] English Wikipedia describes this as unique among sharks. [4] Japanese Wikipedia likewise says the sand tiger takes in air at the surface and stores it in its stomach in place of a swim bladder. [3]

So the next time a sand tiger seems to be doing nothing, it may be using a trick no other shark is known to use.

5. How to Watch a Sand Tiger Shark Yourself

At an aquarium, try three things. First, look at the mouth: can you see the teeth when the shark is calm? Second, watch how it moves: does it glide slowly, or hover almost still? Third, watch the surface: does it ever rise and take a gulp of air?

Then compare. Look up the common names in a field guide or the aquarium's sign. Which animal is each name borrowed from, and does the name match how the animal behaves? The Florida Museum and the Aquarium of the Pacific species pages are good places to keep reading.

Sources

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