Carchariidae

A fascinating group of sharks that look fierce but are often far gentler than their appearance suggests. These sharks are found in warm and temperate seas around the world, usually near the coast or around coral and rocky reefs. They’re easy to recognize by their pointed snouts, bulky bodies, and rows of long, sharp teeth that stick out even when their mouths are closed. This gives them a permanent “snarly grin,” which makes them look scarier than they really are. In truth, sand tiger sharks are generally calm and slow-moving and pose little threat to humans.

What makes the Carchariidae family especially unique is their behavior and reproduction. Unlike many other sharks that give birth to multiple pups at once, sand tiger sharks have a very unusual system called intrauterine cannibalism. This means that inside the mother’s womb, the first embryos to develop start eating their smaller siblings, so only one large, strong pup is born from each uterus. This “survival of the fittest” strategy ensures that the pups that are born are tough and ready for life in the ocean, but it also means sand tigers have very low reproductive rates compared to other sharks. This unusual reproductive method is one of the most distinctive traits of the family.

Another cool feature of these sharks is their ability to gulp air. Sand tiger sharks often come up near the surface, take in a gulp of air, and then hold it in their stomachs. This trick gives them neutral buoyancy, allowing them to hover almost motionlessly in the water without sinking or constantly swimming. It makes them look like ghostly figures gliding slowly through reefs, which is one reason divers find them so mesmerizing. Unlike faster, more active sharks like makos or hammerheads, sand tigers are built for stealth and patience, slowly stalking their prey of small fish, rays, and crustaceans before striking.