Carcharias

Once, this genus had several species, but many are now extinct, leaving the sand tiger as its sole modern survivor. Found in warm and temperate seas across the globe, Carcharias sharks are immediately recognizable by their menacing appearance: bulky bodies, pointed snouts, and rows of long, needle-like teeth that stick out even when the mouth is closed. This permanent “toothy grin” makes them look like villains straight out of a shark movie, but in reality, they are generally slow, calm, and not aggressive toward humans.

Unlike sleek, fast hunters like makos or hammerheads, sand tigers are hovering predators. They gulp air at the water’s surface and store it in their stomachs, which gives them near-perfect buoyancy. This allows them to float motionlessly in the water like ghostly shadows, conserving energy until they’re ready to ambush prey. They usually feed on small schooling fish, squid, and crustaceans, swallowing them whole with their sharp, slender teeth. Instead of chasing prey with speed, Carcharias sharks rely on stealth and patience—a very different strategy compared to many of their shark relatives.

One of the most extraordinary traits of Carcharias is its reproductive strategy, which is unlike almost any other shark. Females have two uteri, and although multiple embryos may begin to develop in each, only one survives in each side. This is due to a process called intrauterine cannibalism, where the strongest embryo consumes its siblings before birth. As gruesome as it sounds, it ensures that the surviving pups are large, well-developed, and capable of fending for themselves immediately after birth. This “survival of the fittest before birth” approach is rare in the animal kingdom and is one of the main reasons Carcharias reproduces so slowly.