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Today on Animal Fact Files we’re discussing lantern sharks. There are more than 50 classified lantern shark species and they make up more than 10% of all the shark species alive today. These deep sea dwelling fish get their common name because they produce light! They're bioluminescent, and they're one of only two known shark families to do this. Lantern sharks may light up for a number of reasons. First, it could be a way to hide themselves in the water column.

Lantern sharks live where little to no light penetrates through the ocean. They have light producing organs along their belly or sides. These light up bluish-green in color to make the sharks appear invisible when looking at them from below in deeper waters. This helps lantern sharks avoid predators. Lantern sharks are known as some of the smallest sharks in the world. Technically, it's not known with certainty which shark is the smallest because new shark species, including lantern shark species, are described almost yearly! However, the smallest lantern sharks max out at less than eight inches (20cm) in length as adults! That's small enough to fit in an adult human's hand! Their small size makes them easy prey for other sharks like kitefin sharks and frilled sharks. Still, not all lantern sharks are this small. The larger species reach about three and a half feet (107cm) in length as adults. Plus, these sharks come equipped with spines to ward off any threats.

Lantern sharks have no anal fins and two dorsal fins with the second dorsal fin often appearing larger than the first. In front of each of these fins is a sharp spine the lantern shark can use to stab an attacker. The spines don't contain venom, but some lantern shark species have light emitting organs around them as a warning. Like a sea slug's bright colors, this is aposematic in nature. Animals in the deep sea generally produce light for one of three reasons: to blend in with their surroundings - as previously mentioned, this lighting is often along the animal's underside; they produce light to communicate with other species - this light is usually dorsally located and warns about sharp spines, or, like an anglerfish, lures prey in; and they also produce light to communicate with members of their own species. Lantern sharks are believed to do all three! Some lantern shark species form large groups. To find each other in the abyss, they communicate with light.

These sharks live from a few hundred feet below the waves to over half a mile (800m) into the ocean's depths. Lantern sharks live in deep tropical and temperate waters around the world, swimming along the sea's bottom on continental slopes and underwater mountains. Some species also swim in the open ocean. For this reason, they're largely understudied. Their exact methods of reproduction are unknown, but it's believed that females retain their eggs until the babies hatch inside and she gives birth to live young. Depending on the female's size, she may have two to twenty pups. The pups in the smallest species barely reach two inches (5cm) in length when they're born! Even panda babies, who are notoriously small when born, are bigger than most lantern shark pups! It's unknown how long these fish live.

Though they have spines and teeth, lantern sharks aren't considered harmful to humans. First of all, they rarely come in contact with people. Their greatest exposure to us occurs when they're accidentally caught in fishing operations. Second, most species are so tiny, they could be held in one hand! Third, they're not after us anyway. Lantern sharks eat sea squirts, crustaceans, worms, cephalopods, and the occasional fish to fill their bellies.

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