1, spiral toothed shark. The lower jaw looks more like a spiral snail shell than anything related to sharks. It was first unearthed in the Ural Mountains in 1800, belonging to an extinct species, living about 270 million years ago. Sharks grow to 7.6 meters long, and no upper teeth interfere with the arrangement of teeth.

2. Eagle shark. 93 million years ago, it lived on an ancient waterway and now covers part of Mexico. Shark fins extend 65,438+0.9 meters, making them wider than their length (65,438+0.65 meters). Although the teeth of these sharks did not survive in fossils, their discoverers suspected that they were filter-feeding animals like modern whale sharks.

3. Ninja lantern shark. The ninja lantern shark was inspired by the great white shark. The same names of these invisible sharks are thought to be cousins of the scientists who discovered this creature. The smooth black skin and gentle bioluminescence of this shark are used to mix with sunlight filtered from the ocean surface, reminding them of "super ninja".

4. Inflated sharks. A big shark can swallow water and then double its size. Even sharks need to avoid predators. The big sharks hiding in the crevices of rocks all day have devised a clever plan to defeat potential predators: they absorb a lot of seawater and expand to twice their normal size.

5. Ghost sharks. Sliding in the dark ocean about 1640 meters deep looks like a strange, silent ghost. For this reason, these elusive sharks are sometimes called "ghost sharks". The strangeness of this species lies in the spiny rod-shaped organs on the male head. This organ is used to locate females during mating.