In celebration of our new film Great White Shark, now playing daily in 3D and IMAX, here are some spectacular shark facts:
- Sharks began evolving about 450 million years ago. Of the roughly 340 living species some have changed little in the past 100 million years.
- Sharks were the first vertebrates to develop an immune system and may have a greater immunity to cancer than humans.
- Shark teeth are made of hard enamel, which may explain why ancient shark teeth are the most commonly found vertebrate fossils today.
- Some living shark species replace old and broken teeth as frequently as every ten days. There are 12,000 bull-shark fossil teeth on view in the Museum’s Hall of Vertebrate Origins—approximately the number of teeth a bull-shark will have during its lifetime.
- Shark bones are made of light, tough cartilage, which is rarely fossilized.
- Like other cartilaginous fishes, sharks do not have a gas bladder to keep them afloat so many species (but not all) must move constantly to keep from sinking. Many sharks have large, oil-filled livers that make them more buoyant.
- Most sharks bear live young. Some species can remain pregnant for over two years, longer than any other vertebrate.
- Sharks typically bear three to 12 pups and many do not reproduce until age 30, making it hard for them to recover when large numbers are killed by humans.