Lunch and Teeth Sharks sometimes eat their own kind. And eat seals, dead whales and many others. why do you see blood on the sharks teeth?Its because all the things it has eaten.the great white sharks tooth is about 3 inches long. A tiger shark will practically eat anything in the ocean floor.And big sharks like a great white wont bite humans unless the humans harm the shark. a sharks tooth is not the strongest in the sea, a piranas tooth is sometimes stronger.