how many teeth does a zebra shark have
Zebra shark The zebra shark has a cylindrical body with a large, slightly flattened head and a short, blunt snout. The eyes are small and placed on the sides of the head; the spiracles are located behind them and are as large or larger. The last 3 of the 5 short gill slits are situated over the pectoral fin bases, and the fourth and fifth slits are much closer together than the others. Each nostril has a short barbel and a groove running from it to the mouth.[8] The mouth is nearly straight, with three lobes on the lower lip and furrows at the corners. There are 28–33 tooth rows in the upper jaw and 22–32 tooth rows in the lower jaw; each tooth has a large central cusp flanked by two smaller ones.[3]
Zebra mussel The zebra mussel (Dreissena polymorpha) is a small freshwater mussel. This species was originally native to the lakes of southern Russia and Ukraine,[2] being first described in 1769 by the German zoologist Peter Simon Pallas in the Ural, Volga, and Dnieper rivers.[3] However, the zebra mussel has been accidentally introduced to numerous other areas, and has become an invasive species in many different countries worldwide. Since the 1980s, they have invaded the Great Lakes and the Hudson River. They are commonly found on the bottom of ships and eat the algae that is food for fish. Inspectors check ships for the mussels before they leave port. Scientists are trying to control the mussels.