Another creature which hippos play host to is the Oculotrema hippopotami, a parasitic fluke, found on 90 percent of all hippos' eyes. In the water, certain fish species eat algae and other deposits off the hippos' skin. Woodland Park Zoo has two female hippopotamuses which can be viewed in the African Savanna, usually sleeping in their pool. The hippo pool is cleaned twice a week and the animals love to play in it while the water is filling up. Other animals which can be viewed in the African Savanna are the reticulated giraffes and African lions.
Hippopotamuses are a vulnerable species.
The primary reason hippos are vulnerable is because they have been hunted excessively for their meat, fat, ivory teeth and hides. Unlike elephant tusks, hippo teeth do not yellow with age. This makes hippo ivory more desirable on the black market. Also, hippos have been hunted for sport because they damage cultivated fields by trampling and eating crops or because they are very dangerous to humans. The last of the wild hippos are compressed unnaturally into remaining suitable habitats.