A Hippopotamus (Hippopotamus amphibius) half-submersed in water with Common Water Hyacinth (Eichhornia crassipes) on its head. Hippos are territorial and will keep a close eye on potential intruders. This Hippo came up for a look as I stood on the bank. Many water ways and bodies in Southern Africa have been clogged by the alien and invasive Common Water Hyacinth.