Hippos are considered the most dangerous because they are aggressive, they will attack a boat and turn it over. The don't eat people but they are extremely dangerous due to their size. In Africa, the saying goes 'in the bush, an elephant can kill you, a leopard can kill you, and a black mamba can kill you.
Definition: Job Enrichment is the addition to a job of tasks that increase the amount of employee control or responsibility. It is a vertical expansion of the job as opposed to the horizontal expansion of a job, which is called job enlargement.
Environmental enrichment is the intentional manipulation of captive animals surroundings to affect its physical and mental well being in a positive way. This relatively new approach to animal husbandry has been gaining momentum in the zoological field, but has the potential to affect the lives of all captive animals.