People often think hippos are herbivores with big smiling faces. Every now and then, reports of a hippopotamus (Hippopotamus amphibius) hunting down prey, eating a carcass, or stealing prey from a crocodile are heard, but they’re typically considered ‘aberrant’ or ‘unusual’ behaviour.
Now, however, a collaboration among researchers from 4 continents demonstrates that carnivory, or eating meat, is not uncommon among hippos at all, and that this behaviour may increase their susceptibility to mass mortality during anthrax outbreaks. Hippos, elephants, buffalo or antelope are often affected by anthrax epidemics, but anthrax outbreaks among hippos exhibit certain unusual characteristics that could be explained by consumption of the carcasses of infected animals — especially those of other hippos. The study findings are first published online on 6 December in the journal Mammal Review.
“The phenomenon of carnivory by hippos is crucial to an understanding of their susceptibility to this disease,” said Joseph Dudley, co-author of the study.
Toothed whales (Odontoceti), as a whole, mostly feed on fish and cephalopods, and then followed by crustaceans and bivalves. All species are generalist and opportunistic feeders. Baleen whales (Mysticeti), as a whole, mostly feed on krill and plankton, followed by crustaceans and other invertebrates. A few are specialists. Examples include the blue whale, which eats almost exclusively krill, the minke whale, which eats mainly schooling fish, the sperm whale, which specialize on squid, and the grey whale which feed on bottom-dwelling invertebrates. The elaborate baleen “teeth” of filter-feeding species, the mysticetes, allow them to remove water before they swallow their planktonic food by using the teeth as a sieve. Usually whales hunt solitarily, but they do sometimes hunt cooperatively in small groups. The former behaviour is typical when hunting non-schooling fish, slow-moving or immobile invertebrates or endothermic prey. When large amounts of prey are available, whales such as certain baleen whales hunt cooperatively in small groups. Some cetaceans may forage with other kinds of animals, such as other species of whales or certain species of pinnipeds.
(Source: Wiley press release, 07.12.2015; Wikipedia; UC Berkeley press release, 24.01.2005)