In one of Rabbi Noach Weinberg's taped lectures, he was onced ask why the Hippo is not a Kashrut Rule Breaker, because it was claimed it has the necessary cloven hoof and it is not a pig. He answered, that the Hippo was a type of pig because scientists classify it with the pig family.
In light of recent research, where I came across the fact that due to genetic analysis, scientist now hold that hippos are more closer to whales and dolphins than pigs, I looked around the internet for a better answer.
This is a quote from the Chicago Rabbinical Council. Their science info is based on Rabbi Dr. Ari Zivotofsky, professor at Bar Ilan University and an expert on the kashrus of animals and birds, who in turn consulted with his brother, Dr. Doni Zivotofsky, D.V.M.,
http://www.crcweb.org/faq/faqanswer.php?faqid=129Rather, it seems that the answer to your question is that the hippopotamus does not have cloven hooves. A hippo has four toes which are covered and connected by thick skin which in turn produce a web-effect and aids the hippo in swimming. Thus, a hippopotamus is much like most non-kosher animals which do not chew their cud and do not have split hooves.
[A related side note from R’ Zivotofsky regarding the hippopotamus’ ruminant status: Without exception, every animal with a 4 chambered stomach is a ruminant. There are those who dispute this and assert that the hippo is an example of an animal that has 4 chambers and is not a ruminant., but this is erroneous. In fact, it has a three chambered stomach: parietal blind sac, the stomach (which can be considered simply connecting tissue) and the glandular stomach. For more on this see: E.T. Clemens and G.M.O. Maloiy, “The digestive physiology of three East African herbivores: the elephant, rhinoceros and hippopotamus”, Journal of Zoology, 1982, Vol. 198, pp 141-156.]
Topic: The Hippopotamus is not a Kashrut Rule Breaker (Read 4508 times)