Pygmy hippopotamus unusual secretion as common hippos, that gives a pinkish tinge to their bodies, and is sometimes described as "blood sweat" though the secretion is neither sweat nor blood. This substance, hipposudoric acid, is believed to have antiseptic and sunscreening properties. The skin of hippos dries out quickly and cracks, which is why both species spend so much time in water. The skeleton of "C. liberiensis" is more gracile than that of the common hippopotamus, meaning their bones are proportionally thinner. The common hippo's spine is parallel with the ground; the pygmy hippo's back slopes forward, a likely adaptation to pass
Common species species. Common species are frequently regarded as being at low risk of extinction simply because they exist in large numbers, and hence their conservation status is often overlooked. While this is broadly logical, there are several cases of once common species being driven to extinction such as the passenger pigeon and the Rocky Mountain locust, which numbered in the billions and trillions respectively before their demise. Moreover, a small proportional decline in a common species results in the loss of a large number of individuals, and the contribution to ecosystem function that those individuals represented. A recent paper argued that