The fact and fallacy about Hippo pink blood, sweat, and milk

What is fact and what is fallacy about Hippo pink blood, sweat, and milk? What is pink and what is not?

The Common Hippopotamus (Hippopotamus amphibious) is a large, semi-aquatic African even-toed ungulate (hoofed) mammal in the Hippopotamidae family.

It has a grey-brown, hairless, barrel-shaped body, with pink patches, a big head, and small stumpy legs.  

The female Hippopotamus is pregnant for eight months before giving birth to one live young at at time, called a calf. The baby Hippo is born underwater, but swims quickly to the surface to take a breath of air.

Common Hippopotamus

The Safaris Africana website has an excellent article on the issue of hippo pink milk – Is it Really Pink?

The mother, like all mammals, produces milk to feed her calf. The milk is not pink – this is a fallacy. A fallacy is a belief that is not true. The milk is creamy white like the milk of other mammals (like the colour of cow’s milk). The Hippo calf feeds on its mother’s milk for about eight months, but it starts eating grass at three weeks of age.

Hippo blood is not pink either. This is a fallacy. 

Hippo sweat is not pink either. This is a fallacy.

The Hippo does secrete a liquid substance from its skin, which is often referred to as ‘blood sweat’ – but it is not blood, and it is not sweat. The liquid comes from its mucus glands, not from its sweat glands. In humans, most people will know that mucus comes out of our nostrils, but it is also found in other parts of the human body, such as the lungs and stomach. 

The Hippo’s skin secretion is a natural red-coloured substance. The liquid substance first comes out of the skin colourless, and then it becomes red-orange to brown within minutes due to a reaction with sunlight. 

The secretion has two pigmented (coloured) chemical acids: 1) red hipposudoric acid, and 2) orange norhipposudoric acid. 

The colours of the acids are not related to the food that the Hippo eats – all Hippos secrete these pigmented acids. 

There are two main purposes for the secretion: 1) to act as a sunscreen to absorb ultraviolet (UV) rays from the sun, and 2) to act as an antibiotic to slow the growth of disease-causing bacteria on its skin.  

Common Hippopotamus
Common Hippopotamus
Common Hippopotamus
Common Hippopotamus

Location of photographs: Kenya

Photographer: Martina Nicolls


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