Do whales produce milk?

The need for milk is an essential part of the development of any young mammal, and being aquatic makes breastfeeding considerably harder. Nursing their young with milk is one of the things that defines mammals, so whales definitely do have mammary glands and they do produce milk. But how do they manage to breastfeed underwater?

Humpback Whale (Megaptera novaeangliae) mother and calf in Polynesia
This humpback whale mother will be producing lots of rich fatty milk for her calf. © Philippe Bourseiller/Getty

Do whales have nipples?

Species from three orders – Carnivora (including seals and sea lions), Cetacea (dolphins and whales) and Sirenia (manatees and dugongs) – live and feed at sea, but they've evolved different methods for breastfeeding.

Seals and sea lions have retractable nipples that tuck inside the body when the baby is not feeding, but animals that are fully restricted to the sea, such as whales and dolphins, have evolved ‘mammary slits’ – special folds of skin that enclose the feeding glands.

We're still not completely sure how they do it, but it is thought that either the calves can curl their tongues to channel released milk, or that specialised muscles actually contract the mammary glands, squeezing milk into the baby’s mouth.

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Blue whale mother and calf (Balaenoptera musculus). Aerial view of surfacing pair. Sea of Cortez (Gulf of California), Baja California, Mexico (Pacific coast)
Blue whale milk is some of the richest milk in the world. And there's plenty of it! © Mark Carwardine/Getty

What is whale milk like?

As a general rule, whale milk is rich in fats and comes in very large quantities!

The blue whale has the largest mammary glands on Earth – each is about 1.5m long and weighs as much as a baby elephant. Blue whale mothers can produce 200 litres of milk per day with a fat content of 35-50%. That enables a blue whale calf to gain weight at the incredible rate of 100kg per day!

Did you know that whale mothers communicate with their calves by 'whispering'?

Find out more here!

Photo © Fabrice Guerin/Getty

Humpback whale (Megaptera novaeangliae) mother and calf, Kingdom of Tonga"


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Ben Garrod is a Professor of Evolutionary Biology and Science Engagement at the University of East Anglia, in Norwich. Ben is also a television presenter, author and great ape conservationist.