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How Do Whales Breastfeed Underwater?

On a recent whale watching trip, I asked one of the guides about how whales breastfeed underwater. His answer intrigued me, so I conducted some further research into this when I got back to shore.

Whales have inverted nipples inside mammary slits. When the calf is ready to feed, they dive underneath the mother and nudge the mammary slits. The nipple is released, and the mother feeds milk to the calf.

I found this really interesting and wanted to find out some more information. If you want to find out more, please read on.

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How Do Whales Breastfeed Underwater? 

Sea mammals have evolved and developed unique mechanisms that enable them to survive in their environments. In the case of the whale, they have their own mechanisms of breastfeeding underwater. Whales are surrounded by water, and breastfeeding in this kind of environment is not an easy occurrence.

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Do Whales Produce Milk?

Whales are sea mammals and possess the typical characteristics of all mammals. This means that they have mammary glands and produce milk to feed their young. 

Depending on the whale species, the calves require plenty of milk for them to grow and stay healthy. Generally, a young calf can consume milk that is approximately 10 percent of its body weight. The blue whale is the largest of the whale species. Females can produce over 200 liters of milk in a single day.

Do Whales Have Nipples?

Whales do have nipples, but they are not extended on the outside as in humans. Whales spend their entire life inside the water, so nipples and breasts outside would not be the best place.

Whale nipples are enclosed within folds of skin referred to as mammary slits. Whenever a calf wants to nurse, it nudges onto the mammary slits, which stimulates the mother to expose the nipples.

Find out how whales evolved in this article I wrote

Whales have inverted nipples. This is not the same as terrestrial mammals that have protruding nipples. When the calf is ready to feed, they dive underneath the mother and nudge the mammary slits.

This signals to the mother that the calf is ready to feed and works to stimulate the mammary slit to release the nipples.

After stimulation, the whale lets out the nipples from the mammary slits, and the young calf wraps its mouth around it. This ensures that the milk is channeled directly into the mouth. This ensures that none of the fluid is lost into the water. 

The baby whales roll their tongue into a tube or U-shape. The rolled tongue is then pressed onto the upper palate and placed around the nipple. The whale mother then ejects milk right into the mouth of the calf. The mammary glands have particular muscles that first contract, then shoot out milk directly into the mouth.

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Whale calf feeding

What is The Consistency of Whale Milk?

The whale milk has a very thick consistency. The milk is almost solid. The thickness is attributed to the high-fat concentration that can reach up to 50% fat in some whale species. The consistency and texture of the whale milk are compared to that of toothpaste. 

Whales produce large amounts of milk to sustain the survival of their young ones. The blue whale calf gains weight at a remarkable rate of 100 kgs in a single day. This means that it must suckle over 150 liters of milk a day. The liquid is also very rich in all the nutrients vital for the calf’s growth.

One of the main reasons whales can successfully breastfeed underwater is the milk’s consistency. Whale milk has an unusually high-fat content that ranges between 35% to 50% fat in many species.  

The high-fat content makes the milk thick enough to pass through the water. Baby whales do not have lips and therefore cannot possibly nourish the same way as land mammals. High-fat concentration in the milk is important because the adult female whale can eject liquid into the calf’s mouth without dissolving into the water around their lips.

There is evidence that sperm whales feed on milk orally rather than through suckling. The milk is released into the water, and the calves feed on the milk directly from the water. 

Sperm whales have mouths that may not be conveniently shaped to support suckling. Therefore, the only way for a young calf to feed on milk is in this manner.

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How Long do Whales Breastfeed?

There is only one breeding season for whales. The adult female whale mates with more than one male. This is to increase the chances of the female whale getting pregnant.

The female whales produce offspring every 1 to 5 years, although this depends largely on the species. The whales do not reproduce more often, which allows plenty of time for the calves to grow fully and increase their survival chances.

The lactation habits differ between baleen whales and the toothed whales. The baleen whales breastfeed their calves for a shorter period. The lactation period lasts between 5 to 7 months for baleen whales. During this time, the baleen whales fast, eating only small amounts of food.

Whale calf feeding

Toothed whales breastfeed for a longer period than the baleen whales. Their lactation period can last between 1 to 3 years. The mothers continue to feed in the usual way.

Breastfeeding in whales continues until the calf is old enough to survive on its own and hunt its own food. At six months old, baby whales are usually weaned but may continue to breastfeed. When weaning begins, the amount of milk produced gradually decreases.

Breastfeeding creates a close bond between a mother and her calf. There are times a calf will continue to suckle on the nipple even after lactation stops. Some species of whale have mother-child bonds that last a lifetime.

Whales often swim close to the shore. Find out why here

What is the Importance of Milk to the Young Whales? 

Similar to terrestrial mammals, milk is a vital part of a young whale’s existence. Baby whales rely on milk for healthy growth and nourishment. Newborn whales survive entirely on milk until they are ready for weaning.

Without milk, baby whales would have low survival rates and starve to death. Typically, a newly born whale consumes large amounts of milk in a day. The milk is their sole source of food at this time.

Whale milk is rich in all the nutrients required for the calf to grow well and thrive. The liquid is packed with healthy fats that provide energy for the rapidly growing calf. Other nutrients in the milk support bone development, boost the immune system and ensure the brain’s proper functions.

Suckling milk creates an unbreakable bond between the mother and her calf. This is important in the development of the baby whale. Research has proved that the relationship between marine mammals and their parents is crucial for their survival.

Marine mammals living in captivity have a shorter lifespan than their counterparts in the wild. It is believed this is due to their inability to nurture naturally.

Do whales drink seawater?  Find out in this article I wrote

Whale milk contains a high concentration of fatty acids. The fat in milk plays a significant role in the development of blubber. Blubber is a thick layer of fat under the skin of marine mammals, such as whales.

Blubber develops as a whale grows. Since whales spend so much time underwater, they need a mechanism to keep their body temperatures constant and prevent excess heat loss. 

Blubber acts like an insulating layer against the cold from the water. The high-fat content from the milk enables the thick insulating fat layer to develop.

Many marine mammals survive cold conditions using a layer of fat.  Find out more about blubber in this article I wrote

Do Whales Feed Other Calves?

The emotional and social relationship that exists between whales and their calves is often unique. It is not common to find a female whale breastfeeding a calf other than her own.

However, some family groups are so close that they share the responsibility of taking care of the young ones. In such pods, a female whale can breastfeed a calf belonging to another whale. This only occurs in some whale species.

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Recommended Books

Guide to whale watching in North America : USA, Canada, Mexico. Where to go, what to see.

Handbook of Whales, Dolphins and Porpoises Of the World

Encyclopedia of Whales, Dolphins and Porpoises


Carwardine, M. (2017). Mark Carwardine’s guide to whale watching in North America : USA, Canada, Mexico, where to go, what to see. London: Bloomsbury.

Carwardine, M. (2010). Whales, dolphins and porpoises. London: Dorling Kindersley.

Bernhard Grzimek, Schlager, N., Olendorf, D. and American (2003). Grzimek’s animal life encyclopedia. Detroit: Gale.

Hadoram Shirihai, Jarrett, B., Graeme Cresswell and Kirwan, G.M. (2019). Whales, dolphins and seals : a field guide to the marine mammals of the world. London: Bloomsbury Wildlife.

Martin, T. (1990). The illustrated encyclopedia of whales and dolphins. Hodder.

Nowak, R.M. and Walker, E.P. (1991). Walker’s mammals of the world. Baltimore: Johns Hopkins University Press.

Perrin, W.F., Würsig, B.G. and J  G  M Thewissen (2002). Encyclopedia of marine mammals. San Diego: Academic Press.

Richard John Harrison and Bryden, M.M. (1990). Whales, dolphins and porpoises. London: Merehurst.

Williams, H. (1988). Whale nation. London: Cape.

Wilson, D.E. (1999). The Smithsonian book of North American mammals. Washington: Smithsonian Inst. Press.

May, J. (1990). The Greenpeace book of dolphins. London: Century.