how do whales drink milk underwater?

Whales have inverted nipples inside mammary slits which enables them to suckle and drink milk while underwater.

The mammary slits that the whales posses are not your typical “slit” as it is more of an opening than just a simple hole. The opening sticks out in front of their stomach with a thickened membrane near the underside, which is actually quite similar to how some female humans also produce milk after giving birth. This bottom-layered membrane seals around a liquid (like water or other liquids) before the whale begins its journey into hunting for food for their family – they keep it tightly sealed so that no liquid escapes through their anus and can take in everything much easier.