It is not just human mothers who are nurse their children; some utterly unpredicted animals do that too. We know the importance of milk for infants. It is a rich mixture of nutrients and protective chemicals that is necessary for the growth of an infant. Only one particular group of animals produce milk for their youth in the animal kingdom: mammals, the group to which we belong. Mammalian milk is known as true milk.
However, a few other animals produce secretions that strongly resemble milk for their babies. Some animals that produce milk are as follows:
Mammals may have a milk monopoly, but some birds, such as pigeons, also produce a milk-like substance for their babies. Pigeons are great to share parental responsibilities. Unlike mammals, male and female pigeons produce a milky substance to feed their young squabs. The pigeon parents produce ‘crop milk,’ which is secreted at the base of their throats into a small sac that usually stores and moistens food. If a squab is born, the pigeons keep repeating the crop milk into the baby bird’s mouth.
Some cockroaches feed a kind of milk on their young ones. The Pacific beetle cockroach is one such example. It is impressive yet bizarre, but Pacific beetle cockroach can make crystallized “milk,” which has a reliable protein content with essential fats, sugars, and amino acids. The production of milk happens because they give birth to young ones instead of laying-eggs.
Like the Pacific beetle cockroaches, female pseudoscorpions produce a substance similar to milk. But she secretes it from her ovaries rather than her womb. In a bag-like structure attached to her belly, the female carries her fertilized eggs. After the infant pseudoscorpions have hatched, they remain in the sac and feed on ovarian milk from their mother. Pseudoscorpions are 2-3 mm long. These are sometimes found in dusty book spaces, and are often called “book scorpions.”
- Discus Fish
Few fish are renowned for their ability to parent. The majority of the fish leave their young at hatching, but not the discus fish. The discus fish “milk” doesn’t seem milky at all. Their milk is a mucus-based secretion, which coats both parents’ bodies. These milk-giving animals produce milk, which is rich in proteins and antibodies.
- Taita African caecilian
The Taita African caecilian has developed a more elaborate parenting style from southeast Kenya. Rather than providing milk as mammals do, or catching prey and taking it back to the nest as birds do, the Kenyan species the female caecilians allow their young ones to scrape away and eat a layer of the skin.
Some of the animals that produce milk are discussed above. Their milk is known as “false milk,” they don’t look like a cow or human milk, nor are they produced in the same way. But it does serve the same purpose: it feeds babies of the animals until they are old enough to fend for themselves.