Although we usually think of milk as the lactose-containing fluid secreted by the mammary glands, scientists have discovered that it's not just mammals that "make milk," according to a report by Christina Salinsky at Discover Magazine. magazine).

There are many species that give their babies support by making their own milk-like substances.

These milk-like species are not only rich in nutrients, but some contain ingredients that help youngsters fight infection or build up the gut microbiome, just like mammalian milk, proof that the animal world still has many surprises.

1- the bathroom

Both female and male pigeons produce a white nutritious liquid from the food storage pouch in their throats (the crop), and their chicks only eat this “crop milk” for the first three days after hatching, then the adults begin to feed the young.

Although youngsters continue to receive crop milk until they are about 28 days old, - as is the case with mammalian milk - scientists have found that crop milk contains antibodies from parents, activates genes involved in the immune system, and contributes to the formation of a microbiome. The intestines, and the hormone that stimulates milk production in female mammals, called prolactin, is also what stimulates milk production in both male and female pigeons.

Both female and male pigeons produce a white nutrient fluid from the food storage bag in their throats (Shutterstock)

2- Imperial Penguin

For emperor penguins in Antarctica, it is the males that spend the harsh winter incubating the egg, and they also make a fatty liquid in their crops, and they regurgitate the milk of the crop to feed their young, while the females do not make milk, but bring food to youngsters instead.

3- Flamingo (pink flamingo)

The flamingo - male and female - also makes crop milk, and chews it in the mouths of its chicks for up to 6 months. The milk of the crop is characterized by a bright red color due to the presence of a red antioxidant called xanthaxanthin, which also helps to turn chicks from white to pink. While mother flamingos lose their pink color and become whiter during the breeding season due to providing nutrients to the chicks.

The flamingo - male and female - also makes crop milk, and chews it in the mouths of its chicks (Shutterstock)

4- Tsetse fly

The tsetse fly is a stinging insect that can spread a parasitic organism that causes sleeping sickness in humans. It is a fly that gives birth to its young, unlike most insects. The larva grows inside the uterus of a female “tsetse” fly, which contains glands that secrete a milk-like substance to support the larva. As with mammalian milk, the nutritional properties of this "milk" change as the larva grows.

5- Pacific cockroach looks like a beetle

Cockroach larvae, like the larva of the tsetse fly, grow inside their mothers' bodies, feeding on a liquid that scientists say is one of the most calorie-rich "milk" on the planet.

The larva grows inside the uterus of a female tsetse fly, which contains glands that secrete a milk-like substance (Shutterstock)

6- Jumping spiders

Female jumping spiders, which live in Southeast Asia, make a nutritious substance for their young, which they feed on to survive. The spiders wrap around their mother like a group of puppies to feed on this "milk", which contains four times more protein than cow's milk, and feeds them for a period of time. Approximately 20 days, then begin to hunt food on their own.

7- Thickness of the disc

Colorful Amazonian disc fish make milk-like mucus to feed their young, and both parents produce sticky mucus from their skin, which is not only rich in nutrients but also contains beneficial bacteria that colonize and establish the gut microbiome of the fry, which do not feed on anything else until 3 weeks old. Then the parents begin to swim away for longer and longer periods so the young fish can explore other foods, such as algae and small worms.

8- legless

Legless are tropical amphibians similar to large worms or sticky snakes, which give birth to some species and the young growing inside the mother eat the cells lining the uterine tube, but in other species of legless, the outer layer of the mother's skin turns into a nutrient-rich meal for the offspring, which flakes off to be eaten Young children have special teeth, and although it is not a liquid, it performs a similar function as milk.

9- Great White Sharks

The young of great white sharks grow inside the mother's womb, but because they do not have the umbilical cord to get nutrients like mammals, the uterus secretes a milky substance that the young feed on before birth, (some species of sharks have an umbilical cord).

Colorful Amazonian disc fish make milk-like mucus to feed their young (Shutterstock)

10- Roundworms

Roundworms are microscopic round worms that live in the soil, do not have a heart or blood, and their entire body contains only about a thousand cells (the human body contains about 30 trillion cells). However, in 2020, scientists discovered that one species of these roundworms, Caenorhabditis elegans, secretes a nutritious lipoprotein to help its offspring grow.