How Do Spiders Rake Their Young?

It’s not surprising that spiders are a little mammalian. They have long been known to regurgitate a liquid that looks like milk, and to care for their young. But are spiders actually capable of raising their young?

According to a recent study published in the journal Nature, some spiders do it. They produce a “milk” that is more than four times the protein content of cow’s milk. And they do it continuously, from birth to subadult ages.

The milk-like fluid is secreted by the female Toxeus magnus, a ant-mimicking spider. It is deposited on the inside lining of the nest and is given to the young.

It looks similar to mammary fluid and contains fat and four times the protein of cow’s milk. But it is also derived from digested nutrients in other tissues of the abdomen. The fluid is not a true milk because the Toxeus magnus spider does not have mammary glands.

In the wild, spiders often contain grown juveniles. However, they do not form colonies. Their young can remain in the nest for 20 days. But if the mother is removed, the younger offspring die off, making them more susceptible to predators in the wild.

Some spiders also lay eggs that function as food for their offspring. Some species of spiders lay more than 600 eggs in one sac. Moreover, many spiders can lay an egg in a continuous stream.

The female spider fertilizes the eggs with her sperm and guides the young to a food source. The young then suck the milk from the epigastric furrow of their mother. They continue to supplement their diet with the mother’s milk for another 20 days.