ABOVE: ZHANQI CHEN
When the 18th-century biologist Carl Linnaeus classified a group of animals as “mammals,” he based the name on one key characteristic—mammary glands, from which females produce milk to feed their young. While lactation is a common feature among mammals, it turns out that it isn’t unique. Scientists have since learned that some nonmammalian creatures also make milk to feed their young. Cockroaches, for example, nourish their developing embryos with a milky, protein-rich fluid. And a new study, published today in Science, reveals that at least one other invertebrate species, the ant-like jumping spider Toxeus magnus also produces milk to feed its young.
“There are not very many cases of feeding with secretions like this outside of mammals,” says James Gilbert, a zoologist at the University of Hull who was not involved in this work. “Invertebrates never fail to amaze you.”
Zhanqi Chen, a postdoc at the Chinese ...
