Why this spider feeds its babies ‘milk’

Researchers have found that this fluid contains proteins, fats, and sugars—much like mammalian milk. It is produced from the spider’s reproductive system, and the young actively consume it by staying close to the mother.

What’s even more unusual is that this care doesn’t end quickly. The spiderlings continue to remain around the mother, returning to her for nourishment and protection as they grow, for at least 38-40 days. In fact, female offspring may continue to return for lactation even until sexual maturity. This kind of extended parental care is extremely rare in spiders, where most species rely on numbers rather than nurturing.

From a survival perspective, the strategy makes sense. By investing more energy into fewer offspring, the mother increases their chances of surviving in unpredictable environments. Instead of leaving survival to luck, she gives her young a stronger start.

The discovery of this behaviour has also changed how scientists think about “milk” in the animal kingdom. While this fluid isn’t identical to mammalian milk, it serves a very similar purpose—direct nourishment from parent to offspring during early development. Interestingly, this spider milk has roughly four times higher protein concentration than cow’s milk, along with fats and sugars.

So the next time you are afraid of a jumping spider, don’t forget to consider that she might be a loving mother afterall!