BEIJING, Nov. 30 (Xinhua) -- Chinese scientists have discovered a species of spiders that can produce milk and care for their young, providing a new take on the understanding of invertebrate animals' maternal care.
The study, published online Thursday on the U.S. journal Science, was conducted by researchers from the Chinese Academy of Sciences (CAS).
The findings focus on Toxeus Magnus, a species of jumping spider native to southeastern Asia, which lives in nests and looks like ants.
According to the study, spider mothers in their laboratory-based nests were found to feed a milk-like substance to their spiderlings and continue to care for them as they matured.
During the first 20 days, the spider babies were found to first drink droplets of spider milk left on the surface of the nest and then suck directly from their mother's abdomen area.
Compared with cow's milk, spider milk has nearly four times the protein but less fat and sugar.
From about day 20 to day 40, the young spiders were able to leave the nest to hunt food, but they were still allowed to drink milk from their mothers.
The most intriguing part starts after 40 days when the spiders reach sexual maturity. Only daughters were allowed to stay with their mother in the nest, while the sons were attacked by the females and not allowed to return home.
In the study, maternal care and milk provisioning appeared to work together to ensure the long-term survival of young spiders.
Of the 187 spiderlings observed in 19 different nests, the survival rate was 76 percent for spiders that received both. Separated from the mother at day 20, the survival rate of the spiderlings dropped to 50 percent.
Previous studies show that maternal care, which continues after the offspring reach maturity, only exist among some long-lived advanced social vertebrates like humans and elephants.
Chen Zhanqi, lead author of the study from Xishuangbanna Tropical Botanical Garden, CAS, told Xinhua the findings demonstrate that mammal-like provisioning and parental care for sexually mature offspring also evolved in invertebrates.
He noted that the new findings encourage researchers to reevaluate this "parenting style" among animals, especially in invertebrates. Invertebrates make up over 95 percent of Earth's species.
Nicole Royle, a senior lecturer in the behavioral ecology of Exeter University in Britain, said it is the most comprehensive study that proves long-term maternal care also exists in invertebrates.
"It will help researchers gain a better understanding of the evolution process of milk provisioning and parental care for sexually mature offspring across the animal kingdom," he said.
