Toxeus Magnus breastfeeds its young. It produces a very rich substance in protein – and very similar to milk.
Chinese scientists have discovered that at least one species of spider suckles its young, much like mammals, and with a rich protein substance – very similar to milk.
As researcher Zhanqi Chen of the Xishuangbanna Tropical Botanical Garden and one of the authors of scientific research – published on Thursday (29) by the journal “Science”, explained to BBC News Brasil, the discovery of the spider that breastfeeds occurred because of a behavior that intrigued scientists.
The fact that, in the species of jumping spider Toxeus Magnus, puppies tend to stay longer in the same nest as the mother, even when they grow up. “This is unusual in jumping spiders,” says Chen.
“So we hypothesized that the mother could provide long-term maternal care,” he continues. The question then became: if they do it, how do they do it? And for how long?
Armed with such questions, the researchers went to the observation. They found that the Toxeus Magnus pups do not leave the nest until the third week of age.
At this point in life, the bugs are already 3.5 millimeters long – these spiders, much like ants, are born with 0.9 millimeters.
“On the other hand, in all this time, the mother has never been observed bringing food (like fruit flies) to the nest,” reports the researcher. “That left us confused about what the offspring’s food source would be.”
Chen said that the team then formulated three possibilities – according to what usually happens in the animal kingdom.
The feeding could be provided by regurgitation, by the mother. Or the spider chicks could eat trophic eggs – unfertilized eggs that are put just for food, as for instance with bees and ants, for example.
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Or even fecal feeding. “However, the observation record rejected all these hypotheses,” says the scientist.
This interrogation was literally taking Chen’s sleep.
He told the story that it was at dawn – around 1:30 a.m. on July 2017 – that he noticed something very interesting.
One of the pups grew in size just as it was attached to the mother’s abdomen. “It was a very similar behavior to breastfeeding in mammals,” he says.
Aware of this phenomenon, the scientist began to focus his analysis on the mysterious fluid that served as food for the offspring. He realized that as soon as they were born, the spiders first ingested droplets of the same liquid already deposited on the surface of the nest.
Only later were they able to suck on the mother – by the same hole used for egg laying.
This feeding, the researchers found, is the main source of nutrients for the pups until they reach about 40 days of life, ie practically when they reach sexual maturity.
The fluid was also analyzed in the laboratory. According to Chen, this substance is very similar to milk and contains almost four times the amount of protein found in cow’s milk.
What causes doubt: will one day this substance be used industrially?
“Theoretically, this is all possible, but I think we are still a long way from discussing this. We need to wait until all the components of the spider milk are clearly analyzed,” says Chen.
“Maybe someday in the future, we might start having spider milk industries by some biotechnical methods.”
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The researchers involved also highlight the importance that the discovery may have on the understanding of parental care in nature. After all, it has always been believed that caring for offspring until practically adulthood were the most common characteristics among mammals.
In the case of Toxeus Magnus individuals, Chen and his team observed that the mother not only feeds the pups but also helps in protection and other survival care.
According to the latest issue of the “World Spider Catalog,” a taxonomic compendium with 47,868 recorded species, the Toxeus Magnus is an arachnid identified and first described in 1933. It is a native spider from Taiwan.
Administered by the Chinese Academy of Sciences, the Xishuangbanna Tropical Botanical Garden, where spider milk was discovered, has been an institution since 1959.
It is a specialized research center, where about 340 scientists work. The Botanical Garden has more than 13 thousand species of plants and animals.