The large ant spider has a groin in its abdomen that secretes fluid to feed the juveniles
On November 30, 2018, the journal Science published a study results, China's Xishuangbanna Botanical Garden Quan Ruichang and Chen Zhanqi team said that found that a certain organ of the large ant spider can secrete milk, and will continue to breastfeed juvenile spiders for at least 40 days, and the nutritional value of its milk is still quite high. This act of breastfeeding, along with the long-term care of offspring, refreshes our traditional impression of invertebrates.
The giant ant spider has a population distribution in most tropical and subtropical areas of china, and if you pay a little attention, you can observe this wonderful small animal in the wild. As soon as the news about the large ant spider can breastfeed the juvenile spider came out, some spider breeders also deliberately captured a few self-rearing and observation in the wild.
Juvenile spiders are weaned for 40 days and left the nest for 60 days
The great ant spider is an arthropod of the genus Ants of the family Pterophoridae, resembling a large ant, with a body size of more than 11 cm, a black body color, a large eosno, a wide head and thorax back plate, a round abdomen, a waist hammer between the chest and abdomen, a generally rounded abdomen, black feet, and transparent basal segments. Female spiders have long tentacles, a wider jaw, and a slightly expanded end, resembling a male spider, but the male has a narrow and long jaw and a short gray-white hair on the back of the body. They usually inhabit fields and forests, weave nets on leaves, and feed on small arthropods and lepidopteran insects.
Ant spiders are timid and their whereabouts are hidden, and humans have not studied them much. The nest of the big ant spider is even more closed and secretive, and it is usually difficult to see. This time the researchers observed that the large ant spider has a lactation function, which was inadvertently discovered during the breeding process through artificial breeding.
Researchers have found that large ant spiders can not only produce milk, but also take care of young spiders step by step until adulthood. This phenomenon is rare in invertebrates, and no similar habit has been found in other spiders.
The paper describes: In the first 7 days of the hatching of the baby spider, the mother of the big ant spider will secrete milk to all parts of the nest for the baby spider to eat; after 7 days, the female spider will no longer actively secrete milk, but the baby spider will climb to the mother's reproductive groove to find milk; starting 20 days after birth, the baby spider will learn to leave the nest to find food, but they are not completely "weaned", and will still eat "complementary food" to the mother spider like "infancy"; by 40 days after the birth of the baby spider, it is close to adulthood. They are completely fed by going out on their own to hunt. At this time, the juvenile spiders are close to 4/5 of the size of the mother's body, but even if they are completely "weaned", in the next 20 days, they will still leave the nest during the day to find food, and return to the nest at night for the night. That is, the baby spider does not fully reach adulthood until 60 days after birth, and leaves home to live alone.
Ant spider family will "prefer women to men"
The researchers looked closely in the lab and found that the female large ant spider has a reproductive groove in its abdomen and secretes a milk-like liquid that is used to breastfeed the larvae.
In further analysis of this liquid, the researchers found that the main components in the milk of the spider are protein, fat and sugar. Compared with milk, the content of fat and sugar will be slightly lower, but the protein content is four times that of milk, and the nutritional value is quite high.
And scientists have found that the care of the mother of the big ant spider for the baby spider can be described as "meticulous", not only "feeding", but also regularly "deworming" her nest. For juvenile spiders, the "feeding" behavior of the mother spider is also the key to ensuring its healthy growth. The researchers found that if the baby spider does not drink "breast milk" at all, it may all die within ten days or so after hatching; in the "complementary food" period of 20-40 days old, the proportion of breastfed larvae is also higher than that of unhyered larvae.
What is even more interesting is that the large ant spider family has the phenomenon of "preference for women over men" - after the juvenile spiders become adults, the female spiders will actively expel the adult male individuals from the nest, so the number of female spiders left in the nest will usually be significantly higher than the male spiders. The researchers speculate that this phenomenon is presumably so that more offspring can be produced to grow the family.
The feeding behavior of the giant ant spider has forced scientists to rethink the evolutionary origin, evolutionary history and significance of the phenomenon of breastfeeding. Perhaps there are more invertebrate "mammals" waiting to be discovered.