Can Spiders Produce Milk?
WouterWhether or not spiders can produce milk has long been an enigma. Until now, there had been no clear explanation. But, recently, researchers from the Chinese Academy of Sciences in Yunnan revealed a new discovery.
The discovery suggests that female spiders have developed a milk-making ability to help them survive under harsh living conditions. They may also have evolved to protect their young from predators.
Female spiders secrete milk-like fluid into an epigastric furrow. They deposit the fluid around their nests. This provides a food source for the young. After the young begin to forage, they continue to take advantage of the milk until they reach sexual maturity.
A follow-up study showed that spiderlings that receive milk for the first 20 days of life had a higher survival rate. Spiderlings that lose their milk after this period also show a poorer survival rate.
Spiders don’t produce actual milk, but their milk-like liquid contains four times the protein and fat of cow’s milk. Some animals, including cockroaches, earwigs, and pigeons, have also been found to produce milk-like secretions.
In addition to their milk-making abilities, spiders provide a high level of maternal care to their offspring. Mothers nurse their juveniles against their bodies and regurgitate predigested food for their young. They also prevent inbreeding between siblings.
However, the intensity of spider maternal care has been considered unusual. It is believed that this type of maternal care is only observed in long-lived social vertebrates.
