Much like baby mammals nursing at the teats of their mothers, some baby jumping spiderlings are entirely dependent on nutritious spider milk secreted and fed to them by their mothers. What’s more, spider mothers continue to care for and feed their offspring the nutritious milk-like fluid – which contains nearly four times the protein of cow’s milk – into their subadult lives and long after they’re able to forage on their own, a recent study finds.
According to the results, this newly identified and peculiar behavior compares both functionally and behaviorally to lactation in mammals and hints to the possibility that long-term, milk-provisioning maternal care may be more common in the animal kingdom than previously believed.
Toxeus magnus is a species of ant-mimicking jumping spider. Laboratory observations show the young spiderlings first drinking from droplets deposited on the nest’s surface and then directly sucking from the mother’s egg-laying opening. According to Chen et al., spiderlings remained in the nest and nursed on spider milk for nearly 40 days, shortly before reaching sexual maturity. Furthermore, the authors found that while nursing was not critical to offspring’s survival after becoming independent, their mother’s presence during their young lives greatly assured their overall health and adult survival. The mothers’ nursing and care also seemed important for maintaining numbers of adult female offspring required for optimal reproductive success of the spider; although the mothers treated all juveniles the same, only daughters were allowed to return to the breeding nest after sexual maturity, the authors observed.
If, like me, you suddenly wondered “how far does a jumping spider jump,” here’s an answer. The largest of the jumping spiders at 25 mm (about an inch), Hyllus gigantus can jump four times its body-length, or the equivalent of a human jumping the length of a school bus. Here’s a 2:52 video showing the spider jumping.