Certain spider species exhibit a unique maternal behavior: carrying their developing young directly on their bodies. This strategy, uncommon among most invertebrates, highlights significant parental investment. Unlike many spiders that simply lay eggs, these mothers actively transport their offspring, providing protection and mobility during a vulnerable developmental stage.
Wolf Spiders: The Primary Carriers
Wolf spiders (family Lycosidae) are primary examples of spiders exhibiting this maternal care. These ground-dwelling spiders, found in various habitats, are robust, often hairy, and typically brown, gray, or black. They are active hunters, relying on keen eyesight and speed rather than webs to capture prey.
Maternal care for a wolf spider begins with the egg sac. After laying her eggs, the female encases them in a spherical silk sac, which she attaches to her spinnerets. She carries this sac continuously, even while hunting, guarding it fiercely and ensuring it receives warmth from the sun. This attachment allows her to move freely while keeping her offspring secure.
When the spiderlings are ready to hatch, the mother wolf spider tears open the egg sac. The newly emerged spiderlings, often numbering over a hundred, instinctively climb onto their mother’s back, clinging to specialized knobbed hairs on her abdomen. They remain on her back for several days to a few weeks, relying on her for transport and safety until they are large enough to disperse.
Why Spiders Carry Their Young
The behavior of carrying young offers significant survival advantages for both the spiderlings and the species as a whole. For the vulnerable spiderlings, riding on their mother’s back provides immediate protection from many predators and harsh environmental conditions, such as sudden temperature changes or flooding. The mother’s presence also shields them from desiccation, ensuring they remain in a more favorable microclimate.
This form of parental care also ensures the young have access to a mobile and relatively safe environment during their early development. As the mother continues to hunt, the spiderlings are transported to new areas, potentially increasing their chances of encountering food sources once they disperse. This extensive maternal investment, although demanding for the female, significantly increases the likelihood of her offspring surviving to maturity, contributing to the species’ overall success.