The male spider carefully approaches the female and begins a choreographed courtship dance unique to his species. She watches, waits and decides he's a suitable mate. Wary of her bigger size, he transfers his sperm to her and, if he's lucky, speeds away with his life. She fertilizes her eggs with his sperm. Up to this point, spiders are all the same. What happens once the eggs are laid varies drastically among species, though, from a little nurturing TLC in the early days to total abandonment.
A mother spider does one of several things once her eggs are laid. Some spiders, such as some wolf spiders, carry their egg sacs behind them, dragging them with a short strand of silk. Wolf spiders also mend defects in the egg sacs, and some sun their egg sacs in sunlight. Many web-building spiders suspend their egg sacs somewhere in the web and dutifully stand guard. Other spiders may lay out sheets of silk to protect their fragile egg cases.
Maternal care isn't completely void in spiders, although it can be somewhat of a rarity. Some mother spiders, particularly wolf spiders, are much more involved in their offspring's lives and much more protective over their young. Just before hatching, a mother wolf spider perforates the egg sac to help the immature spiders out. Mother wolf spiders carry their young on their backs; the young entangle their legs together to keep hold. Mother wolf spiders even help their babies drink water, leaving a few legs in the water source and allowing the immature spiderlings to climb down.
Some spiders, such as the social Dieaea ergandros, conduct a behavior known as matriphagy, or the act of the young eating their mother. matriphagy is uncommon in the animal world, but somewhat common among different species of spiders. Dieaea ergandros spiderlings live in the nest, feeding on large meals the mother brings back. The mother feasts on the leftovers of the large meals, storing nutrients in unfertilized eggs, which seep into her bloodstream when autumn approaches and food sources are depleted. The hungry spiderlings, like small vampires, begin to suck the nutrient-rich blood from their mother's legs. Once she is too weak to move, they then inject venom into her and attack her as they would prey. Amaurobius ferox, a European spider, has a different matriphagy ritual. After the spiderlings' first molt, the mother drums with her legs to create somewhat of a dinner bell. She then presses against her brood of tiny spiders and they then swarm her and attack her, feeding voraciously on her body.
No Maternal Care
Many species' spiderlings hatch and simply fend for themselves. They either walk to new locations or travel by ballooning, a process whereby the tiny critters let loose a strand of silk that carry them miles away in the wind.
- Life Sciences at Brandeis: What Is a Spider?
- University of Rhode Island Landscape Horticulture Program: Spiders
- Arkansas Academy of Science Proceedings; Maternal Care as Exhibited by Wolf Spiders; Ruth Robinson Eason
- The Royal Society; Offspring Recognition by Mother Crab Spiders With Extreme Maternal Care; Theodore A. Evans
- Monte Vista School District: Having Mom for Dinner
- Ablestock.com/AbleStock.com/Getty Images