A common belief suggests that killing a pregnant spider causes its babies to burst out. This concern envisions a dramatic release of baby spiders if a gravid female is crushed. This notion generates fear and misunderstanding about spider biology. Exploring the biological realities clarifies what truly happens.
The Myth and the Reality
The idea that killing a pregnant spider causes its babies to burst out is not accurate. Spiders do not carry young internally in a way that leads to such an emergence upon the mother’s death. Unlike mammals, most spiders reproduce by laying eggs. These eggs are typically enclosed within a protective silk egg sac, external to the female’s body. The egg sac is often carried by the female or deposited in a safe location; therefore, crushing a spider with an egg sac might damage the sac or release the spiderlings within it, but they would not “explode” from the mother’s body.
How Spiders Reproduce
Spider reproduction primarily involves the female laying eggs, which are then encased in a silk egg sac; after mating, a female constructs a silk sac around them, providing protection and a stable environment for development. The number of eggs within a sac varies widely by species, ranging from a few dozen to several hundred. The spiderlings develop entirely within this egg sac, undergoing several molts before they are ready to emerge. Some female spiders carry their egg sacs attached to their spinnerets or held by their chelicerae, while others secure them in secluded areas like webs, burrows, or under leaves. A small number of spider species exhibit ovoviviparity or viviparity, where eggs hatch internally or live young develop inside the mother; in these rare instances, the young do not burst forth from the mother’s body if she is killed, but would simply die along with her or, if near full-term, might emerge prematurely without survival prospects.
What Happens to Spider Offspring
If a female spider carrying an external egg sac is killed, the fate of her offspring depends on the circumstances. The egg sac might be physically damaged or destroyed during the event. If the sac remains intact, the developing spiderlings inside could still be viable for a period, though they would lack the mother’s protection and care. Without the mother to guard the sac from predators, parasites, or environmental hazards, the chances of the spiderlings surviving to hatching are significantly reduced. If the spider is one of the rare species that carries live young internally, the death of the mother would typically result in the death of the developing spiderlings; any premature emergence would be due to physical disruption, and the young would not be able to survive independently.