Spiderlings, often referred to as baby spiders, represent the initial developmental stage of spiders after they hatch from their eggs. Despite their minuscule size, these newly emerged arachnids appear as miniature versions of their adult counterparts.
What Spiderlings Look Like
Spiderlings are remarkably small, with many species no larger than a pinhead or a grain of sand upon hatching. Some larger species, like certain tarantulas, may have spiderlings measuring around 0.25 to 0.75 inches in leg span. Their coloration often begins pale, translucent, or white, gradually darkening as they age and undergo molts. The specific colors can vary widely depending on the spider species.
Like adult spiders, spiderlings possess a body divided into two main segments: the cephalothorax (a fused head and thorax) and the abdomen. These two segments are connected by a slender waist known as the pedicel. Spiders, even in their earliest stages, have eight legs, all attached to the cephalothorax. While they have simple eyes, typically six or eight depending on the species, these can be challenging to discern due to their tiny size. Initially, their body proportions might appear slightly different from adults, sometimes with a relatively larger abdomen compared to the cephalothorax.
Early Life and Development
Spiderlings begin their lives hatching from silk-encased egg sacs, which can contain anywhere from a few to several hundred eggs. Some female spiders, such as wolf spiders, guard their egg sacs or carry them until the spiderlings emerge. Immediately after hatching, spiderlings are vulnerable. Many species remain within the egg sac for their first molt before venturing out.
Growth in spiderlings occurs through molting, or ecdysis, where they shed their rigid outer exoskeleton. After each molt, their appearance can change as they become larger and their colors more defined. Their newly formed fangs are soft and require time to harden before they can effectively capture prey. Spiderlings molt frequently during their rapid growth phase, often monthly for very young individuals. Following one or more molts, spiderlings disperse from their hatching site, often by walking short distances or by ballooning, where they release silk threads to catch air currents, carrying them to new locations.
Telling Spiderlings Apart
Distinguishing spiderlings from adult spiders relies on their size; spiderlings are minuscule compared to their mature counterparts. Newly emerged spiderlings often appear in groups, clustered together near their egg sac, whereas adult spiders are more solitary.
To differentiate spiderlings from other small insects or arachnids, several anatomical features are helpful. The most definitive characteristic is the leg count: spiderlings, like all spiders, possess eight legs, while insects have six legs. Spiders, including spiderlings, have two primary body parts—the cephalothorax and the abdomen—unlike insects, which have three distinct segments: a head, thorax, and abdomen. Even at their small size, spiderlings exhibit movements and behaviors associated with spiders, which can aid in their identification.