Jumping spiders are known for their keen vision and agile movements. This article describes the distinctive features of baby jumping spiders (spiderlings), how their appearance transforms as they mature, and methods to distinguish them from other small spiders.
Identifying Features of Spiderlings
Baby jumping spiders are incredibly tiny, often no larger than a pinhead. Many newly hatched spiderlings are translucent or pale, with some having transparent legs that reveal internal structures. After their initial molt, some species may turn entirely black.
A defining characteristic of jumping spiders, even as spiderlings, is their unique eye arrangement. They have eight eyes, with two very large, prominent, forward-facing anterior median eyes. These large eyes provide sharp, detailed vision and depth perception, allowing them to track their surroundings. The remaining six smaller eyes, positioned around the sides, offer a wide field of view for detecting motion. Spiderlings also have a fuzzy or hairy appearance on their cephalothorax. Their overall body shape is compact and rounded, resembling miniature versions of adult jumping spiders.
Appearance Changes with Age
As baby jumping spiders grow, they undergo molting, shedding their external skeleton. This shedding allows them to increase in size, and each molt can bring about changes in their coloration and pattern development. Jumping spiders typically molt between five and ten times throughout their lives. The first molt often occurs while they are still within the egg sac.
While their fundamental body structure remains consistent, specific markings and vibrant colors become more pronounced with maturity. For instance, some species might have faint patterns or orange spots as spiderlings that intensify or change to white as they age. Some regal jumping spiders can even change their entire color palette during a molt, shifting from dark hues to lighter cream or black. Distinct markings often become visible after the third molt (third instar).
Differentiating from Other Small Spiders
Distinguishing baby jumping spiders from other small spiders or insects relies on a few key features. The most definitive characteristic is their eye arrangement; the two disproportionately large, forward-facing eyes are unique to jumping spiders. This contrasts with the varied eye patterns of other small spiders, such as wolf spiders or nursery web spiders, which have different primary eye placements and sizes.
Jumping spiderlings also have a stocky, compact body, unlike the more elongated forms of other spiderlings. Their movement patterns offer another clue. Jumping spiders are active hunters that stalk their prey with distinctive jerky, pouncing motions, relying on their keen vision rather than webs to capture food. This behavior is facilitated by a hydraulic system in their legs, enabling powerful jumps. Many other small spiders, however, rely on webs for hunting or display different locomotion.