Arrow-shaped Micrathena

Meet the Arrow-shaped Micrathena (Micrathena sagittata), a small orb-weaving spider with one of the most unusual appearances. Despite the intimidating spikes, this fascinating little spider is not harmful to humans.

Female Arrow-shaped Micrathenas are easy to recognize thanks to six sharp, thorn-like projections called tubercles on their abdomen. The largest pair extends outward from the rear, giving the spider its distinctive arrow-like shape. These projections have earned the spider the nickname “Pikachu spider,” because the rear spikes can resemble Pikachu’s ears! But those spikes aren’t meant to frighten people. Instead, they serve as a defense against predators. The spider’s hard, spiny body can make it difficult for a predator to swallow.

Another interesting feature of the Arrow-shaped Micrathena is how dramatically different males and females appear. Females can grow to around 9 millimeters long and have striking yellow-and-red coloring along with their prominent abdominal spines. Males are much smaller, measuring only about 4–5 millimeters, and are generally brownish-black, smooth, and completely lacking the impressive spikes. Their inconspicuous appearance makes them easier to overlook.

Like other orb-weavers, Arrow-shaped Micrathenas create beautiful, circular webs to capture their prey. Their webs have an open center, or hub, with a small opening that allows the spider to move quickly through the middle. Their hunting strategy is interesting, too. Rather than wrapping their prey in silk first, Micrathenas typically bite and paralyze their prey before wrapping it in silk.

These tiny spiders also have an impressive escape strategy. If you happen to disturb one while it is sitting in the center of its web, it may suddenly drop straight down into the leaf litter, seemingly disappearing into thin air! The spider uses a silk dragline to make its getaway and can later climb back up the silk line once the danger has passed, returning to its web.

The Arrow-shaped Micrathena is just one of the many fascinating creatures that call Old Cahawba home. From rare wildflowers and historic trees to insects and spiders, the landscape is filled with reminders that there is always something new to discover. So, the next time you spot one of these bizarre little spiders while exploring Old Cahawba, don’t be afraid. Take a closer look and appreciate one of nature’s wonderfully strange little creations