Specimen Showcase｜Hidden Mastermind in the Jungle

In the lush forests🌴, a spider senses a subtle touch in its finely spun web – a signal of a potential meal ensnared🕸️. Excited by the prospect of a succulent catch, it hurries to investigate, just to find no prey trapped on the net. When the spider is still wondering what just happened, ZING! A 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 (Thorell, 1887), also known as White-Moustached Jumping Spider jumps from nowhere and grabs the unsettled spider, finally giving them the deadly bite🥊.

𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 lives in Southeast Asia, in countries like Sri Lanka, India, southern China, Myanmar, Malaysia, Singapore, Java, Sumatra and the Philippines. Their females are usually larger than the male, as their size ranges from 7 to 10 millimetres, while the males have sizes ranging from 5 to 7.5 millimetres. This sexual dimorphism also extends to their appearance as if both sexes present an orange-brown carapace and an abdomen that is black or brown, males will display white hairs on their surface while females show gold, black or white hairs.

𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 belongs to the Salticidae family, more commonly referred to as jumping spiders. One of the signature appearances of the jumping spiders is their 4 eyes, 2 big and 2 small located at the front of their head (cephalothorax), and 2 additional small eyes on each side of the head👁️. Unlike many other spiders that spun web to catch prey, jumping spiders have a totally different strategy. They will not sit and wait for their prey to fall for their traps, but will actively approach their prey, and that’s where their big eyes come to help. Their two large eyes allow them to receive more light, and thus see things far away👓. The smaller eyes are used for detecting movement only. As a predator, it is vital for them to determine the distance between them and their prey. To achieve such ability, animals will receive slightly different images of an object from each eye, the brain then comparing these images to determine the object's distance from the predator. Jumping spiders, however, have both eyes very close to each other, so how do they gauge the distance with their prey? They develop a method called image defocus. This method works by first focusing on an image with a known distance, then also receiving a defocused or fuzzy image. By comparing the fuzziness or how defocused the object is, they can estimate the distance of the object📷. On top of the ability to calculate distance, they can also decompose light from red to ultraviolet light.

After jumping spiders locate a prey, they need to approach it. And this approach is best described in their name: by jumping. Jumping is not a rare strategy in nature. Many animals such as the grasshoppers, kangaroos, frogs and many more jump in many situations. There’s a common trait shared by these animals, which is strong muscles in their jumping legs💪, but if we look at jumping spiders, their jumping legs, which is their last pair of legs, is quite thin and definitely lacking muscles. So how do they jump? Scientists found out that jumping spiders possess a hydraulic system built in their body, which can help their legs straighten from a curl position in a fraction of a second💉. Although 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 don’t spin webs, they can still produce silk, but for what? Right before they jump, they will attach a silk on the substrate they are originally on. This silk can help them stabilize their jump, making sure they will land on their target, and if they miss, the silk will act as a dragline, letting the spider return to a safe position.

Jumping spiders generally prey on all kinds of insects and other small arthropods, such as flies and ants🐜. But for 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢, they prey on potentially harmful and challenging organisms: other spiders, sometimes even twice their size🕷️! To do such an extraordinary feat, they don’t have any additional tools, but they will plan their hunting strategy beforehand. Some scientists even described them as possessing strategies as versatile and adaptable as lions🦁. When a 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 sees a potential prey, they would not strike even if it were in their range. Hunting a spider that is larger than their size is a lot of food for them, but it also comes with a high risk🍖. If they make any mistake, they might get injured fighting the spider, or even getting killed💀. So, they want to make sure they will strike successfully. To achieve that, they will observe the environment and find detours leading to the best position to strike. They will normally use 3-5 minutes to pursue their prey, with some use up to 10 hours to find the spot⏳. One of the best striking positions they could find is from a branch right above their potential prey, where they can hang down using a silk. When they get close enough, they will attack the prey. Sometimes their prey is not in the perfect position, but they won’t give up just yet. They will pluck the web of their target, pretending to be an insect falling on their web🕸️, luring their target to a better position. 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢 can also solve unknown problems by trial and error, helping them increase their rate of predation success the next time they encounter similar problems.

Are you amazed by 𝘗𝘰𝘳𝘵𝘪𝘢 𝘭𝘢𝘣𝘪𝘢𝘵𝘢? If you want to know more about it, and are interested in other animals, visit the Hong Kong Biodiversity Museum to observe other specimens of fascinating species. And if you found this article engaging, share it with your friends and stay tuned for our captivating biodiversity narratives released weekly!

Text: Paco

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