Spiders that existed about 300 million years ago were presumed to use silk to safeguard their retreats and to build egg casings. Over the next 100 million years, spiders evolved. Their silk-producing organs, called spinnerets, were placed at the end of their underbody, contrary to the ones with spinnerets in the middle of the underbody. Their silk usage evolved too, and they employed methods like single silk draglines, sheet and maze webs to capture prey.
Prey capture behaviours in spiders vary from passive entrapments in the web to ambushing prey on foot. However, there are some techniques in between these two. A special one among them is lunging forward and trapping the prey with a silky net. And that is the unique hunting style the net-casting spider employs.
Net-casting spiders are also called ogre-faced spiders, thanks to their massive eyes. These spiders are generally drab-coloured with an elongated abdomen and legs.
During the daytime, they choose to stay in the shady and dense undergrowth, sticking their face in between their forelegs, and protecting their eyes from the harsh light. This keeps them well hidden from predators and us nature enthusiasts!
As the night falls, the spider slowly moves out of its hideout towards its hunting ground. It could either choose to hunt among the vegetation, targeting leaf-dwelling prey or can very well choose a point above the ground to target ground-dwelling prey.
After it reaches its hunting ground, it carefully starts building a triangular-shaped structure with its silk, which acts as the resting point for the spider itself. Once the structure is ready, it starts weaving the net.
The net is usually built by carefully strumming the silk using its hind leg and delicately placing it on the outline that is already built. The strumming makes the silk very stretchy, which helps in casting the silk at the prey. Once the net is ready, the spider turns and gently holds the net, carefully plucking it, stretching it and sometimes doing a mock casting too.
Once the spider senses the prey, it casts the net and packs the prey up.
The construction of a new net depends on how big the meal was. This repeats through the night and as the dawn starts creeping in, the spider winds up the net into a ball and feeds on the silk, keeping the outline silk structure intact.
Net-casting spiders were thought to be visual predators, ensnaring prey by lunging downward with the net held between their front four legs. Their massive pair of hypersensitive, night-vision eyes aid them in this forward strike.
Recently, scientists have discovered that they use auditory cues to detect flying prey. Studies show they can also intercept flying insects with a backward strike, a rapid, overhead back-twist that relies on sound detection and that they can detect auditory stimuli from at least 2 m from the sound source.
Male net-casting spiders are slender and smaller when compared to females.
Courtship and mating occurs on the web as well. The male finds a female and approaches her with carefully calculated steps only to stop almost a feet away. If the female approves of the male and his intent she approaches him.
When the male and female are within grasping distance, the female displays her abdomen to the male and allows him to proceed. The male is ready with extended pedipalps.
The male with his extended pedipalps hurriedly rushes towards the female and starts mating.
Mating ends within two minutes and the male quickly rushes away from the female.
By observing net-casting spiders up close, I found several life lessons. They follow a specific routine like clockwork and always repeat actions at the same time. In fact, all of them start building their nets at a specific time every day! Once the net is built, they patiently wait for prey and do not miss any opportunities to lunge forward at the prey, whether they succeed or not.
Nature has many learnings to offer, go grab some!