Reasons to love spiders #2: Those which don’t build webs are still brilliantly creative hunters
Although spider-webs are practically synonymous with the word ‘spider’, here’s something that might surprise you - only about half the world’s spider species spin webs to catch their prey! The world of spiders is very, very diverse (they rank seventh in total species diversity among all the living organisms out there) and many of them have evolved to catch prey by different, but equally impressive means.
The trapdoor spider is a fascinating example of this. Belonging to the Ctenizidae family of arachnids, this little mygalomorph constructs a burrow in the ground, and covers it with a hinged trapdoor made of leaves, soil, and silk. The trapdoor swings outwards, and is very difficult to spot on the ground when shut. Once the spider starts feeling peckish, it hides inside the burrow while holding the trapdoor closed, waiting for an unsuspecting insect to crawl by and disturb one of the trip lines connected to the door. When this happens, the spider is quickly alerted that a tasty morsel is within reach, and bam! - it instantly leaps out and captures its prey, a mere fraction of a second from when the insect came into contact with the trip line.
No time for webs OR silken trapdoor snares? Meet the vast and ridiculously adorable family of jumping spiders (Salticidae). Armed with amazing visual acuity (they have four pairs of eyes, but they’re still cute, I promise!) and the ability to jump upto 50 times their own length, jumping spiders make for formidable hunters and prefer to stalk their prey on foot and ambush it, rather than building traps. This is how they do it: once potential prey has been sighted, a jumping spider will stalk the meal-to-be for a while in order to determine whether it’s worth the effort or not (these spiders are often tiny in size compared to their prey, so there’s always a risk involved!). If yes, the spider will first release a dragline for security, and proceed to pounce on its prey with deadly accuracy, immobilising it on the spot with a quick shot of venom in order to prevent it from escaping or putting up a struggle. However, should the little spider fail in making the jump, or if the prey manages to shake if off, it will climb right back up the security line, and either make another attempt, or wander off in search of other prey. Clever things!
Of course, these are only two of many, many fascinating examples, with more to be covered in the future! Here is part one of the installment.