Zebra Jumping Spiders
Due to lockdown, I've been spending a lot of time in my back garden. As I said in my last post, most of my attentions has been directed to garden birds. However, my intrigue has recently been captured entirely by one tiny arachnid.
One morning I was waltzing around with my battered Nikon D3100 searching for insects and small plants, when I noticed movement on the wooden fence, bathed in sun.
It was a zebra jumping spider, and I was delighted. I have a big respect for spiders, but admittedly I do try to stay out of their way. I don’t mind the false windows or tube web spiders, because I always know where they are. But I have an issue with the way that house spiders seemingly apparate and wander aimlessly, like an eighteen year old on a gap year.
However, the zebra spider is different. I have been enthralled by these incredible ambush predators since I was about ten years old when I discovered one on the old stoney wall outside my nan's house. I spent the entire afternoon sat on the pavement, watching the spider hunting.
Ten years later and the zebra spider remains my favourite non-avian creature. I don't know whether it's the skill and agility of the spider that fascinates me, the striking colours and patterns unique to each spider, or if it's the fact that they're just pretty damn cute when you get up close. I know, I know, we shouldn’t favour wild creatures because of how sweet they look, but come on.
(not my photo)
It turns out that my garden houses quite a few zebra spiders who live between the wooden panels of the garden fence. It takes a lot of self restraint not to give them a little poke every once in a while to entertain my childish excitement when they leap, but using my adult-brain I am even more enthralled by the mechanics of the spiders's jump.
The mechanics of the jumping spiders
The zebra spider (Salticus scenicus) is one of 5000 species of jumping spider, making the family the largest of any group of spiders in the world. These tiny spiders are just 5-8mm in length, yet can jump up to 10cm. Their legs are flexed by muscles, but they lack extensor muscles. To overcome this, extension at several points of the leg is achieved by high blood pressure created by the contraction of muscles in the cephalothorax. Jumping spiders might be small, but they are incredibly mighty — excuse the cliché.
As well as their physical endurance and adaptions, jumping spiders have very powerful brains. They have three-dimensional vision more associated with larger, vertebrate creatures. In the 1980s-90s, Robert R. Jackson of the University of Canterbury demonstrated how jumping spiders can hunt out and methodically plan winding routes in order to sneak up on prey. Being able to visualise and plan ahead for its prey's location is an amazing feat for an animal who's brain is just the size of a sesame seed.
So when you're in your garden during this lockdown period, or indeed any time between April and October, look out for these astounding little spiders. One of the biggest lessons we can learn from observing nature is that there is so much more to each creature than meets the eye - the zebra spider is testament to the phrase "don't judge a book by its cover."
And bonus points to you if you can get a good snap of these speedy vaulters, because I've yet to get any!