Six ways a jumping spider is cooler than your cat

There’s a hairy beast out on the prowl. It spots its prey from a distance, stalks along the forest floor, and pounces with a mighty flying leap. It then proceeds to suck its prey dry.

This animal is, of course, a tiny jumping spider.

You may not be used to thinking of spiders as strategic hunters, but jumping spiders have cat-like talents, bundled in package smaller than a dime. Take a look at how these spiders make your house cat look like an amateur hunter.

  1. All-Seeing Eyes

Although most spiders have poor eyesight, jumping spiders are adapted for keen eyesight. They  have two specialized, forward-facing “principal eyes” designed like acute binoculars, each with two lenses and a narrow field of vision. The lenses in these binoculars are actively moved by muscles in the head – a feature uncommon in invertebrates – which allows the spiders to scan the environment or track a target without moving their body. Their eyes can see a wide range of colors, including ranges of light outside of the range of human vision1. These spiders hunt visually, by spotting and stalking distant prey, but actually have better visual resolution than cats2.

Diagram of a principal eye. Like a telescope, it has two lenses

Diagram of a principal eye. Like a telescope, it has two lenses3.

In some translucent species, you can even watch the principal eyes move!

While the principal eyes allow the jumping spider to discriminate details in distant objects, their six secondary eyes give them the ability to sense movement in any direction, making them impossible to sneak up on. Few small animals are visual, but jumping spiders are exceptional: not only can they see in high resolution, they can also detect motion in any direction! (Cats, however, do not have eyes in the back of their heads.)

The 360° field of view of a jumping spider.

The 360° field of view of a jumping spider4.

  1. Compact Brains

One might assume that spiders are simple and unintelligent, but in fact that is not always the case. Even though jumping spiders are small, with poppy seed-sized brains, they are surprisingly capable of visual processing, hunting and stalking, and mating displays. That’s everything a lion can do except roar, all at a small size and with low power.
However, much of what happens in a jumping spider’s brain is a mystery – only last year did researchers discover how to probe the brain of a live jumping spider. A spider’s body is pressurized, so whenever a cut was made in one to insert a probe, the spider would bleed out and die. Researchers were at last able to probe a live spider brain by making a tiny hole that would naturally seal around a hair-sized electrode, and record its neural signals5. With these probes in place, they can investigate how their brains work, and how visual information from eight eyes is integrated and processed, which may help inspire better miniature computers.

  1. Extreme Acrobatics

Many spiders build webs, then sit and wait for prey to become entangled. Jumping spiders do not build webs, but rather nomadically hunt for prey, and attack with an accurate jumping strike. As I mentioned earlier, their bodies are pressurized, so they can move their limbs by altering the pressure of their internal body fluid. This enables them to jump distances up to 25 times their body lengths with neither large leg muscles nor a running start6. For a house cat, that would be the equivalent of a standing jump of 12.5 yards (11.5 m)7!

A jumping spider leaps towards its prey – a tethered fly

A jumping spider leaps towards its prey – a tethered fly8.

  1. Sneaky Hunters

Jumping spiders are the lions of the invertebrate world. Like cats, they roam, detect prey through vibrations and vision, then stalk and pounce. While stalking, they can take indirect routes to get a better angle of attack on their prey, which may involve losing line of sight to the prey3. They may climb to a higher vantage point, or run behind a barrier, staying hidden from view, until an opportune moment to strike. In contrast, most small animals forget that an object exists after losing line of sight! Cats can stalk similarly, but with much larger brains, and without the advantage of walking on walls and ceilings.

  1. Performance Artists

When looking for animals with dazzling mating displays, one might think first of tropical birds. Surprisingly, jumping spiders also have some beautiful and dynamic mating rituals. In species known as “peacock spiders,” the males are distinctly sparkling and neon colored, and engage in elaborate courtship9. On the internet, their mating dances can be found recorded and set to music. Jumping spiders also produce mating calls by drumming on the ground. Each species has its own beat and rhythm, and the females prefer males with stronger, more precise, beats. As much as I love cats, they are not known for their performance art.

A male Peacock Spider performs its mating ritual

A male Peacock Spider performs its mating ritual10.

  1. Great Around the House

Jumping spiders are common on all continents except Antarctica, and can be found in habitats from fallen leaves to forest canopies to mountain tops. They are small enough that you may not have even noticed them, but you can probably find them around your house. A number of species are local to the U.S., such as the bold jumper (pictured below), which has iridescent mouthparts and black-and-white stripes. They are harmless – most are too small to break human skin, and in those that can, their bite would be no worse than a mosquito bite. Jumping spiders hunt other critters in the house, such as venomous spiders, flies, and other pests. But unlike most spiders, they don’t make webs, and unlike your cat, they will never shed or leave dead prey at your doorstep.

The bold jumping spider, common throughout North America

The bold jumping spider, common throughout North America11.

Jumping spiders behave like cats, but have telescopic vision, miniaturized brains, ridiculous acrobatics, and dynamic performing arts. They also have amusing behaviors like chasing laser pointers. It’s a shame that jumping spiders are too small to make good pets, since they can be kind of cute, in a spidery sort of way.

 

Notes and References

  1. Livescience.com: Why spiders have eight eyes

  2. Newscientist.com: Smarter than the average bug/

  3. Researchgate.net: Eight-legged cats and how they see- A review of recent research on jumping spiders (Araneae Salticidae)

  4. Wikipedia.org: Jumping spider

  5. Cornell.edu: Researchers record sight neurons in a jumping spider brain

  6. NIH.gov: More than a safety line: jump-stabilizing silk of salticids

  7. 25 body lengths for a 10 mm spider = 25 cm = 9.8 in. 25 body lengths for a 46 cm cat = 11.5 m = 12.5 yards. Average house cat size from https://en.wikipedia.org/wiki/Cat#Anatomy

  8. PNAS: Inner Workings: Inside the mind of a jumping spider

  9. National Geographic: New “Blue Face” Peacock Spider Is Fancy Dancer

  10. Wikipedia.org: Maratus volans

  11. Wikipedia.org: Phidippus audax

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