Training spiders to jump on command

Because why wouldn't you want to do this ?

Scientists have trained a spider to jump on command in the hopes that it will inspire a new generation of robots modelled on nature.There are lots of spiders that have the ability to jump, and the regal jumping spider (Phidippus regius), which the researchers used in this particular study, is no misnomer. The regal jumping spider's technique is impeccable, and when they leap to catch their prey, they can soar as far as six times their body length. This means at roughly 15 millimetres in length, these little fellas can jump at least 60 millimetres. In comparison, humans can barely manage to jump 1.5 times our body length.

The footage revealed that Kim had several different jumping techniques. At close range (roughly two body-lengths), Kim prefers a faster, lower trajectory for speed and accuracy. But for longer leaps (roughly six body-lengths), she tends to use a more energy-efficient jump. The researchers also noticed that Kim attached a "silk safety line" to the platform before taking off, which could be a way for the spider to stay stabilized as she jumps.

While biologists know that spiders use hydraulic pressure from fluid in their legs to extend their limbs, it's still up for debate whether spiders can also use hydraulic pressure to enhance or even replace muscle power. In this particular species, however, the researchers spider's muscle power alone was sufficient for the jump. "Our results suggest that whilst Kim can move her legs hydraulically, she does not need the additional power from hydraulics to achieve her extraordinary jumping performance," says one of the team, aerodynamics researcher Bill Crowther. "Thus, the role of hydraulic movement in spiders remains an open question."

But how does one go about training a spider ? National Geographic has a few insights :
https://news.nationalgeographic.com/2018/05/spiders-jumping-engineering-mechanics-animals-spd/

“She would eat a cricket per week, so we couldn’t use a rewards system [to train her],” study author Mostafa R.A. Nabawy says. “And if we just gave her prey, then she would only jump motivated by the food. Then we would have to wait a week between jumps.” Instead, Nabawy and his team manually moved Kim from one platform to the other. They repeated this process until Kim was conditioned to make the jump without their assistance.

Which also notes :

Nabawy is convinced that she has the power to jump even farther, but he suspects that her vision doesn’t allow her to see the platform clearly past six body lengths.

Next up then : glasses for spiders.

https://www.sciencealert.com/scientists-regal-jumping-spider-on-command-robot