Hackaday Prize 2022: Otter Force One Protects Kelp Forests By Sucking Up Sea Urchins

A device with pipes and pumps sitting next to a body of water

When thinking about forests being endangered by human activity, most people would immediately think of the rainforest. Below the ocean surface, there’s another type of forest is in danger: the kelp forests off the coast of northern California. Warming sea water has triggered an explosion in the population of purple sea urchins (Strongylocentrotus purpuratus) which devour kelp at an alarming rate. It’s estimated that 90% of kelp forests have been lost to the urchins along a 350 km stretch of coastline.

The fix is as simple as getting rid of the urchins, but collecting the millions of spiny creatures manually isn’t realistic. Luckily, [RobotGrrl] designed just the tool for this task: Otter Force One, an autonomous underwater robot that can gather the aquatic interlopers and put them in a bag for removal. The device is still under development, but progress so far has been promising. The basic idea is to identify an urchin using machine vision, then dislodge it with a water jet, and finally to use a suction pump to pull it inside the machine and store it in a bag.

A prototype made from 3D printed components is currently being used to test the idea. Its motors are driven by an ESP32 with a motor controller, with the system powered by a set of beefy lithium batteries. Tests with plastic urchin models confirm that the suction mechanism works, though the water jet and machine vision systems still need to be tested. But even without these in place the Otter Force One can still be used by human divers to improve their urchin-gathering efficiency.

We’ll definitely keep an eye on this project, and hopefully see it evolve into a fully-automated urchin hunter. Underwater pest-control robots are not completely new: we already saw a laser-powered delouser for use on salmon farms. There are also robotic starfish and octopuses.

10 thoughts on “Hackaday Prize 2022: Otter Force One Protects Kelp Forests By Sucking Up Sea Urchins

  1. I like the idea but I think it would be more effective to merely kill the urchins and move on. If you can hit them with a strong enough wave of water then they will die. This would be best accomplished with a small explosive charge. Gun powder would be a cheap option but a valve controlling compressed nitrogen would be less of a pollutant and not require a loading mechanism.

    1. Here’s a thought, every marine biologist i have ever met uses electrodes dipped into the water to send shocks to the water that will stun the nearby fish, and thus allow the biologists to count them. maybe, this idea could be used to “stun” the urchins, and make it easier for the poor little robot to suck them up off the seafloor while the urchins are temporarily disoriented??

  2. If I remember correctly, when snorkeling with groups of divers to remove urchins back in the ’70s we would hammer them with a pipe or a hammer and kill them. Unfortunately, within a few years scientist reported in skin diver magazine that in the active smashing their exoskeleton sperm and egg were released from their internal sex organs and we created many more urchins over the next couple of years then we had to begin with. At that point, or snorkeling groups begin to simply remove them from the ocean bottom, put them on the beach and let them die. Somebody smarter than the rest of us decided that urchin tests (skeletons) made great fertilizer when mixed with topsoil and formed an urchin diver company and industry that made millions. They also soon realized that Asian cultures enjoyed eating urchins as another money stream… And the rest is history.
    I sure hope this machine works!

  3. Mmmm. Uni. Fantastic.

    Don’t kill them, catch them and sell them to sushi restaurants.
    Scale this up and monetize.

    Also Hamchi Kama.

    Everybody sing:
    Fish heads fish heads, roly-poly fish heads
    Fish heads fish heads, eat them up yum!

    Now I want sashimi and sake.

  4. There is a much more efficient way to do this… Urchin roe is a delicacy in most of the world. I used to dive for this in Turkey. Put the roe on a fresh piece of sourdough with a slab of butter… Pure heaven…

    As soon as people get the taste, give it a few years and the urchin will be on the endangered list. Like sharks etc…

    Just kidding. This is a great idea…

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.