Underwater robot vacuums up lionfish | Science News for Students

Underwater robot vacuums up lionfish

It could remove the invasive ecosystem bullies from coral reefs and move them onto dinner plates
Jun 5, 2017 — 7:10 am EST
underwater robot

This lionfish doesn’t seem to notice the robot sneaking up behind it. A human steers the robot so its two metal bars will soon surround the fish. Then a jolt of electric current between the bars will stun the fish, allowing the robot to suck it into a holding tank.

J-P Rouja/LookBermuda

This is one in a series presenting news on technology and innovation, made possible with generous support from the Lemelson Foundation.

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The beautiful but deadly lionfish has devastated coral reefs around Bermuda and other places in the Atlantic Ocean. Native to the Middle East and Pacific Ocean, lionfish have no natural predators here. They have become invasive species, which eat many native species on the reefs. But a new robot could help efforts to control the invaders. It captures these fish. And one day diners may eat the robot’s catch.

“It’s essentially a robotic vacuum that zaps and sucks fish,” says Erika Angle. She is a biochemist and co-founder of the biotechnology company Ixcela in Bedford, Mass. She also works with a number of non-profit and outreach organizations. One of them, Robots in Service of the Environment (RSE), built the lionfish-hunting robot. At an April 2017 demonstration, her team dropped several lionfish into a large, saltwater pool. It was near the ocean in the West Atlantic island nation of Bermuda. Angle sat nearby. Using the joystick from a video-game controller, she steered the underwater robot.

operating robot
Erika Angle pilots the underwater robot using a game controller. The laptop screen shows her what the robot “sees” through its cameras.
J-P Rouja/LookBermuda

During the demo, Angle saw through the robot’s “eyes.” What that vision system picked up appeared on a laptop screen in front of her. Carefully, the scientist nudged the joystick on the controller. As she did, the robot scooted closer to a large, spiky lionfish.

A crowd of onlookers watched. Would Angle’s robot catch the fish? “Everybody was waiting with bated breath,” the scientist recalls. Finally, she pushed a button. Zap! The robot sent an electric shock through the water. This stunned the fish, which now drifted, motionless. The robot used this opportunity to slowly suck the animal into a holding chamber. The crowd cheered as Angle grinned.

Diving deep

Inspiration for the robot struck when she and her husband, Colin Angle, were vacationing in Bermuda. While scuba diving with some locals, they saw lionfish on the reef. On a boat after the dive, the group started talking about the invasive species. Several local residents had been dealing with lionfish for years. They knew that Colin Angle had co-founded the company iRobot, which makes robotic vacuum cleaners such as the Roomba. And so the group challenged the Angles to use robotics to help solve their lionfish problem.

And it’s a big problem, notes Stephanie Green. She’s a marine ecologist at Stanford University in California who is not involved in the robot project. Green compares the lionfish to a very thorny weed. A weed crops up in a garden, spreads quickly and chokes out most other plants. The lionfish is similar, but it is eating and outcompeting local fish.

Lionfish “mostly eat whatever fits in their mouth,” she says. And, she notes, over a two-year period, a reef infested with lionfish could lose 65 percent of its native prey fish.

Currently, divers help to control lionfish by nabbing them with spears or nets. Green herself has spent many hours underwater catching lionfish with nets. But people can only dive safely down to about 30 meters (100 feet). Lionfish hang out as deep as 122 meters (400 feet). Using a robot to reach these depths is “a really innovative idea,” says Green.

To bring that idea to life, the Angles recruited a team of engineers willing to volunteer their time. They tested early prototypes of the robot in a kiddie pool in a team member’s garage. To make the water as salty as the ocean, they would dump salt into the pool with a shovel and mix it up with a wooden beam. Then they would drop in the current version of the robot — and a lionfish. “Larry the lionfish was our test subject,” Erika Engle says. “He’s a trooper.”

Eat the invaders

Finally, the team was ready to show off its robot to the world. For the April event in Bermuda, they caught 13 lionfish over the course of the day out of the saltwater pool. Of course, a pool isn’t the same as a reef. But the team savored these moments. “The engineers threw off their shirts and went flying into the ocean in celebration,” Angle recalls.

The Angles and their team treated Larry, their test subject, with affection. But wild lionfish that their robot encounters won’t be so lucky. Erika Angle’s team hopes to sell robots to the fishing industry to capture lionfish for people to eat.

Most restaurants and grocery stores don’t yet offer lionfish. But activists are trying to change that. Eating the fish would be a great way to reduce its numbers. At the RSE launch event, a group of chefs competed to make the best recipe using with lionfish. Angle’s favorite was ceviche (Seh-VEE-chay). That’s raw fish marinated in citrus juice.

Green hopes that RSE’s robot will help tackle the explosion of lionfish in North American waters. But first she’d like the fish-catcher tested in a deep-ocean environment, not just a pool. She also is concerned about how much it might cost to run the robot. It could be too expensive. And she worries that wild lionfish will be tough to catch. These fish tend to approach unusual sights, such as divers or a robot. But they dart away quickly when spooked. Over time, they might learn to recognize and avoid a robot.

In a recent study, Green and her colleagues compared the behavior of lionfish living in areas with and without regular human hunting. The hunted fish hid more deeply in the reef by day. Green, however, is glad RSE is bringing attention to the lionfish problem.

And Angle’s team has big plans for its robot. They have considered letting people donate money to log into a website and control the robot remotely, almost like playing a video game. Or they might take human pilots out of the picture entirely. A drone robot that could recognize lionfish might be able to patrol the depths for the beautiful, spiky invaders on its own, then bring them into port.

Invasive lionfish are wreaking havoc on reefs. A new robot could help remove them — and get the fish onto our plates.
Robots in Service of the Environment

Note: Angle is the founder and executive director of Science from Scientists, a program that brings hands-on research projects run by real scientists into schools. Her group’s mission is to improve student interest and aptitude in STEM. It sends scientists into classrooms every other week during the school day, so far in 46 schools. Angle also was a 1999 finalist of Science Talent Search, a program created by and still run by Society for Science & the Public (which also publishes Science News for Students).

Power Words

(more about Power Words)

Atlantic     One of the world’s five oceans, it is second in size only to the Pacific. It separates Europe and Africa to the east from North and South America to the west.

behavior     The way something, often a person or other organism, acts towards others, or conducts itself.

citrus     A genus of flowering trees that tend to produce fruits with a juicy edible flesh. There are several main categories: the oranges, mandarins, pummelos, grapefruits, lemons, citrons and limes.

colleague     Someone who works with another; a co-worker or team member.

coral     Marine animals that often produce a hard and stony exoskeleton and tend to live on reefs (the exoskeletons of dead ancestor corals.

ecology     A branch of biology that deals with the relations of organisms to one another and to their physical surroundings. A scientist who works in this field is called an ecologist.

engineer     A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

invasive species     (also known as aliens) A species that is found living, and often thriving, in an ecosystem other than the one in which it evolved. Some invasive species were deliberately introduced to an environment, such as a prized flower, tree or shrub. Some entered an environment unintentionally, such as a fungus whose spores traveled between continents on the winds. Still others may have escaped from a controlled environment, such as an aquarium or laboratory, and begun growing in the wild. What all of these so-called invasives have in common is that their populations are becoming established in a new environment, often in the absence of natural factors that would control their spread. Invasive species can be plants, animals or disease-causing pathogens. Many have the potential to cause harm to wildlife, people or to a region’s economy.

marine     Having to do with the ocean world or environment.

native     Associated with a particular location; native plants and animals have been found in a particular location since recorded history began. These species also tend to have developed within a region, occurring there naturally (not because they were planted or moved there by people). Most are particularly well adapted to their environment.

Pacific     The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east.

predator     (adjective: predatory) A creature that preys on other animals for most or all of its food.

prey     (n.) Animal species eaten by others. (v.) To attack and eat another species.

prototype     A first or early model of some device, system or product that still needs to be perfected.

reef     A ridge of rock, coral or sand. It rises up from the seafloor and may come to just above or just under the water’s surface.

robot     A machine that can sense its environment, process information and respond with specific actions. Some robots can act without any human input, while others are guided by a human.

salt     A compound made by combining an acid with a base (in a reaction that also creates water). The ocean contains many different salts — collectively called “sea salt.” Common table salt is a made of sodium and chlorine.

scuba diving     A form of underwater diving in which the person carries special equipment in order to breathe, including a tank of air and a breathing mask. The word scuba is short for self-contained underwater breathing apparatus .

species     A group of similar organisms capable of producing offspring that can survive and reproduce.

vacuum     Space with little or no matter in it. Laboratories or manufacturing plants may use vacuum equipment to pump out air, creating an area known as a vacuum chamber.

weed     (in botany) A plant growing wild in, around — and sometimes smothering over — valued plants, such as crops or landscape species (including lawn grasses, flowers and shrubs). Often a plant becomes such a botanical bully when it enters a new environment with no natural predators or controlling conditions, such as hard frosts. (in biology, generally) Any organism may be referred to as a “weed” if it enters an environment and begins to overwhelm the local ecosystem.


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Journal:​ ​​I.M. Côté et al. What Doesn’t Kill You Makes You Wary? Effect of Repeated Culling on the Behaviour of an Invasive Predator. PLOS One. Vol. 9, Issue 4, published online April 4, 2014. doi: 10.1371/journal.pone.0094248.

Further Reading

National Oceanic and Atmospheric Administration. “The lionfish invasion!” A report by the U.S. agency’s Ocean Service Education. May 9, 2011.

National Oceanic and Atmospheric Administration. Lionfish biology fact sheet.

Reef Environmental Education Foundation. Tips for collecting, handling and eating lionfish.

Reef Environmental Education Foundation. Lionfish quickfacts. Oct. 25, 2011.