It’s obvious when a dog or a cat feels pain. Their eyes widen, they tuck their tails, and they yelp out in pain. Their reactions to pain are like ours, but what about a crab or lobster? A crab may scuttle away from a painful scenario but is that due to pain or simply reflex? You are not the only one who has wondered if crustaceans feel pain. Researchers have studied this hypothesis for years, and their results may have you think twice the next time you plan a lobster dinner.
What Is a Crustacean?
A crustacean is an animal that has a hard exoskeleton (shell) with a segmented body and jointed legs. Most of these unique creatures live in water, but some species do live on land. Crab, lobster, and shrimp are among the most common, but there are over 80,000 species of crustaceans!
Decapods are an order of crustaceans in the class Malacostraca, the largest of the six crustacean classes. Decapod translates to “ten-footed,” so the creatures in this order have five pairs of walking legs, which equals ten feet. These include crabs, lobsters, crayfish, prawns, and shrimp. Studies on whether crustaceans feel pain were performed on the animals in this class.
The History of The Question: Do Crustaceans Feel Pain?
Whether or not animals feel pain has been argued for centuries. Before recent scientific research, these arguments were based on theories and philosophy. Rene Descartes was a French philosopher in the 17th century who believed that animals could not feel pain as they lacked consciousness or self-awareness.
Jeremy Bentham was a British philosopher who published a book called, An Introduction to the Principles of Morals and Legislation. This book discussed the issues with how humans treated animals. He quoted in the book, “The question is not, can they reason? Nor, can they talk? But, can they suffer?”
Bernard Rollin was the principal author of two federal laws in the United States that regulated animal pain relief. He documented that researchers in the 1980s were still unsure if animals felt pain. He also commented that veterinarians were trained to ignore an animal’s pain response. It wasn’t until the 20th century that scientific investigations began.
In 2012, American philosopher Gary Varner concluded that vertebrates (mammals, birds, reptiles, amphibians, and fish) experience pain. However, he also stated that cephalopods (squid, octopus, and cuttlefish) were the only crustaceans that felt pain.
What Defines Pain?
The pain response is a physical, mental, and emotional reaction. The two components to measuring pain are the physical response (reflex) and the ability of an animal to experience suffering. Suffering is an emotional response that can’t be directly measured in animals as it can in humans. It’s impossible to tell if an animal is experiencing pain by observation only.
A lobster frantically trying to pull its crushed claw from under a rock does not prove it feels pain. This reaction could be determined as a reflex. For example, you put your hand on a hot stove but pull your hand away before any pain is felt. This is a reflex response. It can’t be proven that crustaceans feel pain based on their physical response. The emotional response, “suffering,” must be determined to conclude that crustaceans feel pain.
How to Determine Pain from Reflex in Crustaceans?
Robert Elwood is a scientist and biology professor who has studied crabs and prawns for decades. When asked the question, “do the crustaceans feel pain?” Elwood decided to find out the answer. He conducted several experiments to determine a crustacean’s reflex from an actual pain response.
His first experiment was brushing acetic acid onto the antennas of prawns. The prawns responded by grooming the injured antenna for prolonged periods while ignoring the healthy antenna. When Elwood applied an anesthetic before the acid, the prawns did not groom the antenna as much.
Another experiment Elwood conducted was briefly shocking one part of a hermit crab. The crab would rub the injured area for extended periods. If a claw was removed, the crabs would rub the injury and pick at the wounded area. Elwood quoted, “these are not just reflexes. This is prolonged and complicated behavior, which clearly involves the central nervous system.”
So, Do Crustaceans Feel Pain?
Recent studies are beginning to provide evidence that crustaceans do indeed feel pain. These studies prove that crustaceans experience more than a reflex when presented with something “painful." To truly prove that a crustacean feels pain as humans do, it would require the crab or lobster to be able to communicate that. However, there is enough evidence to protect crustaceans with the “precautionary principle.” This means that even though the evidence is inconclusive, people should “err on the side of caution” regarding the welfare of crustaceans.
The Swiss government has passed a new law that requires lobsters to be made unconscious before being boiled. In New Zealand, it’s illegal to boil lobsters alive. The UK released an official report in November 2021 stating that crustaceans are capable of feeling pain. In the report, researchers recommended that crustaceans be counted as “animals” and placed under the animal welfare act.