Protecting The Lobster In The Lab

We know them as lobsters, crabs, and crayfish. Science knows them as decapod crustaceans. Members of this order are widely used in research. They are easy to collect, and their biology and sensitivity to pollutants make them valuable to scientists. They also satisfy requirements to reduce the use of vertebrates in scientific studies. Decapods are considered non-sentient and thus their treatment falls outside even strict European animal welfare laws. However, research is calling this assumption into question. It appears likely that they experience pain and have the capacity to suffer.

The authors in this study reviewed the use of decapod crustaceans in research and discussed the latest evidence that may point to their sentience. The neural complexity of invertebrates varies widely. Some have only diffusely organized nervous systems, while others have complex neurobiology with large numbers of neurons. Crustaceans have gained recent favor with researchers because they have advanced circulatory hormones, immune systems, individual traits, tolerance to handling, high fertility, and are of suitable size with a short generation time. They are also quite adaptable to varied environmental and nutritional conditions.

Pain perception in decapods was initially thought to arise purely from nociception. Responses to aversive stimuli were only reflexive, so nerve signals that caused withdrawal from such stimuli did not reach the central nervous system. Thus, according to some, there was no noxious experience. However, if responses are non-reflexive, they may be mediated by pain. They may also cause a learned response that will help the animal in the future. 

To assess whether decapods in fact experience pain, the researchers identified eight behavioral criteria for animal pain. They then looked for experiments on decapods for each of these items. The criteria are as follows.

1. Protective motor reactions such as limping, rubbing, and prolonged licking
2. Tradeoffs between avoidance responses and other motivations such as securing better shelter or a safer environment
3. Long-term motivational changes where an animal alters its behavior past the minimum time needed to avoid a noxious situation
4. Paying a cost to avoid a noxious stimulus, which would suggest some sort of evaluative process
5. Avoidance learning in response to a painful or unpleasant stimulus
6. Anxious behaviors
7. Effects of anesthetics and local analgesics that appear to block pain or soothe a body part that is injured
8. Physiological responses to pain such as changes to heart rate, respiration or hormone levels that equate with a stress response

The analysis included experiments on a variety of crustaceans such as crayfish, hermit crabs, shore crabs and glass prawns. Results suggest that decapods can in fact feel pain and exhibit sentience and that their experience is more than one of nociception. And if they do in fact suffer, we need to revise animal welfare laws to take decapods into account — and laboratory researchers must give them due ethical consideration and take steps to minimize their pain and reduce their suffering. As animals used for food, humane handling and slaughter is also essential. 

This is the current state of research, and until we have more definitive answers, we should apply the precautionary principle. Advocates can work with research funders and governments to advance our understanding of these animals. Armed with this information, we can advocate for corrective legislation and for due moral consideration for the lives of these creatures.