Octopuses, crabs and lobsters are sentient and can feel pain and distress, British lawmakers have decided, in an update to a bill that could offer the creatures greater welfare protection.

The Animal Welfare Sentience Bill, which is currently making its way through Parliament, seeks to lawfully recognize the ability of certain animals to experience acute states such as suffering.

The first draft of the bill, which came out in May, was criticized by animal researchers and activists for only including vertebrates, or animals with spines.

Following the findings of a government-commissioned report by the London School of Economics, or LSE, bill has been amended to include two classes of marine invertebrates: decapod crustaceans, which include lobsters, crabs, crayfish, shrimps, and prawns; and cephalopod mollusks, which include octopuses, squids and cuttlefish.

"The science is now clear that decapods and cephalopods can feel pain and therefore it is only right they are covered by this vital piece of legislation," said the United Kingdom's Animal Welfare Minister Zac Goldsmith.

The government said that the bill will provide assurances that animal wellbeing is considered when developing new laws, and will not impact any existing legislation or industry practices such as fishing methods or cooking live lobsters.

"There will be no direct impact on the shellfish catching or restaurant industry," the Department for Environment, Food and Rural Affairs said in a statement. "Instead, it is designed to ensure animal welfare is well considered in future decision-making."

Even so, the LSE report does recommend against certain practices which are common in the processing of marine animals, including declawing, eyestalk removal, and "extreme slaughter methods such as live boiling without stunning."

The report evaluated evidence from 300 studies to reach its conclusions. The LSE team said that while they do not have spines, decapods and cephalopods have complex central nervous systems, one of the key hallmarks of sentience.

Jonathan Birch, who led the report and is principal investigator for the Foundations of Animal Sentience project at the LSE, welcomed the amendment, saying it helped "remove a major inconsistency".

"Octopuses and other cephalopods have been protected in science for years, but have not received any protection outside science until now," Birch said. "One way the UK can lead on animal welfare is by protecting these invertebrate animals that humans have often completely disregarded."

Animal sentience is recognized under European Union law, and welfare groups had been concerned that animals might lose certain legal protections when the UK left the EU. In May, the government outlined its plans to include a number of animal welfare measures in post-Brexit legislation.

These include, among other measures, a recognition of animal sentience, an end to the export of live animals for fattening and slaughter, mandatory cat microchipping, and a bill to outlaw the keeping of primates as pets.