What's the kindest way to kill a lobster?

"Lobster is one of those rare foods that you cook from a live state," the recipe says.

"Quickly plunge lobsters head-first into the boiling water... Boil for 15 minutes," the recipe then instructs.

It's the tried-and-trusted method for many of us with any experience of cooking lobster - and there are dozens of similar recipes online.

But on Wednesday Switzerland banned the practice and ordered that lobsters be stunned before being despatched to our plates to avoid unnecessary suffering in the kitchen.

It comes amid growing scientific evidence that lobsters - and other invertebrates, such as crayfish and crabs - are able to feel pain.

So what's wrong with the traditional method? And what are the alternatives?

Animal welfare scientists define pain as "an aversive sensation and feeling associated with actual or potential tissue damage", explains Jonathan Birch, assistant professor in philosophy at the London School of Economics.

Defined like this, experiments suggest crustaceans do feel pain, Dr Birch explains in his article "Crabs and lobsters deserve protection from being cooked alive".

In a series of experiments at Queen's University in Belfast, crabs gave up a valuable dark hiding place after repeatedly receiving an electric shock there.

"They were willing to give up their hideaway in order to avoid the source of their probable pain," said Prof Robert Elwood, who led the team carrying out the experiments. He told the BBC that numerous experiments showed "rapid avoidance learning, and [crustaceans] giving up highly valuable resources to avoid certain noxious stimuli" - consistent with the idea of pain.

Crustaceans don't necessarily exhibit signs of pain that are easily recognisable to humans, say welfare activists. Stress-induced behaviours include thrashing, trying to escape and autotomy - where body parts are shed by the animal in response to damage or capture.

This might explain why they are excluded from many countries' legislation on animal welfare - though decapod crustaceans are protected in countries like Norway, New Zealand and Switzerland, and there are campaigns for change elsewhere.

Humanely, say activists - whereby they are killed immediately or put into a state of continuous unconsciousness until death occurs.

But neither stunning nor killing crustaceans is necessarily a simple business when compared, for example, to fish.

This is because crustaceans have decentralised nervous systems, meaning that unlike fish, they can't be rendered unconscious with a single blow to the head.

To "spike" a lobster to death, again unlike fish, you have to pierce the body in more than one spot.

So the best ways to achieve a quick death are, according to animal welfare charity RSPCA Australia:

More details from RSPCA Australia

For Prof Elwood, the major concern is not the domestic cook or even restaurant kitchens, but major food processing plants, where animals are commonly dismembered without being killed.

He also says labelling crustaceans with relevant welfare information could help consumers make informed choices.