The anatomy of a crustacean

 

Although crabs and lobsters look different, they share a common physiology. All crustaceans have bilaterally symmetrical bodies covered with a thick exoskeleton.

 

Like other arthropods, adult crustaceans have segmented bodies and jointed legs. The segments are usually grouped into a recognizable head, thorax, and abdomen. The head bears two pairs of antennae, usually one median eye and two lateral eyes, and three pairs of biting mouthparts – the mandibles and two pairs of maxillae.


In crustacean anatomy, a ganglion is a biological tissue mass that is part of the animal's nervous system. For instance, a lobster has 12 ganglia running from its brain down the length of its body. To successfully kill a crustacean quickly, all the ganglia must be destroyed. It is not possible to kill crustaceans by trauma to just one central location, as with vertebrates.


With the gradual heating method, lobsters take up to 15 minutes to die

 

This highlights the inherent difficulty in how to humanely kill a crustacean. For instance, many chefs kill shellfish by spiking the ganglia or splittling the animal in half. These methods require speed and precision to minimise suffering. It is easy to miss the ganglia, and the chef has to be careful not to injure himself in the process.

 

Another widely used method is to boil shellfish alive. Lobsters placed in boiling water take two to three minutes to die. If the gradual heating method is used, they can take 15 minutes to die.


Crustastun destroys the ganglia by delivering an electrical current that passes along the back of the animal and through the ganglia and heart. The animal dies in just a few seconds, with minimal suffering.

 

lobster anatomy

 

Section of a lobster highlighting
the ganglia and heart

 

crab anatomy

 

Section of a crab highlighting
the ganglia and heart