Invertebrates
Lobster
Nephropidae and Palinuridae · also called lobsters, rock lobster
A lobster is an armoured animal that walks the sea floor at night, feels its way by smell and touch because its eyes are nearly useless in the dark, and — if it is a clawed lobster — keeps growing and rebuilding its body for its entire life with no obvious sign of getting old. A big one may well be more than a hundred years old.
Overview
“Lobster” covers two only distantly related crustacean families. The clawed lobsters (Nephropidae — American and European lobster) have a big crushing claw and live in cold and temperate seas. The spiny or rock lobsters (Palinuridae) have no claws but long spiny antennae and live mostly in warm water. All are bottom-walking carnivores and scavengers that shelter in crevices by day and forage at night.
Not ageing, but not immortal
Clawed lobsters show negligible senescence — they do not visibly weaken or slow with age, and they keep the DNA-protecting enzyme telomerase in their tissues. But they still die, and very old lobsters are usually defeated by the sheer energy cost of moulting an enormous shell, or by infection through a cracked one, or by a predator or a trap first.
Growth by moulting
A lobster’s shell cannot stretch, so it backs its whole body out through a split behind the head, swells with water, and hardens a larger shell over days — hiding, soft and defenceless, the whole time.
Odd colours and long marches
Lobster blood is copper-based and pale blue, and about one in two million has a vivid blue shell. Caribbean spiny lobsters march across the open sea floor in single-file queues of dozens each autumn, heading for deeper winter water.
Status
Lobsters as a group are Not Evaluated. The American lobster is abundant in the Gulf of Maine but has collapsed in southern New England as the water warms; the European lobster is recovering under trap and size limits; and several spiny lobster fisheries are fully exploited or overfished.
Lobster: common questions
Do lobsters really live for hundreds of years?
They can live a very long time, but the biggest claims are exaggerated. Clawed lobsters show negligible senescence, meaning they do not visibly age, and they keep growing throughout life, so a large lobster is genuinely old, with the heaviest recorded animals estimated at somewhere around 50 to 140 years. The commonly repeated figure of a specific lobster being 140 years old is a rough estimate rather than a measured age, because lobsters have no reliable growth rings. Very old lobsters do eventually die, often because moulting an enormous shell becomes too energy-costly and exhausting, or the old shell cracks and lets in infection, or a predator or a trap gets them first.
Is it true that lobsters are immortal?
No, and this is a widespread misunderstanding of the term negligible senescence. Lobsters do not have a built-in ageing clock that steadily weakens the body the way mammals do, and they maintain the DNA-protecting enzyme telomerase in their tissues, so an old lobster can be as vigorous and fertile as a young one. But they still die, and in the wild the great majority are eaten, caught, or killed by disease long before old age is a factor. Even the oldest survivors are eventually defeated by the physical demands of moulting a shell that has grown to the size of a small dog. Not ageing is not the same as not dying.
What is the difference between a lobster and a crayfish?
They are close relatives and built on the same plan, an armoured body, a fanned tail, walking legs, and a large front pair of claws. The main difference is size and habitat. Lobsters are large marine animals of the sea floor, with the American and European clawed lobsters reaching several kilograms. Crayfish, also called crawfish or yabbies, are smaller freshwater animals of streams, rivers, lakes, and swamps, usually a few centimetres to about 15 centimetres long. A crayfish is essentially a small freshwater lobster, and the two are so alike that crayfish are sometimes marketed as freshwater lobster and one Tasmanian giant freshwater crayfish reaches lobster size at up to 6 kilograms.
Do lobsters feel pain when they are cooked?
The scientific consensus has shifted toward yes, or at least that it is likely enough to matter. Lobsters and other decapod crustaceans have a nervous system, produce stress hormones, and show behaviours consistent with pain, such as grooming and guarding an injured limb and learning to avoid places where they were harmed. On that basis, several countries and jurisdictions, including Switzerland, Norway, New Zealand, and the United Kingdom, now recognise decapods as sentient in animal welfare law and require or recommend humane killing methods, chiefly rapid chilling followed by swift mechanical destruction of the nerve centres, rather than dropping a live lobster into boiling water.