Babies on Board: How Lobsters Reproduce

female lobster with eggs
The underside of a northern lobster, (held in the gloved hand of a diver), laden with new eggs.

WHETHER WE CATCH THEM OR BUY THEM, the process of having a lobster for dinner begins with lobster eggs – the tasty crustaceans begetting more of the same in the ocean.

How lobsters reproduce is an arduous journey that takes as long as 20 months from mating to hatching. During much of that time a female lobster carries her eggs around on her underside, protecting and nourishing them.


Like their crustacean crab cousins, female lobsters have to molt, or shed their shells, in order to mate, and, like crabs, the mating males play a role in protecting them while they are in their vulnerable, unshelled state.

When a lobseterette is ready to molt and mate, she selects the bachelor she wants to mate with, usually the largest guy around, by releasing a pheromone – a chemical linked to sexual attraction – in front of his den.

The fact that she releases it in her urine sounds gross, but apparently it works for lobsters. He responds by leaving his den for a brief bout of confrontation that somehow turns to compliance. As described by Dr. Jellie Atema of the Marine Biological Laboratory, she signals her readiness to mate by raising her claws and placing them on his head.


Entering the den leads to her molting hours or days later, at which point the still-shelled male gently turns her weak, soft body onto its back with his walking legs and mouth parts. He uses his first pair of abdominal limbs or appendages, called swimmerets, to transfer his sperm into a receptacle on her body. She remains safe in the den for about a week while her new shell forms and hardens. It’s a short-lived romance. After that, they go their separate ways.

Having mated and received the male’s sperm doesn’t mean that a female lobster is bearing eggs.She may keep the sperm placed in its handy storage place for months before laying her eggs. She does so by turning onto her back, cupping her tail and pushing 10,000 to 20,000 eggs out of her ovaries, passing them through the sperm receptacle for fertilization. They’re passed along her abdomen, where a sticky substance glues them to the bottom of her tail.


Inside the eggs, embryos grow by shedding their own shells. But it’s a long process – she carries the eggs/embryos for nine to 11 months, fanning them with her swimmerets to give them oxygen and keep them clean from debris. Newer eggs are small and green, as in the photo here.

As they mature, they grow and develop a brown – even orange – color. When the time is right, she lifts her tail into the current and fans them with her swimmerets, releasing them in batches that may occur over several days. Like most sea creatures, the young are released into the current as larvae to drift with the plankton. Mama lobster diligently nurtures her eggs for months and then sets them loose to fend for themselves.

PRINCIPAL SOURCES: Marine Life of the North Atlantic, Andrew Martinez; Peterson’s Field Guide to the Atlantic Seashore, Kenneth L. Gosner; Gulf of Maine Research Institute; The Lobster Conservancy; The Lobsterman’s Page.


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