The Life Cycles for Lobsters

The lobster begins life as an egg. The tiny egg, no bigger than the head of a pin, is carried inside the mother's body for nine to 12 months before being fertilized and expelled with many others at once. The female excretes a gluelike substance that attaches them to the mother's swimmerets. Here they remain for another nine to 12 months until hatching. Once hatched, the baby lobsters float to the surface to begin their larval stage.

Lobster larvae float at or near the surface of the water, feeding on the plankton around them. They remain in the larval stage for four to six weeks. They will molt four times in this stage, with each molt bringing about significant changes to their sizes and appearances.

After molting for the fourth time, the young lobsters are heavy enough to sink to the ocean floor. There, they seek shelter in cracks and crevices until they have grown large enough to dig their own shelters. They will remain in these shelters, expanding them as necessary, for 25 molts -- usually five to seven years -- until they reach adult stage.

Once adults, weighing about 1 pound, they are free to roam the ocean floor. Lobsters continue to grow their entire lives, but at a slower rate. It is difficult to determine the exact age of a lobster, but based on average yearly growth it is believed they regularly live more than 50 years, perhaps as long as 100 years. Males molt only once a year and females every two years. With each molt the lobsters may increase their lengths as much as 15 percent and their weights by as much as 40 percent. They are solitary animals who stake out a territory and drive all others lobsters away. The only time they allow other lobsters into their territory is for breeding.

After female lobsters reach sexual maturity they can mate every other year. Copulation can occur only immediately after a female molts while her shell is still soft. Shortly before a fertile female is to molt, she will find a male's den and sit outside of it, releasing pheromones so he does not chase her away. Once convinced she is not a threat, the male will allow her into his den. She will remain there until she mates and her new shell hardens. The male's sperm is stored in a receptacle within the female's body for up to a year, until her eggs are mature. The eggs pass through this receptacle and are fertilized on the way out of her body.