Lobsters undergo molting, or ecdysis, to facilitate their growth. This process involves shedding their rigid outer shell, which is necessary for them to increase in size and develop. Molting is a physiological event that prepares the lobster to shed its old exoskeleton and emerge larger. It is a recurring event throughout a lobster’s life, from its earliest larval stages to its adult years.
Why Lobsters Molt
The primary reason lobsters molt is to grow. Lobsters possess a hard, external covering called an exoskeleton that does not expand. As the lobster’s soft tissues grow, they eventually outgrow the confines of their current exoskeleton. Shedding the old shell allows the lobster to increase its body size. Molting also enables lobsters to regenerate lost or damaged limbs or antennae. This process is essential for their development, particularly as they transition through various life stages.
The Molting Timeline
The frequency of molting changes throughout a lobster’s life. Younger, juvenile lobsters molt more often due to their rapid growth, sometimes multiple times a month in their earliest stages. For instance, within their first five to seven years, lobsters may molt up to 25 times. As they mature, the molting frequency decreases; adult males typically molt about once a year, while females may molt once every one to two years. In colder waters, an adult lobster might go two years without molting, as lower temperatures slow their growth rate.
Environmental factors influence when molting occurs. Water temperature is a primary determinant, with warmer waters generally leading to more frequent molting and faster growth. Most molting activity takes place during the warmer months, typically from early July to early September, but this can vary by species and location. Food availability also plays a role, as a sufficient food supply is necessary to fuel the energy-intensive molting process and subsequent growth. Light cycles and the presence of other lobsters can affect molting timing.
The Molting Process
Before shedding, a new, soft shell begins to form underneath the old, hard exoskeleton. The lobster’s body starts to absorb water, which causes it to swell and create pressure against the old shell. This internal pressure helps to split the old shell, usually along a seam between the carapace and the tail. The lobster then backs out of its old shell, a process that can take around 30 minutes, though the actual withdrawal from the shell may be as quick as 8 to 10 minutes.
Immediately after emerging, the lobster’s new shell is very soft and paper-thin, making it vulnerable to predators and environmental stresses. This “soft-shell” stage is a period of rapid growth, as the lobster continues to absorb water, expanding its new, pliable shell to a larger size. Rapid calcification then begins to harden this new shell, a process that can take several weeks, with full hardening sometimes requiring 14 to 30 days. During this time, the lobster often consumes its recently shed shell to reabsorb lost calcium and minerals, which helps to accelerate the hardening of the new exoskeleton.