Lobsters are marine creatures often associated with myths about their growth and longevity. While a common belief suggests lobsters never stop growing, this is not entirely accurate. Lobsters exhibit indeterminate growth, meaning they continue to increase in size throughout their lives, unlike most other animals that stop growing once they reach adulthood. However, this continuous growth faces significant challenges and physiological limitations that prevent indefinite growth. Their unique growth method, involving periodic shedding of their outer shell, enables this ongoing increase in size.
How Lobsters Grow
Lobsters grow by undergoing a process called molting, or ecdysis, which involves shedding their rigid outer shell, the exoskeleton. This hard, inflexible covering cannot expand, so for a lobster to increase in size, it must shed its old shell to make room for a new, larger one. Before molting, a new, softer shell forms underneath the existing exoskeleton. Hormonal changes trigger this process, causing the old shell to soften and separate from the new one.
During molting, the lobster absorbs water to expand its body, creating hydrostatic pressure that helps it break free from its old shell. The lobster then backs out of its old exoskeleton, often exiting through a split between its carapace and tail. Immediately after shedding, the new shell is soft and pliable, allowing the lobster to absorb more water and expand. The new shell then begins to harden, a process that takes days to weeks. Lobsters can also regenerate lost limbs during this process.
The Limits to Lobster Growth
Despite their capacity for continuous growth, lobsters face practical and physiological limits. Molting is an energy-intensive and risky endeavor, becoming more difficult as a lobster grows larger and older. Larger lobsters require more energy to shed their old shell and form a new one. This can lead to exhaustion, with some lobsters dying from the metabolic demands of the process.
During the period immediately after molting, when their new shell is soft, lobsters are vulnerable to predators. They are also susceptible to infections from microorganisms and pathogens, as their soft shells offer less protection. Failure to successfully extract themselves from the old shell can also be fatal. While lobsters do not stop growing in a biological sense, the cumulative risks and energy requirements associated with molting mean that very old and very large lobsters are rare in the wild. An estimated 10-15% of lobsters die annually due to molting complications.
What Influences a Lobster’s Size
A lobster’s ultimate size is not solely determined by its age; environmental factors significantly influence its growth rate. Water temperature is a primary factor, with warmer waters accelerating metabolic processes and leading to more frequent molting. Conversely, colder temperatures can slow down growth and molting frequency. This means a younger lobster in a warm, abundant environment might outgrow an older one in a less favorable setting.
Food availability also plays a crucial role, as sufficient nutrition is necessary to support the energy demands of molting and tissue growth. Lobsters with access to ample food resources can molt more frequently and increase their size substantially with each molt. Habitat quality, including factors like population density and suitable shelter, can also affect growth rates. Injuries can impact growth, sometimes leading to reduced growth rates or shorter intermolt periods.