The American lobster, Homarus americanus, is a large marine crustacean inhabiting the North Atlantic coast of North America, ranging from Labrador down to North Carolina. As one of the largest invertebrates in the region, it plays a significant role in the benthic, or seafloor, ecosystem. This species is an opportunistic omnivore, functioning as both a predator and a scavenger within its cold-water, rocky habitat. The lobster’s diet is diverse and changes significantly over its life, reflecting its adaptability to available food sources.
Primary Food Sources for Adult Lobsters
The adult American lobster is an opportunistic feeder whose diet is heavily dominated by other bottom-dwelling invertebrates. Mollusks form a substantial part of its food intake, with species like mussels and clams being readily consumed. The lobster’s powerful claws are specifically adapted to crush the hard shells of these bivalves, accessing the soft tissue inside.
Echinoderms, such as sea urchins and sea stars, are also regular prey items for the mature, benthic lobster. Their diet includes marine worms, specifically polychaetes, which are often unearthed from the sediment. Other crustaceans, including smaller crabs and even juvenile lobsters, are incorporated into the diet, with cannibalism occurring in the wild, particularly among recently molted or vulnerable individuals.
Lobsters also consume small fish and decaying organic matter. Their diet is highly flexible and varies regionally based on the most abundant prey. For instance, the consumption of larger rock crabs increases notably as the lobster grows into a larger adult size.
Foraging Methods and Feeding Habits
The American lobster is primarily a nocturnal hunter, emerging from its shelter in rocky crevices or burrows to forage under the cover of darkness. This activity pattern minimizes the risk of predation from larger fish and marine mammals. To locate its food, the lobster relies heavily on its sophisticated sensory system rather than sight.
The four small antennules on its head are used to “smell” the water, detecting chemical cues released by potential prey and carrion. Tiny sensing hairs, or chemoreceptors, cover the lobster’s body and are dense on its walking legs, allowing it to taste the substrate as it moves. Once food is detected, the lobster employs its specialized, asymmetrical claws for processing.
The larger, blunter claw, known as the crusher claw, is used to apply immense force to break open the shells of hard-bodied prey like mollusks and crabs. The slimmer, sharper claw, called the cutter or ripper claw, is used for tearing and shredding softer tissues. Food is then passed to the mouthparts by the walking legs, which also have taste sensors, before being moved to the stomach. The lobster’s digestive system includes a structure known as the gastric mill, which contains three grinding surfaces that mechanically chew the food before digestion begins.
Diet Shifts During Development
The American lobster’s diet undergoes a complete transformation as it progresses from a free-swimming larva to a bottom-dwelling adult. The earliest life stages are planktonic, drifting in the water column for several weeks before settling to the seafloor. During this phase, the tiny, newly hatched larvae are carnivorous and feed exclusively on small zooplankton.
A foundational crustacean species, Calanus finmarchicus, is a highly nutritious and significant component of the larval diet. As the post-larvae settle and transition to the benthic environment, they begin to consume smaller versions of adult prey. Early juveniles, which are initially restricted to sheltered areas, often consume soft-bodied organisms and smaller bivalves.
As the lobster grows and its shell hardens, its diet shifts to include more robust, hard-shelled prey that requires greater crushing power. The high-energy demands of frequent molting also influence consumption. Lobsters often eat their own recently shed exoskeletons to recover lost calcium and other minerals.