Lobsters undergo a remarkable transformation from microscopic larvae to recognizable juveniles. Their diet and feeding strategies adapt significantly as they develop, influenced by their changing bodies and marine environments.
The Larval Menu
Lobster larvae are tiny, free-swimming organisms that primarily consume microscopic marine life. They are omnivorous, feeding on zooplankton like water fleas, copepods, crab larvae, and eggs. They also ingest phytoplankton such as diatoms, dinoflagellates, and filamentous algae. Recent research confirms that a key zooplankton species, Calanus finmarchicus, is a significant part of the diet of newly-hatched lobsters, often consumed in higher proportions than its availability in the wild might suggest.
Spiny lobster larvae, known as phyllosoma, are also generalist predators in the water column. Their diet includes gelatinous zooplankton like arrow worms (chaetognaths), cnidarians, and fish larvae. They also consume salps and other soft-bodied arthropods. Lobster larvae are equipped with specialized morphological structures that aid in capturing their prey. However, early larval stages are less efficient at feeding, sometimes taking nearly an hour to consume larger prey like Calanus.
The small size of larval lobsters, often less than a centimeter, and their microscopic, soft-bodied prey make traditional diet analysis challenging. Researchers have increasingly used advanced molecular techniques, such as DNA sequencing of gut contents, to identify specific prey items. These methods reveal a broader range of consumed organisms, including worms and fish eggs, and even single-celled organisms like microalgae that might be food for their prey.
From Larva to Juvenile: Shifting Diets
As lobsters progress through their larval stages, they undergo a significant metamorphosis, transitioning from a planktonic existence to a benthic, bottom-dwelling life as juveniles. This shift in habitat directly influences their food sources and feeding behaviors.
Early juvenile lobsters are often shelter-bound, residing in crevices and burrows. They initially rely on small prey carried to them by water currents, such as amphipods and isopods. As they grow and gain strength, these young lobsters begin to venture outside their shelters to forage. Their diet expands to include a wider array of bottom-dwelling organisms.
Juvenile lobsters become more predatory, consuming mobile invertebrates like crabs and gastropods. They also feed on sessile filter feeders such as mussels and clams, echinoderms like sea urchins and starfish, and various marine worms. Lobsters possess a crusher claw designed to break open the shells of their prey, while their cutter claw is used to tear flesh. The development of their gastric mill, or “stomach teeth,” during larval stages enables them to process more substantial food items as they mature. Their diet can also include bait from lobster traps, acting as an opportunistic food source.
Environmental Influences on Feeding
The feeding success and dietary composition of young lobsters are significantly shaped by environmental conditions. Factors such as water temperature, salinity, and oxygen levels play a role in their metabolic needs and the availability of food. The overall abundance of food sources in their specific habitat is a primary determinant of their diet.
Warming ocean temperatures, particularly in regions like the Gulf of Maine, can lead to a reduction in the populations of key plankton species. A decline in Calanus finmarchicus, for example, has been linked to a decrease in juvenile lobster populations, suggesting that food limitation impacts larval survival. Ocean acidification, resulting from increased carbon dioxide absorption, can hinder the ability of lobsters to form strong shells, potentially affecting their feeding efficiency and overall health.
Water temperature influences a lobster’s metabolic rate and oxygen consumption; higher temperatures increase their oxygen demand, especially after feeding. Low oxygen levels (hypoxia) can also impact their ability to feed and survive. Contaminants, such as certain agricultural pesticides, have been shown to disrupt the health and growth of planktonic lobster larvae. These environmental stressors can alter the types and quantities of food available, thereby influencing the feeding behaviors and developmental success of baby lobsters.