Seals are captivating marine mammals that inhabit diverse aquatic environments across the globe. These streamlined creatures, belonging to the group pinnipeds, are known for their adaptability to both water and land. Their widespread distribution, from polar ice to temperate coastlines, hints at the variety of food sources they exploit.
Common Seal Prey
Seals are carnivorous, primarily eat marine animals. Fish are a significant portion of their diet, with common species including cod, herring, salmon, pollock, and flatfish. They also frequently hunt cephalopods like squid and octopus. Crustaceans, such as shrimp and crabs, are another important food group for many species. Some seals are opportunistic, adjusting their diet based on seasonal prey availability.
Dietary Differences Across Seal Species
The diet of seals varies considerably among species, reflecting their unique habitats and specialized foraging strategies. For instance, the crabeater seal, despite its name, primarily feeds on Antarctic krill, which makes up over 90% of its diet. This specialization is linked to the abundance of krill in the Southern Ocean. In contrast, elephant seals eat fish, squid, and octopus. Northern elephant seals also prey on rays and sharks.
Leopard seals are apex predators in their Antarctic environment, with a diverse diet including fish, squid, krill, and other marine mammals and birds. They hunt penguins and the pups of other seal species, such as Weddell and crabeater seals. Harbor seals are generalist feeders, adapting to locally available prey, including various fish, cephalopods, and crustaceans. Bearded seals, found in Arctic waters, eat bottom-dwelling invertebrates like shrimp, crabs, clams, and whelks, and demersal fish.
Adaptations for Hunting and Eating
Seals possess a suite of physical and behavioral adaptations for hunting and consuming prey in their aquatic environments. Their streamlined bodies allow for efficient movement through water, while powerful hind flippers provide propulsion.
To locate prey in murky or dark waters, seals rely on their highly sensitive whiskers, known as vibrissae. These whiskers, with numerous nerve endings, detect subtle vibrations and movements, allowing them to track prey even in low visibility. Seals have excellent underwater vision, aided by large eyes with specialized structures that gather light efficiently.
Their teeth are adapted for a carnivorous diet, with sharp canines for grasping and tearing prey. While some seals have molars for crushing harder-shelled prey like crustaceans, many swallow smaller fish whole. Deep-diving capabilities allow seals to hold their breath for extended periods and slow their heart rate significantly to conserve oxygen during dives. Elephant seals, for example, can dive over a mile deep and remain submerged for up to two hours.