Seals are marine mammals that spend a significant portion of their lives in the ocean, yet coming ashore is a natural and necessary part of their existence. While their streamlined bodies are adapted for aquatic life, they regularly return to land for various biological processes. This dual existence on land and in water is a defining characteristic of these creatures.
Understanding Seals’ Time on Land
The duration a seal can remain out of water varies by species, age, health, and environmental conditions. Harbor seals, for instance, split their time fairly evenly, spending about half their lives on land. In contrast, larger species like northern elephant seals spend roughly 90% of their time at sea, coming ashore primarily for breeding and molting, enduring several consecutive weeks on land during these periods.
Physiological adaptations enable seals to manage their time ashore. Their thick blubber provides insulation against cold water and serves as an energy reserve during fasting periods on land. Seals also possess a specialized kidney system that conserves water and excretes excess salt, which helps them stay hydrated without freshwater intake. They can regulate their body temperature on land through counter-current heat exchange in their flippers and behaviors such as flipping sand onto themselves to cool down.
Why Seals Haul Out
Seals come out of the water, a behavior known as “hauling out,” for several essential reasons. One primary reason is to rest and sleep, conserving energy in a safe environment away from marine predators. They also haul out for thermoregulation, either basking in the sun to warm their bodies or utilizing cool, wet sand to prevent overheating.
Molting, the annual shedding of old fur and the growth of new, is another activity seals undertake on land. This process is energy-intensive and requires increased blood flow to the skin, which is more efficiently achieved in air than in cold water. Elephant seals undergo a “catastrophic molt,” shedding both fur and skin over approximately a month while on shore. Females also come ashore to give birth to their pups and nurse them, with some species like harbor seals temporarily leaving their pups on the beach to forage. Additionally, seals may haul out for social interaction within their colonies or to briefly escape aquatic predators.
Dangers of Prolonged Land Exposure
While hauling out is a natural and necessary behavior, prolonged or inappropriate land exposure can pose significant risks to seals. Dehydration is a concern, as seals do not drink freshwater and must rely on their metabolic water derived from fat reserves while fasting ashore. Overheating can also occur, particularly for species with thick blubber, as their insulation designed for cold water can become a disadvantage on warm land.
Seals on land are also more susceptible to terrestrial predators. Human disturbance is a major threat, which can interrupt their rest, feeding, and nursing cycles. Such disturbances can cause seals to expend energy by flushing back into the water prematurely, and in severe cases, can lead to mothers abandoning their pups or seals suffering injuries from stampedes. Exposure to land-based pollution or diseases also adds to the dangers seals face when ashore.
What to Do if You Encounter a Seal on Land
If you encounter a seal on land, it is important to remember that it is likely engaging in normal, necessary behavior. Maintain a safe distance, generally at least 50 to 100 yards (150 feet), to avoid disturbing the animal. Approaching or touching a seal is illegal and can cause stress, potentially separating a mother from her pup or leading to aggressive defensive behaviors from the seal.
Observe the seal quietly, refraining from loud noises or sudden movements that could startle it. If a seal appears injured, entangled, or in obvious distress, or if you are concerned about a seemingly abandoned pup, contact your local marine mammal rescue organization or wildlife authority. Do not attempt to rescue or assist the animal yourself, as trained professionals are best equipped to handle such situations safely for both humans and wildlife.