Seals are one of the most adorable sea creatures. With their puppy-like features and behaviors, they are rightfully named "sea dogs."
These seemingly harmless creatures are one of the top marine predators. They possess remarkable hunting capabilities. The Leopard Seal, in particular, is an apex predator in the Antarctic that eats fish, penguins, and other seals.
Other interesting facts about seals are their swimming and diving abilities. Elephant Seals are skilled divers capable of going as deep as 1,500 feet in length and staying submerged for long periods.
Read on to learn more about these exciting creatures' unique adaptations and other fun facts.
Seals are marine mammals, and the collective term that refers to three distinct families of pinnipeds: Earless Seals or True Seals (Phocidae), Eared Seals (like sea lions and fur seals in the family Otariidae), and Walruses (family Odobenidae). There are 33 species of seals, each with physical traits and behaviors that make them distinct3.
True seals lack external ear flaps, have short front flippers, and are well-adapted to icy environments. Eighteen species are true seals, some of which are the Southern Elephant Seal and the Caribbean Monk Seal.
Eared seals, on the other hand, have external ear flaps and long front flippers for efficient movement on land and are skilled swimmers. The walrus, a member of the Odobenidae family, possesses long tusks and is found in Arctic regions, relying on sea ice for various activities.
Seals, particularly certain species of eared seals, have earned the nickname "Sea Dogs" due to their physical resemblance to canines. Their sleek bodies, elongated snouts, and expressive eyes bear similarities to dogs.
Moreover, seals' playful and social behavior further reinforces the comparison. Seals are eager to investigate and interact with divers or humans in their natural habitats.
They may approach with curiosity and friendliness, making eye contact, mimicking movements, and engaging in playful behaviors such as swimming in circles or gently nipping at fins.
Seals have been a subject of folklore and maritime traditions throughout history, further solidifying their connection to the term "Sea Dogs." Tales of seals interacting with sailors, aiding lost fishermen, or even transforming into humans have contributed to their association with dogs.
Dolphins are also famous for their playful interactions with humans. Get to know more about them by reading these dolphin facts.
Did you know that there's a seal species that's as big as a basketball court? A male Southern Elephant Seal can weigh 8,800 pounds and measure up to 16 feet long, making them the largest among the seal species.
It lives in the Eastern and North Pacific Oceans as well as the Antarctic Ocean. Consequently, the smallest seal species are the Ringed Seal and Galapagos Fur Seal, weighing 110 pounds and measuring around 5 feet long.
The former is well-suited for life in Arctic regions, spending time under ice and navigating through narrow breathing holes. Meanwhile, Galapagos Fur Seal is endemic to the Galapagos Islands in Ecuador.
Seals are semi-aquatic marine mammals that inhabit a wide range of habitats. They adapt to life in both saltwater and freshwater environments. Seals reside in oceans, seas, lakes, rivers, and coastal areas.
Seals prefer colder climates and commonly inhabit polar regions like the Arctic and Antarctica. These seals (like the Earless Seals) develop thick fat and dense fur layers to withstand freezing temperatures.
Other seal species inhabit temperate regions, including coastal areas along the shores of continents and islands. They often use rocky coastlines, sandy beaches, or ice floes for resting, breeding, and giving birth to their young.
While most of these cute creatures reside in marine environments, one species thrives in a freshwater habitat. The Baikal Seal (Pusa sibirica) is the only seal species that exclusively inhabit freshwater environments. This earless seal is endemic to Lake Baikal in Siberia, Russia (hence the name).
Seals are well-adapted for life in the water. Their streamlined bodies and flipper-like limbs allow them to move smoothly through the water1. They have a thick layer of fat (blubber) that keeps them warm and provides energy during times of scarcity. Seals can hold their breath for a long time underwater thanks to efficient oxygen storage in their muscles and blood.
These skilled swimmers use their flippers and body movements to navigate effectively. The Leopard Seal, for example, can reach speeds up to 18 mph.
Despite their adorable appearance, seals are voracious hunters. They primarily consume fish but can also hunt down other marine creatures (like squid and mollusks). Depending on the seal species and habitat, seals may feed on a wide range of prey, including small fish like herring, sardines, and anchovies, as well as larger species like salmon and cod.
Furthermore, as brilliant marine animals, seals employ effective hunting tactics. For example, the Australian Sea Lion (Neophoca cinerea) uses bubble netting.
They release a stream of bubbles while swimming underwater, creating a circular wall of bubbles around a school of fish. This bubble net is a barrier and confines the fish within a smaller area. The seal can easily capture multiple prey in a concentrated area thanks to the bubble net.
Next in our top seal facts is their impressive diving ability. Species like the Weddell and Elephant Seals can dive over 5,000 feet. That is equivalent to stacking five Empire State Buildings on each other!
These amazing dives are made possible by physiological adaptations. Seals have high levels of myoglobin, which allows them to store oxygen in their muscles for underwater adventures4. Some seals can hold their breath for up to two hours, which sets them apart from most other marine mammals.
How do they do it? Like Hooded Seals, they slow down their heart rate, called bradycardia, to conserve oxygen. Furthermore, they have collapsible lungs and specialized spleen to prevent nitrogen narcosis and decompression sickness during deep dives5.
Contrary to what its name suggests, the Crabeater Seal (Lobodon carcinophaga) does not eat crabs. Despite its misleading name, this unique seal species has a specialized diet primarily consisting of tiny crustaceans called Antarctic Krill.
Crabeater Seals have elongated, slender snouts and specialized teeth, allowing them to filter krill out of the water efficiently. Their numerous close-set teeth interlock, creating a sieve-like structure that enables them to strain out krill while expelling water.
Male seals mate with multiple females during the breeding season. They compete for females by being aggressive and making sounds. Dominant males establish territories and defend them against rivals. After establishing their territory, they mate with receptive females on land or ice.
Female seals have specific mating seasons when they are ready to mate. After mating, female seals go through a gestation period lasting from months to over a year, depending on the species.
Most seal species observe delayed implantation, where fertilized eggs wait before attaching to the uterine wall. This delay allows for synchronized births when conditions are suitable for raising offspring.
Leopard, Gray, and Elephant Seals have a polygynous mating system, where dominant males mate with multiple females. Breeding occurs during the Antarctic summer, and females give birth to a single pup on ice floes or land. The pups are born with a dark coat, and their mothers nurse them until they are independent enough to hunt.
Following their "sea dog" nickname, baby seals are also called "pups." Depending on the species, pups are born on land or ice. Seal pups often have fluffy fur and big, innocent-looking eyes that capture the hearts of many.
To support the pup's growth, mothers nurse them with high-fat milk. Seal milk is extremely rich in fat and protein6. Hooded seal mothers produce milk with over 60 percent fat, surpassing human breastmilk's fat content (around 3-5 percent).
Seal mothers only breastmilk for four days. Due to milk's fat content, pups double their weight after this period. The short weaning period is necessary for the pups' survival. On the other hand, Harp Seal pups' survival depends on their first ten days.
Seal pups, born on floating ice, are very vulnerable to predators, especially polar bears, killer whales, and even other seals. That's why they rely entirely on their mothers for food and protection during their early stages of life.
Seal-pupping seasons vary depending on the species and location, but they often coincide with favorable environmental conditions when food is abundant. During this time, beaches or ice floes become bustling nurseries as mothers gather to give birth and rear their young ones.
One fascinating fact about seals is that they have a remarkable range of sounds they use to communicate. From barks to grunts and enchanting songs, their vocalizations serve essential purposes. They use this to recognize each other (especially for mothers and pups), assert territories, attract mates, and warn others about potential dangers. Their communication abilities are complex and fascinating to observe2.
Seals have an impressive range of vocalizations, especially underwater. Species like the Weddell seal can produce over 30 distinct sounds, which helps them communicate effectively in the water, where sound travels far. The call of Harbor Seal pups can even reach a kilometer.
Even their above-water calls, though more straightforward, are still effective for communication. Seals have excellent hearing and can recognize and respond to different individuals' vocalizations.
Seals have played a vital role in human societies, especially in polar regions. Indigenous communities have relied on seals for their nutritious meat, warm fur from fur seals for clothing and blankets, and seal oil for various purposes like fuel, lubricant, and paint base. This functional dependence on seals reflects the enduring relationship between humans and these animals.
On an emotional level, seals have captivated people worldwide with their grace, beauty, and fascinating behaviors. Their charming expressions and playful nature have made them beloved subjects for photographers, artists, and wildlife enthusiasts.
In many coastal cultures, like the Inuit in the Arctic, seals are significant in local mythology and folklore, often associated with mystical qualities and shapeshifting abilities. The deep admiration for seals has also led to the growth of seal-focused ecotourism, providing opportunities for visitors to observe these magnificent creatures in their natural habitats.
Seals are in danger of disappearing forever. Some seal species have gone extinct, like the Caribbean Monk Seal and Japanese Sea Lion. The Mediterranean and Hawaiian Monk Seal are also close to extinction.
For example, people are destroying their homes and polluting the environment. Climate change is also causing problems. Melting ice puts seal pups (especially ringed seals) at higher risk as they no longer have hiding places. Climate change also reduces food availability.
During the 19th and 20th centuries, hunting and commercial seal dealing heavily impacted seals. Today, bycatch, the unintentional capture of seals in fishing gear, is a significant concern, especially for species sharing habitats with commercial fisheries. Traping in fishing nets can injure or kill seals.
Organizations worldwide focus on rescuing, rehabilitating, and releasing injured and orphaned seals into their natural environments. Facilities like the Marine Mammal Center, the National Marine Life Center, and the Seal Rehabilitation and Research Centre are crucial in ensuring the well-being and survival of these vulnerable marine mammals.
With the help of dedicated volunteers and professionals, these organizations respond to reports of distressed seals, assess their condition, and provide the necessary care for them to thrive in the wild. Injured seals receive treatment and medication, while orphaned pups receive specialized care. Moreover, experts gradually introduce fish to their diets.
Additionally, these organizations closely monitor the seals' progress and carefully plan release events to maximize optimal conditions. After release, the organizations track the seals using tags or visual identification to learn more about their challenges and improve conservation efforts.
What are your favorite seal facts? Remember to share it with your friends!
Related: To further explore the animal kingdom, check out some of the other animals that start with S.
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Rogers, T. L., & Cato, D. H. (2002). Individual variation in the acoustic behaviour of the adult male leopard seal, Hydrurga leptonyx. Behaviour, 139(10), 1267-1286.
Berta, A., Churchill, M., & Boessenecker, R. W. (2018). The origin and evolutionary biology of pinnipeds: Seals, sea lions, and walruses. Annual Review of Earth and Planetary Sciences, 46, 203-228.
Kooyman, G. L., Castellini, M. A., Davis, R. W., & Maue, R. A. (1983). Aerobic dive limits in immature Weddell seals (Leptonychotes weddellii). Journal of Comparative Physiology B, 151(2), 171-174.
Zapol, W. M. (1987). Diving Adaptations of the Weddell Seal. Scientific American, 256(6), 100–105.
LeBoeuf, B. J., & Ortiz, C. L. (1977). Composition of Elephant Seal Milk. Journal of Mammalogy.
Chinny Verana is a degree-qualified marine biologist and researcher passionate about nature and conservation. Her expertise allows her to deeply understand the intricate relationships between marine life and their habitats.
Her unwavering love for the environment fuels her mission to create valuable content for TRVST, ensuring that readers are enlightened about the importance of biodiversity, sustainability, and conservation efforts.
Fact Checked By:
Mike Gomez, BA.