Seals are a diverse group of semi-aquatic marine mammals in the family Phocidae. They are distinguished from the similar sea lion and walrus groups by the lack of external ear flaps and the presence of fur, among other features. Seals primarily live in the oceans but are known to spend a considerable amount of time on land or ice for purposes such as breeding and molting.
Some species of seals, like the Elephant Seal, are impressive divers. Elephant seals have been known to dive up to 2,000 meters 1,24 miles deep and can stay submerged for up to two hours, which is the longest known duration among seals
The deep-diving ability of elephant seals is not only a testament to their individual strength and endurance but also offers valuable insights into the largely unknown environment of the deep sea. Researchers often attach tracking devices to elephant seals to collect data about the depths of the ocean that would otherwise be difficult to reach.
Seals use their sensitive whiskers to detect prey. These vibrissae can pick up on the vibrations and movements in the water caused by fish and other potential meals.
This is known as hydrodynamic detection.
The whiskers of seals are highly sensitive and can detect minute changes in the water. When a fish swims, it creates a trail of turbulent water, known as a wake. Even after the fish has moved away, this wake can linger for several seconds or even minutes.
Seals are able to pick up on these wakes using their whiskers. They can detect the movement and direction of the wake, which allows them to track the path of the fish. Some research suggests seals can even determine the size and shape of the prey that created the wake, as well as the distance to it.
This capability is particularly important because seals often hunt in conditions where their vision is limited, such as at night or in murky water. Their whiskers allow them to detect and capture prey in these challenging conditions.
While many mammals’ whiskers are round, seal whiskers are often flattened or beaded in shape. This is believed to reduce the self-generated noise as the seal moves through the water, enabling them to better pick up on the signals from other creatures. This is a great example of how animals evolve to suit their specific needs and environments.
Seals go through a process known as molting where they shed their old fur and skin to make way for new growth. Some species experience a catastrophic molt where they shed their entire layer of skin and fur at once.
Molting is a natural process for seals, allowing them to replace old, damaged fur and skin with new growth. However, the manner and timing of molting can vary significantly among different species of seals.
Many seal species undergo what’s called an annual molt, where they shed their fur gradually over a period of weeks. This usually takes place after the breeding season. During this time, seals spend more time on land and less time in the water, which helps speed up the molting process.
However, some seal species, like the elephant seal, experience a more dramatic process known as catastrophic molt. During this process, seals shed their entire outer layer of skin and fur within a relatively short period of time, sometimes as quickly as a few weeks. This molting process is called catastrophic not because it’s harmful to the seals, but because of the dramatic, sudden change in appearance it causes.
One of the reasons for this molting process is the need to maintain the insulative and hydrodynamic properties of the fur and skin. Over time, these can be degraded by factors such as exposure to sunlight, seawater, and general wear and tear. By shedding the old fur and skin and replacing it with new growth, seals can maintain these important properties.
It’s also worth noting that molting requires a significant amount of energy and nutrients, so seals typically need to build up their fat reserves beforehand. This is one of the reasons why the timing of the molt is usually after the breeding season, as it allows seals to focus their energy on one major physiological event at a time.
Male Weddell seals have been known to make incredibly complex vocalizations. These calls can have as many as 34 different types of sound, including trills, chirps, and whistles.
They’re considered one of the most vocal of all pinnipeds the group that includes seals, sea lions, and walruses.
These complex vocalizations primarily occur during the breeding season. Male Weddell seals produce a range of underwater calls as a part of their courtship and territorial behaviors. The calls can include trills, chirps, whistles, and many other types of sound, with some researchers identifying over 30 distinct call types.
The complexity of these calls is thought to serve several functions.
The calls could potentially attract female seals or advertise the male’s fitness as a mate.
The calls might also serve to warn other males away from the seal’s chosen territory.
The complexity of the calls may allow individual seals to be recognized by their unique vocal patterns.
Interestingly, the vocalizations of Weddell seals can even extend beyond the range of human hearing, into ultrasonic frequencies. Research into these remarkable animals’ calls is ongoing, as their full purpose and function are still not completely understood.
What is clear, though, is that the rich vocal repertoire of Weddell seals is another example of the incredible diversity and complexity of animal communication systems.
Seals, while they might appear clumsy or slow on land due to their body structure, are incredibly agile and fast in the water. Their bodies are designed for streamlined movement in water, with a smooth, rounded shape and strong flippers that make them efficient swimmers.
The Dusky Dolphin and the Common Dolphin seals, for instance, can reach top speeds of 23 miles per hour when chasing prey or escaping predators. To put that into perspective, that’s comparable to the top speed of a running domestic horse.
It’s important to note that these high speeds are not typically maintained over long periods, as it would be too energy-consuming. Instead, these bursts of speed are generally used during hunting or when a quick escape from danger is necessary.
On land, seals move by a variety of methods, such as by wriggling their bodies and pushing forward with their flippers, or bouncing along on their bellies. While this can be somewhat slow and awkward compared to their movement in the water, it is still an effective way for them to get around on land when necessary.
In essence, seals are an excellent example of an animal that has become highly specialized for life in a particular environment, demonstrating incredible speed and agility in the water despite their somewhat awkward movement on land.
Some cold-water marine animals, including certain species of seals, have developed an amazing adaptation that allows them to survive in frigid waters. This adaptation is often referred to as antifreeze proteins or antifreeze glycoproteins in their blood.
These antifreeze proteins bind to small ice crystals in their bodies, preventing the crystals from growing larger and causing damage. This allows the seals to maintain their body temperature, even when swimming in water that’s below freezing. This is particularly important for Arctic species like the ringed seal, which live in some of the coldest waters on Earth.
However, it’s important to clarify that while this adaptation can help protect seals from the cold, it doesn’t make them immune to all the effects of freezing temperatures. Seals still rely on a thick layer of blubber for insulation and warmth, and they can still suffer from the effects of extreme cold if they are exposed for too long without protection.
Seals are known to have relatively large brains compared to their body size. This is often associated with higher intelligence and cognitive capabilities. Seals, like many other marine mammals such as dolphins and whales, display a wide range of complex behaviors and problem-solving abilities that suggest a high level of intelligence.
For example, seals have been shown to have excellent memory, capable of remembering tasks and commands taught to them over extended periods. They can also exhibit impressive problem-solving skills and can be trained to perform complex tasks.
This trainability and intelligence are one reason seals have been used by military organizations for various purposes. For example, the U.S. Navy has a program where they train sea lions and dolphins to perform tasks such as retrieving lost equipment, identifying underwater mines, or spotting intruders in the water.
This level of intelligence in seals, as in other large-brained mammals, is likely linked to their complex social structures and behaviors. These require advanced cognitive abilities to navigate. For instance, many seal species display complex mating behaviors, have intricate hierarchies, and use various forms of communication, all of which require significant cognitive abilities.
