Sometimes it becomes a topic on TV news, and sometimes it becomes a model for anime.
The cute seal is very popular because it is often seen at aquariums and is well known. However, did you know that it has a deep relationship with humans?
Let’s take a look at the ecology and lifestyle of seals!
～ Basic information. ～
They mainly inhabit a wide range of seas from the Arctic Ocean and the Southern Ocean to the North Atlantic and North Pacific.
They are a diverse group of animals, ranging from small sizes like the Ringed Seal to very large sizes like the elephant seal.
Their faces are round and their bodies are plump and chubby. They have five fingers on their limbs and are shaped like fins because they have flippers.
Seal fur has been used as a fur since ancient times because it has high heat retention.
Seals also have excellent diving abilities in the sea.
There is no clear distinction between males and females, but some species can be distinguished by their body size or whether or not they have breasts attached to females.
The breeding season is basically around March-April, but depending on the species, it may be in January. It is said that seals give birth to about 1-2 offspring at a time.
Their lifespan is about 30 years, and some seals have lived up to 34 years.
Since seals are carnivorous, they mainly eat seafood such as squid and fish. Depending on the species, they may also prey on penguins or other seals.
How can seals dive into the ocean for a long time?
There are animals such as otters and penguins that dive into the sea to search for food, but they do not have as high diving abilities as seals.
On the other hand, depending on the species, seals can dive for up to 120 minutes and 1,700 meters. So why are their diving abilities so excellent?
Although there is no clear reason, it is thought that a substance called “myoglobin” may be involved.
Myoglobin is a pigment protein that can store oxygen until it is used in muscles. Humans also have myoglobin in their bodies, but it is said that seals have about 10 times more myoglobin in their bodies than humans. Therefore, it is speculated that they can stay in the sea for a long time.
What is the difference between seals and sea lions?
They have flippers on their limbs and their faces and bodies look similar…
At first glance, seals and sea lions look very similar, but these two species have clear differences.
One is whether they have auricles or not. Seals only have holes in their ears, but sea lions have auricles like humans.
The other is the way they walk. They look the same at first glance, but they walk differently when you look closely. Both seals and sea lions have tail fins, but seals move by sliding on their stomachs because their tail fins cannot be folded back and forth.
On the other hand, sea lions’ tail fins can be folded back and forth, so they can move well while moving their tail fins.
If you see them at an aquarium, please compare them.
*Auricles are part of the visible ear, including earlobes that can be pierced.
Where does the seal get its name?
In English, it is called ‘seal’, but in Japanese it is called ‘azarashi’. This time, I will introduce the origin of why it is called ‘azarashi’ in Japanese.
You may not have thought about it deeply, but now that you mention it… don’t you wonder why they are called seals? In fact, there are several reasons that have been speculated.
For example, there are some varieties of seals that have black spots all over their bodies. When people saw these spots as “aza” and added the old suffix “ra” and then added “shi”, they started calling them “azarashi”.
There is also a theory that when seals are written in kanji as “umihyou”, which is a phonetic equivalent, the character for “hyou” is associated with the animal “hyou”, so there is a story that they are animals with spots like leopard patterns living in the sea.
Although such theories have been considered, there are often no clear evidence for the origin of animal names, not just for seals. However, it’s fun to imagine what might have really happened while expanding your imagination.
Do seals really have fur?
At first glance, seals appear to have smooth bodies, but when you touch them, you can confirm that they have short hair growing all over their bodies.
Because they are moderately oily, their fur is said to be of high quality among animal furs.
Seals often live in cold seas, so this fur is very useful for protecting their bodies from the cold. In addition, large amounts of subcutaneous fat are also essential for cold protection.
By the way, baby spotted seals have a cute white body. There is a good reason for this too. Spotted seals give birth on drift ice, and their fur turns the same color as the surrounding snow and ice to make it harder for enemies to find them and protect themselves.
And this baby fur changes into adult spotted seal fur after about three weeks.
What is a harem of seals?
Generally, when seals breed, they tend to be monogamous, but the Southern Elephant Seal breed is a little different.
It is said that they create a group called “harem” and leave offspring in it.
However, not all Southern Elephant Seals can form a harem. After a battle between males, only the strongest male who survives can become the top of the harem.
Males are single from birth until they are 1 to 12 years old. Then, around the age of 13 or 14, a turning point comes. Here comes the chance to create a harem for the first time.
After the harem competition, the winning male lives with about 100 females. And more than half of them are females and repeat breeding, leaving offspring.
Males are also desperate to leave their own offspring, so surviving in the harsh natural world may be more difficult than we think.
Do seals have good hearing?
As mentioned in other Q&A, the ear of a seal is designed with only a hole. However, have you ever wondered if the hearing ability of a seal without an auricle is high?
Surprisingly, the hearing ability of seals is said to be not very good.
To explain in easy-to-understand numbers, humans can hear sounds ranging from 20 to 20,000 hertz. On the other hand, seals can hear sounds ranging from 300 to 5,000 hertz. With this alone, seals may be thought of as animals with poor hearing ability. However, seals have the ability called “echolocation”.
Echolocation is the ability to locate food and determine the size of objects using ultrasound. By the way, dolphins also have this echolocation ability.
Are seals a problem as vermin?
Tamachan, a Bearded Seal that suddenly appeared in the Tama River one day and became a model for anime characters, is a cute and popular seal.
However, did you know that there is a problem with seals causing damage?
In fact, marine animals such as seals and walruses are having a serious impact on fishing in Hokkaido.
To explain fishing damage in an easy-to-understand way, it means that fish that we humans have caught with nets or were trying to catch are eaten by seals first.
We are trying to prevent this by using fireworks to drive them away, but sometimes we have to exterminate them.
Animals living in the sea are also doing their best to survive, and we humans also have to live our lives, so it seems difficult to solve this problem peacefully.
Type of seal.
・Southern elephant seal.
・Northern elephant seal.
・Hawaiian monk seal.
・Mediterranean monk seal.
・West Indian monk seal.
オスとメスはどちらが得か?(祥伝社新書) 2016/12/2 稲垣 栄洋