1. How Ear Flaps Tell Seals and Sea Lions Apart
Seals have ear openings, but they do not have external ear flaps, which are the parts of the ear that stick out like on humans. On the other hand, sea lions, fur seals, and Steller sea lions do have small ear flaps [1].
This means that seals belong to the "seal group," while sea lions, fur seals, and Steller sea lions belong to the "sea lion group," which is a different group [1]. It is also worth noting that walruses do not have external ear flaps [1].
2. How Sea Lions Walk on Land While Seals Slide
Members of the sea lion group can turn their hind flippers forward. Because of this, they can walk on land using all four limbs [2].
However, seals keep their hind flippers pointing backward. They cannot walk like dogs or cats. Instead, they wiggle their bodies and slide along the ground, moving somewhat like a caterpillar [2].
3. Which Animal Makes the "Aw! Aw!" Sound at Aquariums
Have you ever heard a sound like "Aw! Aw!" at an aquarium? That is the call of a California sea lion. Fur seals do not typically make that specific sound [3].
There are also differences in body size. The Steller sea lion is the largest member of the sea lion group [3]. Fur seals are generally smaller members of the sea lion group [3].
4. How Sea Lions and Seals Share the Same Ancestor
In the past, it was thought that sea lions (and walruses) evolved from bear-like animals, and seals from weasel-like animals, separately [4].
But later research on immune systems and DNA overturned that view. Today it is widely supported that all of these animals split off from a single common ancestor. Some details of how they are related are still being debated. One view is that the ancestor was an otter-like animal that lived partly in the water, something like Potamotherium of about 23 million years ago [4].
5. Why Aquariums Choose Sea Lions for Shows
Sea lions are often featured in aquarium shows. One reason is that they are smart and can learn many tricks. Another reason is that they can stand and walk on their hind legs [5].
Because seals cannot walk on their hind legs, the movements they can show in a performance are different from those of sea lions [5].
6. How Steller Sea Lions Damage Fishing Nets and Why Fur Seals Were Hunted
Steller sea lions come to the waters off Hokkaido in winter. They eat fish caught in nets and sometimes break the nets. This has become a serious problem for people who work in the fishing industry. The damage was reported to be about 2 billion yen a year in fiscal 2013 [6].
On the other hand, fur seals were hunted heavily for their fur after demand for fur grew in Europe in the 19th century, and Japan joined the hunt in the early Meiji era [6]. Because their numbers dropped sharply, Japan, the United States, Britain, and Russia signed a treaty in 1911 to protect fur seals and settle fishing disputes [6].
7. How to Tell Seals and Sea Lions Apart by Their Ears at an Aquarium
If you have a chance to visit an aquarium, look closely at the animals' ears. You can tell if they are in the seal group or the sea lion group by seeing if they have ear flaps or not.
It is also interesting to watch how they walk and which way their hind flippers point.