Penguins are flightless birds, or avifauna. They used to fly in the past, but it is thought that they evolved and stopped flying. Instead, they became good at swimming & diving.

The South American fur seal lives mainly on the Pacific side of South America.

It looks like it has bones in it, but it is made of hard feathers.

Actually, they only grow beards when they are babies. It is a legacy of the dolphins' ancestors' life on land. It disappears when they grow up, but only the pores remain.

It is said that it is the closest to spiders in terms of classification.