【明報專訊】California sea lions belong to a group called pinnipeds (鰭足類). There are three families of pinnipeds: seals (海豹), sea lions (海獅) and walruses (海象). Pinnipeds are mammals, just like humans. They nurse their babies with milk. Sea lions are sometimes mistaken for seals. However, there's an easy trick to tell their difference. Look at the ears — sea lions have ear flaps (外耳殼) on the sides of their heads while seals only have tiny ear openings.

Chatty animals

California sea lions can be found in coastal regions of northeast Pacific, such as Canada, United States and Mexico. They like to rest together on beaches or bare rocks. Often, they travel in large noisy groups and communicate both vocally and through body language. They can bark, growl and even roar. Different vocalisation is used for territory guarding, and for females to identify their pups among the group.

Underwater food fest

The diet of California sea lions comprises an amazing variety of fishes and sea animals like squids (魷魚) and octopuses. Chunky food is brought to the surface and chomped into pieces before it is swallowed. They eat an average of 12 kilograms per day, which is about 6% of their body weight. California sea lions are excellent hunters. They can stay underwater for up to 40 minutes with their nostrils that can pinch closed automatically. Although California sea lions usually hunt alone, they sometimes form hunting groups and work together to herd schools of fish into tight formations to make them easier to catch.

A summer filled with pups!

California sea lions' breeding season falls in summer. During summer of the following year, females usually give birth to one single pup. It will be nursed within an hour of its birth and stay with its mum for 4 to 8 months. Between the age of 3 and 5, the pup will reach maturity.

Marine conservation is counting on you

Although California sea lions are not considered in danger, they are facing a lot of difficulties due to climate change and marine debris (海洋垃圾) like other marine animals. Fishing gear and plastic waste discarded in the ocean can entangle these animals. Pollutants in agricultural runoff (water from farm fields which usually contains fertilisers and pesticides) and urban sewage can also poison their food sources and habitat. To protect California sea lions and other wildlife underwater, dispose your rubbish properly and do not let it enter the sea!

Text & photos: Ocean Park Hong Kong

■Glossary

growl (v) 低吼

automatically (adv) 自動地

entangle (v) 纏住

sewage (n) 污水

[Smarties' Power English 第219期]