THE ANIMAL FILES

California sea lion

Zalophus californianus

The flippers that drive a swim can also support a walk ashore.

California sea lions move between water and land using the same body in different ways. Foreflippers provide underwater thrust, while hindflippers can turn forward for movement ashore. Their whiskers add a sensory channel when the surrounding water carries movement as well as light and sound.[1]

Follow the evidence ↓
California sea lion
Image: marneejill · Commons · CC BY-SA 2.0
Swimming engine
Primarily the foreflippers[1]
Land movement
Hindflippers turn forward for four-limbed walking[1]
Touch
Whiskers detect underwater vibrations[1]

Stroke, then glide

The foreflippers generate thrust, with gliding between strokes. A streamlined body reduces drag, and a flexible spine assists turns. This differs from imagining the animal paddling continuously with all four flippers. The body can bend while preserving an efficient underwater shape, allowing changes of direction within a swim.[1]

A different arrangement ashore

California sea lions rotate their hindflippers forward and walk on all fours. Head and neck movements also contribute to terrestrial motion. Their appearance changes with sex and age: adult males develop a more robust neck and chest and a raised forehead crest, while females and younger animals have a more slender profile.[1]

Reading movement in water

Whiskers provide touch and detect underwater vibration. Hearing is also effective underwater. Fish, squid and octopus are important foods, taken around coastlines, the continental shelf and other feeding areas. Individuals may feed alone or gather with others, depending on food availability; some exploit hunting activity by other marine predators.[1]

A COMMON MIX-UP

Are all four flippers the main swimming paddles?

No. Foreflippers provide the principal thrust, with gliding between strokes.[1]

TRY A LITTLE REASONING

Why would whiskers remain useful when visibility underwater is poor?

Reveal the explanation

They detect physical movement and vibration in water, supplying information through touch rather than relying only on vision.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Zalophus californianus (adapted and translated; exact revision)
  2. NCBI Taxonomy — Zalophus californianus (identity and game lineage)

Last fact check:

One discovery leads to another

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