5.水下森林生机勃勃

Beyond the surf is an underwaterjungle.

Giant kelp supports a dynamic, chilly, theater.

Each marine tree might growup to a foot per day.

Gas bladders pull the stalks towards surface sunlight.

In stead of roots that extend into earth, kelp has "anchors" called holdfasts that grip onto rocky substrates.

Sea urchins prey upon the kelp itself.

Tooth-like plates surround on the bottom of its shell.

Urchins attack the stalk, eating through the stem.

These starfish relatives can destroy entire kelp forests.

But even the sharpest urchin spines are poor defense against rock-wielding otters.