California sea lions in the kelp forest off San Miguel Island, California Channel Islands. Growing off the Pacific coasts of Russia and California are kelp "forests". Kelp is a kind of seaweed (a form of algae) anchored to the seabed. In some places, the kelp can grow tens of metres in length. Fish, sponges, sea anemones, starfish, sea snails and lobsters all live off fragments of kelp. They in turn are prey for larger animals, such as sea otters, seals and sea lions.
Kelp soaks up nutrients from the water around it, so it has no need of roots. Instead, it has a claw-shaped foot, called a holdfast, that anchors it firmly to the seabed. Occasionally ripped apart in storms, kelp can grow back as quickly at a rate of 50 centimetres (20 inches) a day, eventually reaching lengths of up to 80 metres (about 260 feet). It must reach the sunlight at the surface—essential for its survival.
Kelp has many sword-like leaves, called blades. At the base of these blades are ball-shaped pods of gas called "bladders". These help the kelp to stay upright in the water.
Kelp can grow as quickly as 50 cm (20 inches) a day, eventually reaching lengths of up to 80 m (about 260 ft).
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