A single giant kelp (or Macrocystis) can grow up to 60 metres long in a single year — 30 metres of stipe and 30 metres of frond. At it's peak growth period, it can grow over a metre in less than two days. Giant kelp is anchored to the seafloor by roots, aptly called a holdfast.
You'll probably be surprised to hear that kelp is not a plant: it's a protist. That's partly because early in their complex life cycle they are a free swimming organism with a tail. Giant kelp can live for up to 10 years.
Like a forest of trees, kelp grow in large numbers together and provide food, shelter and habitat for an interdependent web of creatures, great and small. Kelp forests provide shelter and habitat for billions of creatures, some starting life, others just ending.
For example, herring lay their eggs on the kelp, and when they hatch, the young herring mill about under the kelp canopy, eating tiny plankton and often getting eaten themselves. Seals, sea lions, nudibranchs, sea snails, wolf eels, jellyfish, rockfish and a multitude of other species also make use of kelp forests. Even whales are known to find shelter in kelp forests during storms, with the thick kelp acting as a buffer from waves and currents.
Kelp in British Columbia comes in different shapes and sizes. Bull kelp, or Nereocystis, is a fast-growing annual (it dies every year) known for the large bulb on the end of its "tail." Anyone who has walked along a Pacific Coast beach will have seen one of these long whip-like tails.
The kelp's bulb contains carbon monoxide, helping it float near the surface and allowing its blades to collect sunlight. It's so efficient at photosynthesis that it is one of the fastest-growing organisms on the planet, growing by up to 60 centimetres per day during mid-summer.