Resembling the tall canopy of an old-growth forest, blades of bull kelp tower in thick groves under Northwest seas.

Drift near a patch in a kayak or canoe and you’re likely to spot these seaweed giants by their buoyant bulbs, which allow them to float.

Like plants on land, these kelp rely on photosynthesis to survive, absorbing sunlight from above through their leaflike blades. To attach themselves to the ocean floor, bull kelp stretch upwards from a holdfast, a root-like structure that attaches to rocks.

Growing to a height of as much as 130 feet within a single annual season, bull kelp fronds provide shelter and nutrients for more than 1,000 marine life species. Relying on its thickets, which stretch from Alaska to central California, are salmon, herring, sea otters, cormorants and kelp crabs, just to name a few.

As undersea kelp forest cover rapidly declines along the northern coast of California, conceding much of its ground to large patches of purple sea urchins, some groups are seeking protected status for these undersea trees.

With increasing ocean temperatures and changing ecosystem compositions, it’s difficult to tell what the future holds for bull kelp, but for now, it’s still quite common to find its signature bulbs washed up onshore.