Back to: Kelp Farming 101

Kelp is a type of large, multicellular, marine brown algae. Algae, broadly, are a diverse group of photosynthetic aquatic organisms that live in the ocean, as well as in freshwater environments. They use chlorophyll to capture the energy of the sun and turn it into tissue to grow. It’s estimated that there are between 30,000 and 1 million species of algae in the ocean. They range from microscopic, primarily single-celled, free-floating organisms (or microalgae) to macroscopic, multicellular organisms (commonly called seaweeds). There are three main taxonomic groups of seaweeds: red (Rhodophyta), green (Chlorophyta), and brown (Ochrophyta). 

Hover over the images to see the names of common brown algae.

Seaweeds can be found all over the world along the coast in the intertidal and subtidal zone.

You’ve likely seen several hundred different species of seaweed washed up in the high tide wrack line over the course of your lifetime. Many species of kelp, including sugar kelp, grow naturally in the rocky intertidal and subtidal zones of both the Atlantic and Pacific Oceans. They thrive in cold, nutrient-rich water.

Kelps resemble plants in many ways, with long stem-like structures (called stipes) and root-like structures (called holdfasts), but they’re actually not related at all.

Unlike plants, algae cells are undifferentiated—they don’t have true leaves, roots, seeds, or a vascular system. In fact, taxonomically, they belong to entirely separate kingdoms! One of the most unique things about kelps is how fast and large they grow. They are some of the fastest growing organisms on the planet, developing rapidly from their microscopic spore phase into a mature adult in a matter of months. Depending on the species and location, an adult kelp blade may grow 20 feet long or more in one growing season, and some bull kelp can grow to over 100 feet in length.

Click on the blinking buttons to learn about the three main physical components of sugar kelp.

Different species of kelp will have different morphologies, causing them to take a variety of shapes, but they all share these three components.