Last Updated on March 23, 2023 by Jeremy

Somehow after the extinction of dinosaurs and Pangea splitting up faster than a boy band, kelp came to be – between 5 and 23 million years ago during what if referred to as the Miocene era.

Forests are often thought of to be full of trees – the Boreal Forest in North America and northern Europe, the Rainforest in South America, the Black Forest in Germany – but did you know that there are forests underwater too?

Below will describe the kelp forest animals and plants and explain how diverse this interesting ecosystem truly is.

Kelp Forest Animals and Plants:

Ecosystem – a biological community of interacting organisms and their physical environment

What is Kelp? Kelp is described as “marine algae belonging to the order Laminariales“ and are considered highly diverse both structurally and functionally.

It is not a plant, but rather a heterokont – algae that provides a physical substrate and habitat within the kelp forest ecosystem.

Description of Kelp:

The body of an individual organism is called a thallus, or body, and the structure composition of the thallus is defined by 3 structural units:

1. Holdfast – this is a root-like mass that anchors the thallus to the ocean floor
2. Stipe – similar to a plant stalk or mushroom stem, it extends vertically from the holdfast and providing a support framework for other morphological features
3. Fronds – blade or leaf-like attachments extending from the stipe and are the sites of nutrient uptake and photosynthetic activity

What is a Kelp Forest?

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Kelp forests are referred to as underwater areas with high density of kelp. They can be found in temperate, subtropic, and arctic waters along coastlines worldwide.

They are an ecosystem unlike any other with many species of kelp, animals and plants living harmoniously under the water’s surface that includes 3 guilds of kelp and 2 groups of other algae.

Levels of Kelp:

Canopy Kelps

Includes the largest of the species that may extend to float at the water’s surface.

• Macrocystis, giant kelp, which is one of the most recognized of kelp. Growing a thallus up to 60 meters (200 feet), you will find it growing along the western North American and South American coastline in the Pacific Ocean, within the archipelagos in the Southern Ocean, and sporadically around Australia, New Zealand, and South Africa.
• Alaria esculenta – is an edible seaweed also named dabberlocks, badderlocks or winged kelp and it grows to a maximum length of 2 meters off the coasts of Europe, arctic waters around Canada, Greenland and other coasts in the northern Atlantic Ocean.

Stipitate Kelps

Kelp in this guild grows in dense clusters a few meters from the ocean floor.

• Eisenia – belonging to the family Lessoniaceae, this brown alga is found in Pacific Ocean waters and is widely used in Japanese cuisine.
• Ecklonia – this perennial brown alga grows off the coast of Japan and Korea. Other species of Ecklonia can be found in shallower temperate waters in the Atlantic Ocean along Africa south as well as in the Indian ocean near countries like Oman and along the coast of western Australia.

Prostrate Kelps

These species lie near or along any of the ocean floors.

• Laminaria – there are 31 species belonging to the order Laminariales that are native to the cold northern waters in the Atlantic and Pacific oceans. There are various species that are edible and used frequently in China and commercially cultivated for algin, iodine, and mannitol for use in a range of applications.

The 2 guilds of algae found in the benthic assemblage:

• other algal species (filamentous and foliose functional groups and articulated corallines for example)
• sessile organisms

*Encrusting coralline algae covers directly and extensively over geologic substrate.

Friend or Foe of the Kelp Forest

Like any forest growing on land, there are animals living within the shady, cool interior. The kelp forest is no different with creatures, fish and animals that either benefit the kelp or can completely destroy it.

These creatures use the kelp forest for either food or protection. Many fish (over 100 species of rockfish), invertebrates, sea urchins, marine mammals (seals, sea otters, whales and sea lions) and marine birds (gulls, terns, other shore birds, cormorants, great blue herons, and snowy egrets) balance out the diverse ecosystem.

Many of these animals use the kelp forest as a nursery to raise their young in a safe environment.

One most recognized symbiotic relationship within the underwater forest is that of sea otters and sea urchins:

Sea Urchins – FOE

There are 950 different species of sea urchins and all are globular, spiky echinoderms ranging in size from 3-10 cm (1-4 inches) covered in spikes varying up to 30 cm (12 inches).

They belong to the same family (Echinoidea) as sea cucumbers, starfish, sand dollars, and others.

Sea urchins are herbivorous and primarily feed on kelp that has been dislodged from the substrate and drifts freely along the ocean floor. They only become a foe to the forest when there isn’t sufficient supply of freely floating kelp; it then has to expend energy searching for intact thalli to feed on.

Sea Otters (Enhydra lutris) – FRIEND

The heaviest of the weasel family weighing between 14-45 kg (30-100 lbs), this mammal is also considered one of the smallest marine mammals native to coastal waters of the northern Pacific Ocean living atop the kelp canopy.

These mammals are diurnal, and when they’re tired, they wrap themselves in kelp to keep from floating away.

Preying mostly on sea urchins, otters also diversify their diet with various species of mollusks, crustaceans, and fish. One of a handful of animals to utilize tools, they have favorite rocks, which are kept in pouches, that they use to dislodge prey from rocks at the ocean floor as well as crack open shells.

Because their main diet contains sea urchins, they play a vital role in keeping urchin populations under control, but with previous over trapping in the early 1900s, over-fishing, and human interactions, numbers of sea otters have dwindled making them an endangered species. If sea otters were to become extinct, the kelp forests ecosystem would totally collapse.

Final Thoughts

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Kelp has been an important fixture in our history for thousands of years. Historians believe kelp forests aided in our ancestors in finding new land by acting as a sort of “highway”.

With most species being edible, it gives us minerals and vitamins that are beneficial to a healthy body. To learn more about which vitamins and minerals are obtained by consuming kelp, visit this website:

Kelp Benefits: Boost Your Health with Seaweed (healthline.com)

Not only is kelp excellent for our body’s health, but kelp forests are also popular with scuba-diving and kayaking enthusiasts who want to immerse themselves in the underwater ecosystem consisting of fish, kelp, invertebrates, sea urchins, marine mammals, birds, and other marine creatures.

Thank you for enjoying this article. Please feel free to leave a comment or question about kelp forests animals and plants.

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