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Ocean Plants: Marine Gardens You’ll Find Underwater

Ocean Plants: Marine Gardens You’ll Find Underwater

Written by Scuba.com
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Updated on June 8, 2023
Seagrass on ocean floor, ocean plants underwater

There are thousands of different types of plants found in the ocean, and all of them are affected by the amount of available sunlight, salinity levels, and the temperature of the water. Ocean plants are rarely talked about, but with 70 percent of the world covered in water, they play a vital role in oxygenating oceans around the world, protecting certain species of aquatic animals from predators and outside elements (including human activities), and helping animals thrive by being their primary food source.

What is an ocean plant?

There are five types of ocean plants: phytoplankton, red algae, kelp, seagrass, and sargassum. These sea plants fall into three groups: euphotic (sunlight), disphotic (twilight), and aphotic (midnight). Which group they are in is dependent on how much sunlight they need to survive and grow. Ocean plants come in all shapes and sizes, from single-celled organisms to multi-celled trees.

What plants live in oceans?

Within these marine plants are a variety of ocean plants that live in all corners of the seas in a multitude of sizes and colors. Some include: sea lettuce, sea anemone, irish moss, manatee grass, wakame, waterwheel plant, and sugar kelp.

Common Types of Ocean Plants

There are basically two categories of plants living in our ocean’s waters: those that float freely through the water, and those that are directly rooted into the ocean floor. Floating plants live near the surface of the water. Rooted plants, on the other hand, must acquire sunlight to survive, so they live in shallow waters near the shore.

Let’s discuss the four common types of floating and rooted plants that live in the ocean:

Phytoplankton

Phytoplankton ocean plants
Photo by NOAA on Unsplash

Phytoplanktons are probably the most common ocean plants. It’s a term that represents a variety of sea plants including algae and diatoms. Phytoplanktons float on the surface of the water and soak up energy from the sun in order to procreate. Not only are phytoplanktons the most common marine plant, they are one of the most numerous organisms on the planet. As they die, they become food for the next generation. This is how they continue to thrive in such large numbers.

Kelp

Kelp plants in water
Photo by Shane Stagner on Unsplash

Kelp beds commonly live throughout colder ocean waters. As a form of algae, kelp grows along rocky coastlines at depths of 20 to 90 feet, clinging to rocks with their root-like structure or staying afloat through the use of tiny flotation bulbs. This oceanic plant thrives on sunlight and it can often grow up to 250 feet in length, making it the largest marine plant in the world.

Red Algae

Red Algae in ocean
Image via Shutterstock

Red algae have populated the warm, tropical waters of the world for more than 500 million years. It gets its unique coloration from phycoerythrin, a pigment that absorbs blue light and reflects red light. Similar to kelp, red algae is rich in proteins and vitamins. This makes it a popular food source for countries throughout Asia.

You’ll also find a unique type of red algae, the coralline algae, which are made of very fine filaments and are hard as the rocks that they grow on to support the structure of coral reefs.

Seagrass

Seagrass on ocean floor
Photo by Benjamin L. Jones on Unsplash

Seagrass is a rooted plant that requires a lot of light to thrive along the shallow waters of our world’s coastlines. There are many common types of sea grass, including manatee grass, turtle grass, and shoal grass. All of these are varieties of a land plant that has evolved over the years to survive in salt water.

It is also a popular food source for crabs and lobsters throughout the temperate marsh waters where it commonly grows. Not only does seagrass greatly contribute to the task of oxygenating the oceans, but it also releases pollen from its flowers to pollinate other ocean plants. It provides a protective habitat for small marine life and serves as food for some species of reef fish.

This makes seagrass one of the most important plants found in the ocean.

Sargassum

Sargassum gulfweed on ocean beach
Photo by Thor Tryggvason on Unsplash

Sargassum, also known as gulfweed or sea holly, is a floating ocean plant that plays an integral role in the early lives of many marine species. It is characterized by its brownish-green coloration, dense, bushy fronds, and berry-like gas-filled bladders that keep it afloat.

The bladders’ floating nature keeps the plant up at the surface of the water, better enabling photosynthesis where it can be closer to the sun and allowing juvenile sea turtles to turn to it for food and shelter as they mature and eventually make the long trip back home.

Sargassum is so abundant in a gyre of the North Atlantic that it has been dubbed the Sargasso Sea. Some marine species in the Sargasso Sea are found nowhere else in the world!

Ocean Plants: Frequently Asked Questions

Are there plants in the deep ocean?

There are no plants in the deep ocean. Due to the lack of sunlight, photosynthesis is not possible at those depths. Instead, the deep ocean is home to unique ecosystems supported by chemosynthetic bacteria and other organisms adapted to survive in extreme conditions.

How to plants survive in the ocean?

Plants that survive in the ocean, such as seaweed and seagrasses, have adaptations to overcome the challenges of their marine environment. They can extract nutrients from the water, use specialized structures to anchor themselves, and have adaptations to withstand wave action, salinity variations, and low light conditions.

Conclusion

Ocean plants are part of some of the most important ecosystems on the planet. It is imperative that we all do our best to protect and take care of our marine gardens.

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Our team of experts and scuba diving pros at Scuba.com share their knowledge of the underwater world.