Ocean plants are a peculiar group of marine autotrophs or the primary producers under water. They convert the solar energy into carbon-rich biomass, which fuels aquatic animals. Little is also known about ocean plants, and they are still awaiting to be fully understood by scientists. In fact, it is said that we know more about the moon and Mars than the Earth’s ocean floor. To spotlight these underrated organisms, we will feature some common plants that live in the ocean.
What Is an Ocean Plant?
Ocean plants refer to autotrophic marine beings–those that possess chlorophyll and can process their own food through photosynthesis. They typically dwell near the ocean surface or seashores to take the most advantage of solar power.
What Plants Live in the Ocean?
Algae and Seagrass are the two main groups of plants that inhabit aquatic environments. Algae are sometimes considered as plants because they have green pigment. However, they are protists, representatives of another kingdom or biology that can be further split into several groups, depending on the cell characteristics. The other group comprises seagrasses, which are true plants in the ocean anchored into the seafloor. They have true roots, stems, and leaves, unlike algae, which is a composite of single or various cells.
How Many Plants Are in the Ocean?
At least 72 species of seagrasses are known to exist. Algae is a bit larger group, consisting of about 30,000 to a million species, most of which are yet to be discovered. Some multicellular algae, such as seaweeds, are often confused with seagrasses but are differentiated by the presence of real flowers, leaves, stems, and roots.
Types of Plants In The Ocean
For the purpose of featuring other plant-like living entities that might be of interest in fishkeeping and underwater gardens, we include algae as an ocean plant aside from the true marine plants:
- Phytoplankton. They are microscopic single or multi-celled under sea lives capable of generating food through photosynthesis, like plants, often found on the ocean surface. Although they have autotrophic habits, they are considered protists and not plants. Diatoms, dinoflagellates, and cyanobacteria are classified under this group.
- Corals. A coral is a composite of several polyps–the animal that lives in the rocky and branching reefs, dotting shallow to deep ocean floor. The group includes several hard and soft corals, including red sea whip brain coral.
- Sea anemones. Despite their floral-like features, it is excluded from the plant life in the oceans. Related to corals, they are grouped under the Phylum Cnidaria. One excellent example is the giant plumose anemone.
- Seaweeds. The plant-like seaweeds are macroalgae, typically floating on the surface or anchored to the seafloor. Kelps, red algae, and sargassum fall under this category.
- Seagrasses. Ocean plant life, specifically in shallow seas, is often dominated by seagrasses. They are food for many invertebrates. Seagrasses are also often cropped as ornamental plants in aquariums. Manatee grass, turtle grass, and shoal grass are some of the common ocean plants names under this group.
Are Corals Plants, Rocks, or Animals?
Corals are animals composed of various polyps that live inside the skeleton, giving it a branch-like or phytoid appearance. While some can team up with algae, the fact that they belong to heterotrophic life form, species that cannot photosynthesize and rely on feeding on others, disqualifies them from being in the plant kingdom. Despite being animals, they play an irreplaceable role in the marine ecosystem. Corals protect coastal areas and create fish refuges.
The Most Fascinating Plants That Live In the Ocean
Plants in ocean are so diverse. They feature an outlandish anatomy that is not so common for their relatives. To put it simply, we have placed them in three categories, mainly based on the most common morphological features:
If you wonder what plants live in the ocean, the answer is true plants are limited to the seagrass family. Regardless of not being a real plant, some deep-sea creatures have flower-like features that make them look like an underwater ornament:
- Sea Anemone. Popularized by Disney's Finding Nemo, the sea anemone has a symbiotic relationship with clownfish. The orange-colored fish provides nitrogen from its excrements, and in return, the tentacled creature becomes a hiding spot for the fish against predators.
- Green Sea Anemone. Another flower-like living thing common under the sea floor biome is the green sea anemone. It generally occurs in the intertidal zones of the Pacific, including Panama, Alaska, and California. When hit by direct sunlight, it displays its brightly-colored green tentacles reminiscent of its name.
- White-Plumed Anemone. Found in the Pacific Ocean from Alaska to California, this feather-like anemone is one of the largest of each kind, reaching approximately a meter. It features white fluffy tentacles that resemble ostrich plumes when retracted. While it is generally white, other salmon or orange-tinged specimens are not uncommon.
There is a great chance that plants that live underwater that you commonly see are macroalgae. Although they are not real plants, they possess spectacular leaves that are important in various industries:
- Kelps. They are actually algae and not true plants. However, despite the taxonomic status, they are still worth mentioning for their stunning foliage. These algae usually reach a height of 250 m, stretching from the sea floor to the ocean surface.
- Sargassum. Named after the Sargasso Sea in the Atlantic, Sargassum is another species of brown algae closely related to kelps found in tropical and temperate waters. They are one of the cultivated seaweeds used for extracting pharmaceuticals, especially in traditional medicine.
- Muskgrass. The muskgrass might also be confused as a real terrestrial counterpart, but it is also a freshwater algae that can inhabit brackish saline marsh. They have vine-like bodies with whorled spikes that can grow up to 2 meters tall.
- Shoal grass. Commonly occurring in saline marshes and knee-length coastal areas, the shoal grass is the only flowering plant on the list. It reproduces asexually through its rhizomes and sexually by releasing seeds from the flowers. They are vulnerable to boat anchors, so think twice before boarding a ship!
The ocean vegetation is dominated by pretentious plant-like creatures that are actually animals! However, since they are typically featured in aquariums and ocean parks, we include them in the following list:
- Red Sea Whip. The soft-bodied red sea whip belongs to the coral family hosted by the Atlantic Ocean. They are often characterized by their flexible whip-like branches where the polyps are attached.
- Purple Coral. Varying in shades of violet and blue, the purple coral is a favorite aquarium insert due to its showy color. They are also relatively easy to keep, adding another reason for its popularity.
- Red Algae. With over 7000 species, the red algae is one of the most notable tidal seaweeds for its stand-out color. Most of them are multicellular and can be found floating on the surface. Many red algae are cultivated for medicinal purposes.
Interesting Facts on the Ocean Plant Life
Under the sea plants have some abilities that might surprise you. Here they are:
- With over a thousand existing sea anemones, only 10 of these inhabit the shallow, warm waters of the tropics. Only a few of them are compatible with its partner species of clownfish.
- The true plants thriving in an aquatic habitat have interesting pollinating tricks. Instead of evolving bright-colored petals to attract flowers, they produce fairly unattractive flowers, which are mainly pollinated by the tides.
- To avoid dislodgement from the strong seafloor currents, seagrasses have adapted to develop deep and strongly anchored root systems called rhizomes.
- The sea anemone lives symbiotically with a zooxanthellae algae, which provides food, and as a gesture of gratitude, it can live rent-free inside the anemone’s gastrodermal cells.
- Like their inland counterparts, seagrasses are also grazed by sea cows, which are also not a distant relative of the mammalian bovines.
- Corals feed at night when the phytoplanktons and zooplanktons migrate vertically in the presence of light.
- Anemones are like jellyfish that can sting. It is a good idea not to touch them when they are on the water surface during low tides.
- Algae account for more than 50% of the breathable oxygen. It's more than land trees can produce.
What Is the Most Beautiful Underwater Plant?
The most beautiful underwater flora, not limiting the definition to a proper plant, is definitely the sea anemones. While they are related to animals, they are brightly colored and make a stunning aquarium display.
How Do Plants Survive in the Ocean?
Adaptive features help underwater plants thrive. They study the shallow seafloor to get good access to sunlight. The rhizomes anchor the plants to prevent flushing by the current, and these plants have a high saltwater tolerance.