Sea anemones are fascinating creatures and almost everyone gets their introduction to them by way of tide pools or aquariums. While they’re often described as beautiful sea flowers, they’re not flowers at all but are boneless, predatory invertebrates that share family ties with corals, jellyfish, and other hydrozoa. While the majority of anemones spend their lives anchored to a solid structure, a few species are free-swimmers.
When habitat conditions deteriorate, anemones can detach and move using flexing locomotion to travel to a new home. Some even bury themselves in the sediments of the seafloor for further protection from predators and elements. But that’s just some of their interesting behaviors. Find out more about anemones below.
Facinating Facts About Sea Anemones
While there are more than 1,000 different species of sea anemones, they tend to have similar characteristics. First, they have three main parts: a pedal disc (base or foot), a cylindrical body, and tentacles coming out of a central mouth.
The body of a sea anemone can grow as wide as six feet, and its tentacles are typically poisonous so it can paralyze and effectively capture prey before feeding it into its mouth. All it takes is a very slight touch to trigger the tentacles to shoot out filaments that will inject toxins into the prey. But, like jellyfish, not all anemones are harmful to humans—or fish.
Some species of sea anemones can live as long as half a century, and they spend most of it migrating—by swimming, sliding along, or even floating upside down with the help of its special gas chamber within the pedal disc. That is, when they’re not staying in one place to eat zooplankton, fish, mussels, shrimp, worms, and other small crustaceans and marine life forms.
Sea anemones are among the most famous examples of marine life forms that exhibit symbiotic relationships in the ocean. Through mutualistic symbiosis, sea anemones benefit from clownfish, which help ward away predators, get rid of parasites, and offer nutritious waste in exchange for meal scraps and protection within the anemone’s tentacles. They say clownfish are able to become immune to anemone stings due to the special mucus coating on their bodies.
Mutualism also allows these flowers in the sea to get sugar and oxygen for green algae (through photosynthesis) in exchange for providing protection and helping expose green algae to light. Some hermit crabs also use sea anemones to cover themselves for camouflage.
You can see them in both cold and warm waters, but most species prefer the tropics. In fact, you’ll find the largest of the sea anemonies in tropical, coastal waters. And finally, they get their name from the terrestrial anemone flower that looks a lot like it.
Unique Species of Sea Anemones
Below, we’ve featured a few notable members of this beautiful family.
Adhesive Sea Anemone (Cryptodendrum Adhaesivum)
The adhesive sea anemone can be found in the waters of Australia, southern Japan, the Coral Triangle, Thailand, and the Red Sea. They are so named because of their extremely sticky tentacles, and while several species appear similar to the adhesive, they have unique characteristics that set them apart.
The adhesive has two separate types of tentacles: five or more short, stocky tentacles are found within the mouth, resembling a glove somewhat, while the rest of the body’s tentacles are long and flowing. These tentacles will differ in color, usually in pairs of pink/yellow, grey/blue, or brown/green.
There are many other species of anemones that have sticky tentacles, but some of them have detachable tentacles while the adhesive sea anemone tentacles will remain intact.
Bubble-Tip Sea Anemone (Entacmaea Quadricolor)
The bubble-tip sea anemone resides in the same waters as the adhesive anemone, as well as in East Africa. Again named for the appearance of bubbles (or bulbs) on the tips of its tentacles, these anemones are some of the most commonly found abiding in symbiotic relationships with various species of fish. They are generally colored light brown, with reddish tips on white bulbs.
Bubble-tip anemones like to anchor deeply into holes or crevices, where only the tentacles can be willfully exposed while hunting. They are truly one-of-a-kind in appearance.
Beaded Sea Anemone (Heteractis Aurora)
True to its name, the beaded sea anemone bears bead-shaped formations along the length of its tentacles, which can be sticky to the touch. Their coloration is typically more subdued; hues of brown, green, and purple are observed on the uppermost part of the tentacles, while the bases are sometimes a mottled red or orange.
The beaded anemone may attach itself to a buried object, where it can then retract its tentacles completely into the seafloor if threatened.
Magnificent Sea Anemone (Heteractis Magnifica)
Presumably named for its impressive size and the contrasting colors of the column and tentacles, the magnificent sea anemone is the most commonly photographed anemone in the world. They are commonly found in and around the waters of French Polynesia, East Africa, and Australia.
Its characteristic blunt-end tentacles are generally subdued colors of green and brown, while the column exhibits much brighter shades of purple, blue, green, red, and white. It also prefers an exposed habitat, which is why it often attaches itself to a sturdy chunk of coral or a boulder and forms a large cluster.
Interestingly, this species of sea anemone can retract its tentacles almost completely into the column, leaving only a small tuft of tentacles on display.
Have you seen these kinds of sea anemones during any of your dives? Which one is your favorite?