Why dedicate an article to sea anemone facts?
For scuba divers, anemones are, if not one of their favorite species, yes, a reference; a source of admiration; and many times, a place to look closer to find different creatures. The anemones look like open flowers as if they were centerpieces sprinkled on the counters of a colorful banquet: the one provided by the reef.
Sea anemones are the stars of this article. We will learn from them…
Actiniaria is the anemone’s scientific name.
1. If you wonder if an anemone is a plant or an animal? The answer is: sea anemones are invertebrate animals, although they look like plants. So much so that many people believe they are marine plants.
2. The sea anemone gets its name from the terrestrial anemone. These are indeed plants.
3. These animals, although without skeletons or brains, are tremendous predators.
4. There are around 1200 species of sea anemones around the world. Some of the showiest anemones in the Caribbean are:
Sun Anemone (Stichodactyla helianthus)
Giant Caribbean Anemone
(Condylactis gigantea)
Colonial White Anemone
(Palythoa caribbea)
Spiral Anemone
(Bartholomeaannulata)
5. Sea anemones can have multiple colors.
6. They are polyps that spend most of their lives attached to reefs or rocks. Their generally cylindrical bodies have an adhesive foot and tentacles surrounding the mouth.
7. Just because their feet are sticky doesn’t mean sea anemones can’t move. These animals can walk and even swim.
8. When the sea anemone is in the larval stage, it swims.
9. The most common behavior is that once the anemone is attached to a surface, it remains in the same place for its entire life. However, should the environmental conditions require it, they can slide their pedals and even detach to let themselves go with the current. Some species can even swim using their tentacles.
10. The Sea anemone’s tentacles are stinging. They have cnidocytes. These cells have paralyzing neurotoxins, like jellyfish.
11. When a sea anemone prey approaches, the tentacle moves closer, immobilizing it with the toxin and moving it closer to the mouth.
12. A sea anemone fun fact is that its mouth is also its anus.
13. The anemone’s tentacles can self-regenerate like starfish do and are also tremendously plastic and flexible. It means that they can extend, contract, twist, bend, and even retract within the foot of some anemones.
14. On the other hand, sea anemones do not have a brain or specialized sensory organs. Indeed, they have a nervous system, but it is not centralized.
15. The diet of sea anemones is composed mainly of zooplankton, invertebrate animals, small fish, mollusks (mussels, clams), and crustaceans (shrimps and prawns). But anemones can have different sizes. The largest ones can eat bigger prey.
16. Sea anemones do not appear to have many predators due to their formidable defense system. However, some studies point to one type of nudibranch as the number one enemy of anemones, the gray slug (Aeolidia papillosa).
17. Anemones can exist in all marine habitats. They can live from the tropics to the icy waters of the Arctic. Neither can a specific depth be identified. Although most anemones prefer to live in shallow waters with nutrient-rich currents, some specimens have their home at great depths.
18. A remarkable sea anemone fact is the symbiotic relationships they establish with their environment.
19. Thanks to “Finding Nemo,” the public learned that clownfish live in anemones, but they are not the only ones. They also harbor some shrimp. How is this possible? Don’t anemones sting them?
Yes, they do, but both have strategies to avoid the poison. In fact, if a shrimp leaves its anemone to move to another, its new home will sting them until they develop its adaptation strategy. It consists of rubbing their bodies against the mucosa of the anemone itself.
20. Clownfish, meanwhile, already have a mucous membrane covering their scales.
21. This association that unites the anemone with the clownfish and certain shrimp is called mutualism. It is not a dependent relationship, they can live without each other, but they make life easier.
While the clownfish gets protection from predators and undigested food debris, the anemone gets rid of parasites and nutrients from fish excrement. The shrimp, for their part, protect the anemone against fireworms and other nudibranch.
22. Thanks to the symbiotic relationship that sea anemones establish with algae, they can take advantage of sunlight. As they are animals, anemones do not photosynthesize. However, there are unicellular algae called zooxanthellae, which live inside anemones.
Zooxanthellae do a similar job for corals. With their photosynthesis, they provide the anemone with sugars and oxygen. On the other hand, the algae are protected from predators and obtain food from the catabolites of the sea anemone (mainly phosphorus and nitrogen).
23. Many anemones participate in the primary production of coral reefs by hosting zooxanthellae.
24. According to scientists, an anemone’s lifespan can exceed one hundred years. With more than a century of life and their reproduction rates, the anemones are not threatened.
25. Depending on the species, sea anemones reproduce sexually or asexually.
26. The anemone’s asexual reproduction can be by bipartition (a division of the animal that produces two separate individuals) or by budding (the parent specimen generates buds, which grow and give rise to new anemones)
27. As a general rule, the sexual reproduction of anemones begins with the release of sperm from the males.
28. In some species, the female also releases the ova; in others, fertilization happens inside the female anemone.
29. After larvae hatch, they float in the water until they settle on the seabed.
30. Within sexual reproduction, we find hermaphrodite sea anemones. In other words, they can change their sex and take the male or female role.
You can learn more sea anemone facts if you observe them. This does not mean that you put them in an aquarium. It is better to come and see them for yourself in their natural habitat. Drop a line and tell us when you are coming.
