Anemonemowhat?

I love anemones. I'm not afraid to say it, it's true, and more importantly I know how to say it! The pronunciation is "uh-nem-uh-nee," for all those interested. I know there's a million different ways people try to say it, but if you want to impress your lady and guy friends (you do), then you're going to want to pronounce it correctly. And for good reason, because anemones are awesome. They're these slimy, gooey, water filled bags of joy with harpoon tipped appendages that capture prey with a vicious vendetta. They're the living offspring of spider webs and Venus flytraps if spider webs could eat your face while you walked into them and Venus flytraps were equipped with motion-sensing harpoons. They're the insatiable stomachs of the oceans, and you need to love them. Unfortunately, I find that many people don't actually know what an anemone is, or how to even identify them. That changes today, minions. Today I want to talk about anemones and their noodley appendages.

Heteractis magnifica with an ocellaris clownfish (www.boundless.com).

Look, I've seen Finding Nemo, ok?

An older woman was in the shop the other day, and staring at the aquarium like I normally do, she assumed I had some idea about what was going on (poor lady). So, she walked up to the tank, pointed at what my cousin and his girlfriend refer to as a "sea pancake" and said, "Now I know the rest of this stuff is anemones, but what is THAT?" That's when I realized that unless you're an aquarist or an ocean fanclub member, you probably don't know what anemones actually look like. Ok, maybe that's not fair. You might know they have tentacles and that Nemo lives in one, but aside from that there's not much discrimination between wavy things underwater.

Tentacles? Check! Is it stuck to a rock? Check! ANEMONE!

However, there's a lot more to anemones than flimsy appendages. For instance, the picture above is actually a spaghetti finger leather, and no you can't eat it. You're not entirely off the mark by thinking it's an anemone, though. Actually, clownfish (sometimes called anemonefish due to their symbiotic relationship with anemones) will treat corals like this one as if it were an actual anemone. They'll swim all through it, rubbing their little bodies seductively all over them, and challenge any fish foolish enough to swim by.

Clarkii clownfish doing her thing in a spaghetti finger leather

I promise not to give you a lesson in phylogenetics, but there are few distinct things that separate anemones from corals. For one, anemones can move around on their own. Their "foot," also called a pedal disc, is what they use to move around the aquarium. It's very similar in function to a snail's foot. If you can envision an anemone as an upside down jellyfish with a snail's foot where the "head" of the jellyfish would be, you've pretty much summed up what anemones are. They also have a long, fleshy stalk or base which acts as its torso, connecting the oral disc to the pedal disc. This stalk is soft to the touch, and can extend or contract depending.

The red circle towards the left is the anemone's foot.

 The tentacles of anemones and jellyfish are equipped with motion-sensing harpoons called nematocysts. The basic design of these microscopic deathsicles is that there are small chambers located all over each tentacle. Within these chambers is a harpoon or barb. The barb sits inside of the chamber attached to a very thin thread that stays coiled around it. On the outside of the chamber is a small hair filament that acts as a trigger. If the hair detects any contact, there is an immediate stimulus-response mechanism that fires the barb out of the chamber and impales whatever made contact with the hair. The biological beauty of this mechanism is that there is no processing done by the "brain" of the anemone. It's exactly what you'd call a "knee-jerk" reaction. It's a lightning fast impalement aimed at disabling its prey so that it can slowly move it towards its mouth and enjoy dinner.

Nematocyst up close (www.mesa.edu.au).

Anemones also only have one mouth, located in the middle of all its tentacles. Since an anemone is a single individual, it only has one mouth. Corals are generally a colony of individuals that live and grow together. This means that each individual of the colony, also called a polyp, has its own mouth that it uses to ingest microplankton. If you're staring longingly into a mass of tentacles (this is not a euphemism) and notice that it has more than one mouth (also not a euphemism), or that you can't even see a mouth, then chances are it's not an anemone.

Anemone showing off its oral disc and mouth, located in the center.

 If you look at the picture back up there showing the anemone's foot, you'll notice that the anemone doesn't appear to have an anus. Unfortunately for it, its mouth and anus are the same orifice. After the anemone has moved its prey into its mouth by way of its tentacles, it ingests the prey, digests it, then gracefully excretes the waste back through its mouth. Delightful creatures! I like to think of them as ocean stomachs, because all they really do is eat fish and get huge. They don't go on hundred mile migrations, they don't pounce on unsuspecting prey in heroic triumph, hell, sometimes they don't even kill their own prey. All they do is find a nice spot, plop down, and start waving their groovy tentacles hoping for a meal.

It's like a jack-in-the-box, except in reverse... and the crab dies at the end.

Psychedelic Shapes and Groovy Colors

Another important thing to note is that not all anemones look alike. There are anemones of all different colors, some of which are a combination of multiple colors, and their tentacles also vary between species. Their tentacles can be long, short, curly, or bulbous.

Rose bubble tip anemone (long tentacles that contract under intense lighting at the tips to form bulbs).

Ritteri or magnificent anemone (long, waving tentacles).

Carpet anemone (short, sticky tentacles).

Corkscrew or long tentacle anemone (long, curled tentacles).

The color of an anemone varies depending upon a few things. The color actually comes from the symbiotic algae that lives within the anemone. This algae is called zooxanthellae algae, and it is a photosynthetic organism that turns light into energy. Through photosynthesis, the algae creates food for the anemone, and in turn is given a place to live (within the anemone). Sometimes anemones will lose their color and turn translucent white. This is called bleaching and is generally due to the zooxanthellae algae leaving its host anemone. Unfortunately, this usually leads to the death of the anemone. Zooxanthellae are also responsible for the colors of all photosynthetic corals. Bleaching can happen to corals as well. Unfortunately, coral bleaching has become an increasing concern for biologists. Many reefs around the world have experienced intense bleaching events which have led to massive die-offs of the reefs.

Coral bleaching of a brain coral.

Coral or Anemone?

Now I'd like to take a minute and show you some corals and anemones and let you try and identify which ones are corals and which ones are our lovable ocean stomachs. Try and remember the important things to look for. I know it's difficult from pictures because sometimes you can't see the telltale signs of what makes it an anemone or not, but I'm not grading you so calm the hell down.

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Answers!

(a) Yes! This is known as a rock flower anemone. You can see its oral disc and mouth, along with its curled tentacles that border its oral disc. You can't make out the stalk because the picture was taken from a bird's-eye view.

(b) Nope! This is a coral known as a slipper or tongue coral. It's actually comprised of a calcium carbonate (what bones are made out of) skeleton surrounded with a fleshy skin. It has small tentacles, similar to the carpet anemone from earlier, however it lacks an easily identifiable mouth and it also doesn't have a round shaped oral disc.

(c) Nope! This is a coral known as galaxy or tooth coral. It has a massive amount of thin, long tentacles that it extends out to trap microplankton and to sting nearby corals. However, if you look closely you'll see that the tentacles are actually in small groups all over the face of the coral. This is because each little bundle of tentacles is actually a single polyp with its own mouth.

(d) Yes! I believe this is a white-spotted condy anemone. The stalk and tentacles are easily noticeable, and if you look closely you can make out a little bit of the oral disc. The oral disc also has the stereotypical round shape to it.

(e) Yes! This is a wild specimen of Heteractis magnifica, or ritteri anemone. This species is one of the largest known anemones. This particular one has a massive purplish stalk and beautiful lime green tentacles. The clownfish residing within it are known as skunk clownfish. They're generally pretty passive towards each other and other clownfish. It's not uncommon to have a mature pair and several juveniles sharing the same anemone.

(f) Nope! These are corals known as button corals. They have a central mouth, but there shapes are a little more oblong than we'd expect for an anemone. Also, they don't have any discernible tentacles. These corals also have calcium carbonate skeletons surrounded by a fleshy skin, just like the slipper coral.

(g) Negative. These are branching hammer corals. You can see that the heads (polyps) of the corals all attach to each other via their own long, calcium carbonate skeleton stalk. If one of these heads died, it would be possible for the rest of the polyps to survive. These corals are also generally easier to propagate as well. (Coral propagation can be done a number of ways. Propagating a branching coral such as this one is done by clipping off one of the coral branches at its base with a pair of bone cutters. The coral is then relocated and will eventually grow bigger and make new branches.)

The Sea Pancake

As I said earlier, I love anemones. They've always had a squishy, tender place in my heart. Unfortunately, anemones require a very healthy aquarium with very low nutrient levels. It's important to note here that "nutrients" in this sense refers to phosphates and nitrates, which are byproducts of fish waste (no one likes swimming around in their own... well, you know). And, if you remember, I wasn't exactly Mr. Diligent when it came to aquarium maintenance back in the day. Suffice it to say I'd killed my fair share of squishy sea stomachs. However, I recently acquired an awesome green carpet anemone (my favorite species) that my clownfish absolutely adore, and it's doing swimmingly! Without further ado, I present to you the sea pancake, the true anemone of the aquarium, Shakespeare.

Romeo and Juliet (tomato clownfish) with their carpet anemone, Shakespeare.

There's a lot more to be said about these amazing animals, but it's already a miracle if you made it this far in the post. In the future I'll try and do an entry more focused on anemones for aquariums rather than anemones in general if anyone would be interested in that. I just wanted y'all to have a little better understanding of what an anemone is and why they mesmerize me so much. There's a lot to be said about their symbiotic relationship with clownfish, as well as which anemones certain species of clownfish and damselfish prefer. But again, that's for another day. I hope you enjoyed learning about anemones! As always, if you have any questions, please don't hesitate to ask.