Coral Aggression & Thoughts on Coral Placement

Coral Aggression & Thoughts on Coral Placement


Hello everyone, and welcome back to Tidal
Gardens. I, like many people who get into the reef
keeping hobby, did so because of how peaceful and serene coral reefs are. The intense colors… the beautiful fish…
tranquility… what’s not to love about coral reefs right? Well… this is a factory of lies! Underneath that veneer of peace and tranquility
is a world of aggression and endless warfare between the corals on the reef. Fish? They are total jerks. Peace and quiet? Hell no. If I’m scuba diving, I can tell you blindfolded
if I am in a coral reef or not because it is LOUD. It sounds like a bowl of rice crispies IN
YOUR SKULL. Sorry about that, got a little carried away
there. This video though is all about coral aggression. It plays a big role in how we place corals
and build up our reef tank. Let’s get into it. Everything on a coral reef is trying to battle
for more real estate and the organisms on the reef developed specialized methods to
wipe out their neighbors whether that be other corals, algae, or inverts. You might be thinking… but wait, not EVERYTHING
is trying to kill each other… what about symbiotic relationships? That is true to an extent. Years ago I did a video all about symbiotic
relationships showcasing cooperation between very unlikely partners. One might get the idea that these sorts of
things are common, but a coral reef is not some beautiful utopia. It is a landscape of intense competition for
resources and these symbiotic relationships only exist to further the competitive strategy
of the partners. For example, let’s look at the most iconic
symbiotic relationship in the hobby, that between a clownfish and an anemone. In a vacuum, both the anemone and the clownfish
would be better off alone. The clownfish is getting constantly stung
by the anemone, it has just developed some degree of resistance. The anemone is being constantly battered by
the clownfish and often getting its tips bitten off. But… this relationship makes sense because
the anemone provides protection to the clownfish from potential predators and in return the
clownfish provides protection to the anemone from fish such as butterflies that might make
a meal out of it. So, there is a net positive from this relationship. This shows that even in cases of cooperation
it only makes sense in the context of competitive advantage. That was a little bit of a tangent but it
illustrates the point that every coral or invert we place in our tank has some mechanism
of competition that they are more than willing to unleash on its neighbors. As responsible reef keepers we should take
that into account when deciding on both acquisition and placement. And THAT is what this video is really about. So let’s start talking a bit about what
those mechanisms are. First of all, corals possess nematocysts,
or stinging cells. Nematocysts are used for both prey capture
as well as defense. These venomous cells are not unique to corals
as they are found in anemones and jellyfish as well. Some organisms developed adaptations to acquire
nematocysts when they cannot produce the cells themselves. Zoanthid eating nudibranchs for example eat
the polyps and store the nematocysts in these sacks on their backs. That is why often times the nudibranchs take
on the coloration of the zoanthids they have been feasting on. How they work is each nematocyst is a pressurized
capsule that features a coiled thread with harpoon-like spines. These cells are under a lot of pressure so
when they are triggered, this coil fires out and stabs into the target and injects its
venom. The power of the sting depends on the structure
of the nematocyst as well as the toxicity of the proteins it fires into the target. Some stings are very mild while others are
very intense. For example, the nematocysts from a Pseudocorynactis
mushroom are very sticky and it is able to grab onto and hold large fish. In fact, those can easily stick onto your
hand and get lifted right out of the water. Most of the time our skin is thick enough
that coral stings aren’t that noticeable, but sometimes people are more sensitive to
a particular coral. For example, some people are very sensitive
to frogspawn and immediately break out after handling a colony. In extreme cases, people can get very ill. Some people are allergic to the venom from
carpet anemones and there have been reported deaths from allergic reactions. How this relates to coral placement is that
some corals are able to create hyper weaponized forms of tentacles called sweeper tentacles. A sweeper tentacle is a greatly elongated
tentacle with a concentrated mass of nematocysts at the tip. These sweeper tentacles are most commonly
found in large polyp stony corals such as euphyllia, certain brain corals, galaxea,
the list goes on but they are also found in some small polyp stony corals such as Pavona. If you have a coral that is capable of sending
out sweeper tentacles, it is important to give it a lot of room in your tank because
they can cause a lot of damage to neighboring corals. This is often easier said than done. Some corals can extend sweeper tentacles up
to a foot away. Next up are two short range weapons, mucus
coat and mesenteric filaments. Mesenterial Filaments are the inside guts
of a coral that some species can expel onto nearby adversaries. Mesenterial filaments contain nematocysts
as well as digestive enzymes and can do significant harm by coating the target for hours. Eventually the coral retracts these filaments
leaving behind a clearer substrate to grow upon. It is thought that mesenterial filaments used
in this way are used both for aggressive expansion as well as nutrition for the coral when they
are withdrawn back into the coral. Often times this behavior happens at night
so it is entirely possible to have two corals situated close to one another be fine but
when you wake up the next day one of them is completely dead… a victim of a mesenterial
filament attack. Almost every type of coral is capable of extending
mesenterial filaments but some are more aggressive than others in this regard. I see them commonly in favia, favites, pectinia,
hydnophora, and many types of chalice corals. This next or is a bit of speculation on my
part but it is an observation of mine for years. Mucus coats on various corals can cause serious
damage to other corals even after brief contact. The mechanism for this hostility isn’t well
documented but it is pretty clear that whatever it is it happens quickly. It is not uncommon for a coral to fall off
of the rock scape face down on another and both corals immediately start showing signs
of damage. If left that way for a few hours both corals
could die outright. There are some studies that indicate the mucus
coats of corals provide all kinds of benefits such as UV protection, microscopic prey capture,
and protection from detritus settling on the coral by periodically shedding the coat away. On the flip side however there are studies
showing this mucus coat is also a dense breeding ground for bacteria and viruses. Like I said I am not sure what makes the mucus
coat of a coral tick, but in practical terms, it is important to place corals in such a
way that you minimize the likelihood of contact. Anticipate future growth and make sure to
place corals securely so they don’t lean into or worse yet fall on top of each other. The last coral aggression adaptation I will
discuss in this video is chemical warfare. Some corals don’t necessarily pack a mean
sting or barf up their guts and dissolve their neighbor. Corals such as these toadstool leathers can
secrete toxic compounds into the water that slowly poisons everything around it. How this manifests is that other corals around
it especially stony corals simply stop growing. The secreted toxins are metabolites which
may include: Terpenoids which are a super diverse group
of natural compounds that are often associated with protective oils. For example some plants have an oily coat
that makes them toxic to insects and other herbivores or termites have terpenoid-based
oils that make them unappetizing to potential predators. These terpenoids are also precursors of polyhydroxylated
steroids that have been detected as well from certain leather corals. There are also Acetates and Polyamine compounds
that are all potentially bio active. In fact, several of these compounds are being
investigated for therapeutic uses because some are inhibitors of chemical pathways which
are very interesting in drug development circles. To sum that all up, corals are capable of
excreting a cocktail of bio active compounds in an effort to wipe out neighboring organisms. The corals associated most with these chemical
toxins are leather corals like sarcophyton, lobophytum, lemnalia, etc. So what can we as home hobbyists do about
corals that engage in chemical warfare? Some aquarists chose to avoid these corals
altogether especially those that are trying to create an SPS dominated tank. A tank full of acropora can be challenging
enough without adding large corals that can stunt their growth into the mix. Having said that, there are plenty of people
that keep stony corals with leathers. It may not be ideal but it can be done. There have been plenty of times that I have
kept leather corals and acropora in the same tank. If you decide to try something like this in
your reef aquarium, there are three techniques that can help. The first technique is to perform more water
changes. By changing out water, this will serve to
dilute the concentration of toxins that build up in the tank. Second method is running activated carbon. Activated carbon works by permanently binding
up compounds through adsorption which happens at the surface of the media. As the media fills up it will have to be replaced,
but activated carbon is inexpensive and readily available. The third and by far the least commonly used
method is to run ozone in the tank. Ozone is O3 a highly reactive molecule that
has powerful oxidizing properties. In an aquarium application it is generated
by an ozone machine, usually by passing oxygen through an electrical field splitting the
O2 molecule and allowing the oxygen atoms to re form as ozone. In the aquarium, ozone has a variety of effects
such as clearing up the water as the ozone breaks down tannins that give our aquariums
a yellow cast. It also virtually eliminates any tank odors. The effect we are interested in for this discussion
is how affects the toxins that corals can emit. The extreme reactivity of ozone causes these
toxins to break down upon contact to less harmful compounds with little to no bioactivity. There are severe downsides to ozone, such
as safety risks if there is a malfunction. If you are interested in trying ozone, as
I am, be aware of the risks and have security measures in place to detect possible leakage
of ozone into the air. All right. That pretty much does it for our discussion
on coral aggression. To sum things up, corals developed all kinds
of adaptations to gain a competitive advantage in the battle for real estate on the reef. In our home aquariums we have to be conscious
of these in order to find the best location for them long term. I hope you enjoyed the video and please leave
a like on the way out. Best of luck in your own tank and I hope to
see you all next time. Happy reefing.

50 thoughts on “Coral Aggression & Thoughts on Coral Placement

  1. Coral aggression is the #1 reason why I lose corals these days. Do any of you have problems with corals killing each other?

  2. Peace and tranquility…… It all a lie😹😹😋😋lmao.

  3. Currently I am walking the path of research for my first reef. I was just pondering about this very subject over the weekend. Fantastic timing! Thank you so much for all of your videos. Your videos always have amazing visuals to enhance to illustrate the topic. Your videos are always very clean cut, informative, and presented in a very professional way. They have been extremely helpful in my quest for knowledge all things reef related. Thank you for every single video. Noobs like me really need them. Cheers.

  4. Another great video very articulate and informative. Thank you.

  5. Than, sir if I have a leather coral with my sps dominated reef am I taking a chance on less growth of my sps? Or even risking damage to my reef? I don't get the growth that I want and I cant fiqure out why could it be because I have a leather coral?

  6. I think Voltaire said in response to Rousseau's rhapsodizing of Nature and its peacefulness, "In Nature, spiders eat flies."

    I never understood the concern for ozone, as it rapidly dissipates and is very easily detected by our sense of smell. If there are even slight leaks, they will be detected. Ozone is opposite carbon monoxide in the sense that the latter is undetectable before it kills you.

  7. Great video. This is a very overlooked topic that effects every reefer.

  8. The toadstool and sps is so true

  9. Between the mellow narration and the beautiful shots I always feel like I'm coming away from an expensive therapy session after each video 😀

  10. Very informative as usual. One thing which is hard to understand however as I am a newbie. All these display tanks you see are always dense with corals. How is this possible with all the warfare going on?

  11. Great Video!

  12. Fantastic video.

  13. great video and topic….

  14. How often would you change your activated carbon?

  15. Next time you are diving look at the base of some hard corals and soft corals like gorgonians and sea fans. Often what you will see is a birds nest. They are either parasitic or commensal or symbiotic.

  16. You do not mention coral placements. Maybe on next video?

  17. My War Coral in my 35g Cube is about 7 inches radius. I have seen it extend its tentacles about inches long. Its truly a hairy mess. Killed my Torch, some neighboring Zoas, Devils Hand, my Candylactus Anemone (it moved to defend itself) it put a spot on my 8 year old Tomato Clown. The only Coral that defend itself (fought back) was the War between it and the Galaxea (which is half the size that the War Coral)
    I don't recommend putting a War Coral or a Galaxea Coral in a rock structure. Sand bed islands are best placement for both. Otherwise as they grow, good bye to anything near by. I have a love/hate relationship with them.
    Awesome video as always Than. BTW that War Coral was purchased from you 2 years ago. Now it's about 7 inches big.

  18. Superb video! Added to my collection of reef aquarium essencials!!!

  19. Excellent video as always! I knew some of the warfare, but this was very thorough and informative. I learned a lot. Thanks Than for your insights and amazing video. Can’t get enough of your work!

  20. Très intéressant, merci !!! 👍👍👍

  21. King of the underworld for videos !!!!! Thanks Than

  22. Great video, I enjoyed watching it.

  23. Ok so what are the least aggressive corals?

  24. Visually this is amazing. The narration was amazing. Def one of the best reef videos on YouTube!

  25. Coral reefs are basically 24/7 episodes of Cops. Me. I am the cop.

  26. Why not use an Oxydator as a safer, cheaper alternative to Ozone? Works great for me and many others… I run a W model with 12% peroxide on my 350 gallon.

    https://www.oxydator.de/soechting-oxydatoren/

    https://www.reef2reef.com/threads/anyone-using-dr-sochtings-oxydator.194240/

  27. Very informative and helpful summary of tank warfare.

    As I start to introduce SPS into my tank, I will have to consider fluidising carbon.

    Currently I fluidise Seachem Cuprisorb 24/7

  28. Great video as always. Thanks for the amazing content.

  29. This must have taken days to put together. Incredibly valuable info. Thanks!

  30. I love these scientific level videos you put out!

  31. That rice crispy sound can be heard along every coastline. I believe it is mostly caused by wave action and the ability of sound to travel longer distances in dense media such as water.. The only place where it is relatively silent is open ocean.

  32. I think I need to either move my frog in a blender SPS or my mushroom. I am running carbon. I really hate the Scape on that side of my tank so I'm happy to move things around.

  33. Knows what he’s taking about and very helpful keep it up man <3

  34. I always love your more scientific approach to the videos you produce but in that mention I must correct you. Clownfish are not stung multiple times while they are interacting with their host. The hypotheses is that they develope a mucus layer that prevents the anemone from stinging them. Here is a link that describes some resent research. https://www.sciencedaily.com/releases/2019/06/190619142547.htm
    The mechanism that protects clownfish is still being researched and has been for a long time!

  35. Once again a fantastic production great work Than. 👍🏻

  36. I don't undrestand why one would use ozone in his/her aquarium. It is a free radical, meaning that it has an unpaired electron, and reacts freely with organic tissues. It can cause many forms of damage to cells and tissues, such as disabling enzymes, and mutating DNA. I would assume that it is also toxic to corals?

  37. 3:49 what is the name of that coral please help

  38. anyone know the name of the chalice coral at 8:02?

  39. Fantastic topic Than.

  40. 10/10 Video Than! Extremely informative

  41. Well spoken as usual and chemical warfare probably kills a majority of new hobbyist tanks without then realizing it

  42. you have taught me everything about corals, now I own a 20gal reef tank. Keep up great vids.

  43. great video than. The audio was really good.

  44. Fine coral

  45. hydnophora is a little monster. pavona can be aggressive.
    i have the two side by side, by constantly attacking each other, they create sculptures.
    my sexy shrimp love hanging around in there.

  46. Does waving hand Xenia have anything bad? I pulled a ton out today and one spayed my face.

  47. Brand new to the channel and new to the hobby. I live 15 minutes from you and am so impressed by your work! Looking forward to educating myself here!

  48. Have you heard about oxydators as an alternative to ozone?

  49. Another great video. Thank you for the eye candy and information.

  50. So am I correct in saying don't let sps touch don't let lps touch and don't put strong stingers like hammers next to anything?

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