ok, lets rock!
chemical warefare is made up of a few different stages or employed in different combinations. typicly iit is designed to deter or damage a potential threat to the point of retreat so they may expand and dominate an area! keeping in mind most of the animals in questionwhich are capable of this prefer to be or are sessile animals.
now im not sure how other corals know there is competion in the area, (tanks in our case) im assuming its a chemical signal or terpenes that each animal produces and is released. id have to ask evolution for abit of clarity on this one! what i do know is that excites dormant areas within the animal, setting off a chain reaction to grow instuments of war that can be completed in some species within a few days! although some developments can be up to a few weeks!
another factor to take into account is what species are engaging in battle. cause even when being attached on muilt fronts, some will still lock on to one attacker only to become damaged at the point of contact from the other.
in saying that Barnes & Hughes did an experiment in 99 on just this, only to find after the retreat the defeated coral invested its energy into sweeper tenticals which it sent out and thus created a perminant barrier between the two.
ok so now on to the tools of war....
we have
sweeper tentiacles, these are kinda self explanitory, these are purpose designed poylps that are thinner and much longer & are filled with
nematocysts.
they grow these to protect the outer permeter zones and are packed full of stinging cells to inflict maxium damage with minimun contact or proximity!
a corals aggressive effeciency is measured with the amount of nematocysts per polyp head.
^ BORDER DEFENSE. An anemone polyp (arrow) leans over to attack a small scout from the patch of clones next door. An empty zone (central swath in inset) separates patches of clones.
then we have mesenterial filaments, these are from the coral's digestive organs, & can be used as another battle aid! during battle, one of them, the aggressor, will extrude mesenterial filaments through the mouth cavity or the body wall onto the surface of the other, literally digesting it's tissue. the result is a zone of naked skeleton that can then be overgrown. this zone can be overgrown by the attacking coral itself or it can be colonized by encrusting organisms, thereby creating a "buffer zone" between the two species.
allelopathy is another process of chemical warfare, or more locally the word is toxic terpenes expolsion. this a basicly a chemical control agent thats released indescrimanately by the coral to "stunt the growth" of any would-be invader! very effective at keeping the growing zone clear for the future!
and finally we have acrorhagi phaze. these are mainly associated with anem's. they are grown or inflated in the zone below the tenticals themselves. basicly they are sacs that are teaming with extra stinging cells that when called apon can unload hell!. also when these sacs make contact with another anemone, they leave behind a layer of tissue that results in localized tissue death of the intruder. thus once again leaving the door open for a buffer zone between the two parties.
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V-series Productions 
and do you think maybe you could fill us in on the chemical warfare factor? 