Anemones were fighting before the Great War!

Species: Anthopleura elegantissima

Geographic Range: Pacific Coast of North America

Habitat: Rocky shores along the coast

Yes, that guy! In general, these anemones are colonial animals and were probably one of the first species to ever form a battlefront (more on that in a minute). They have an extremely long evolutionary history and for such simple creatures they live rather complicated and harsh lives in the rocky intertidal.  

These guys can reproduce asexually and form colonies of genetically identical individuals--or clones. The most impressive thing about this is that the anemones have the ability to distinguish between individuals that are genetically identical to them and those who aren't. They live in environments where there is a constant struggle for space so they are extremely territorial and genetically identical groups isolate themselves from the others (sounds a little "ethnocentric" doesn't it, ha). It is pretty much the idea of western expansion post Civil War and everyone competing for land that they believe is theirs. The only difference is we look like this when we fight wars:    

Anemones have their own ammunition and it's called acrorhagi. All anemones have stingers or nematocysts embedded in their tentacles that they fire upon mechanical or chemical stimulation. This stinging power is not strong enough to hurt us or a lot of other vertebrates, but when it comes to smaller guys they are pretty much done for. Acrorhagi are a special form of these stinging cells, but they are used to fight battles and they fight battles the exact same way humans did during the Great War when they formed stalemates. Here's how the inverts do it:

1. Set up a group of warriors along a boundary. These are the ones the colony is willing to sacrifice. 

  

2. Put the more important individuals behind these guys and form a social organization. In the case of these anemones, the more fit reproductive individuals are in the back so that genes can be passed on if all warriors are lost.

3. Send forward a scout (very slowly because these guys are slow moving) to scope things out. When this individual is attacked and returns to his front he is attacked by his own colony. The scout serves as a means for the colony to make sure that the threat they perceive is really there.

4. Engage in war! When the warriors encounter the other colony they use their acrorhagi (the big white tentacles underneath) to defend themselves by extending these organs and placing them on the other individual. When they do this the epidermis peels off and continues to release "fire" or stinging cells onto the other individual. This is extremely detrimental to the attacked individual and results in tissue necrosis.

Battle Video: