Agonistic behaviour
The term has broader meaning than aggressive behaviour because it includes threats, displays, retreats, placation, and conciliation.
The term "agonistic behaviour" was first defined and used by J.P Scott and Emil Fredericson in 1951 in their paper "The Causes of Fighting in Mice and Rats" in Physiological Zoology.
Agonistic behaviour is a result of evolution,[5] and this can be studied in a number of species facing different environmental pressures.
Mantis shrimp, predatory crustaceans, are an example of an aggressive and territorial organism whose agonistic behaviour has been studied in an ecological and evolutionary context.
[6] These sea creatures are secretive, but highly alert and active predators who inhabit burrows and cavities along coral reefs, rocky coasts, and muddy shores of tropical and subtropical waters.
[6] Roy Caldwell and Hugh Dingle conducted research on mantis shrimp and other stomatopods, which focused on the evolution of agonistic behaviour and how it applies to the ecology of these organisms.
Stomatopods arose from leptostracan stock, as is indicated by fossil evidence, approximately 400 million years ago.
The spearing appendage is possessed by squillids, lysiosquillids, bathysquillids, and a couple gonodactylids; the last group contains both spearers and smashers.
[6] "Smashers" are able to use the raptorial appendage with such a force, particularly the gonodactylids, that they are able to smash the glass of double walled aquaria in the laboratory.
[6] Most species of stomatopods, regardless of the type of appendage, ordinarily deliver blows during agonistic encounters with the dactyl closed.
These crustaceans may deliver blows with the dactyl open but generally only in situations of extremely intense fighting displays, which are rare amongst most species.
Interestingly, this meral spread may be displayed dozens of times during an agonistic encounter and Caldwell et al. explain it is used as a method to inhibit actual physical violence.
These bright meral spots possessed by smashers are either yellow, blue, red or white and are outlined by a conspicuous black pigment.
Conversely, spearing Stomatopods or some smashing species that do not inhabit rock or coral cavities, have much duller meral spots.
Agonistic behaviour is influenced by the action of hormones such as vasopressin, which is a small peptide synthesized in the brain by magnocellular neurons.
[14] This antagonist has been known to decrease the tendency of offensive aggression via injections into the ventrolateral hypothalamus, therefore is able to act on multiple regions of the brain and exhibit the same effects of offsetting this agonistic behaviour.
Animals are better able to assess their next form of agonistic action by judging the opponent's size and if they are likely to win a fight if a physical altercation were to occur.
However, in a normal scenario if an animal is too aggressive it might face an unacceptably high cost such as severe injury or death.
[22] To avoid the heavy cost of fighting, animals have evolved sophisticated rituals, which they use to bluff their opponents into backing down or fleeing.
[23] Male western gorillas display a wide range of both vocal and gestural communications when threatened by an opponent.
[1] While ritual display can be used for an array of reasons or communicative purposes, threat distinctly is meant for hostility and is the last step before fighting or submission.
[24] In comparison to its body size, the frill can flare out to make the lizards head look several times bigger, and it displays bright orange and red scales.
The male ritualistic display includes repeated partial erections of the frill, head bobbing, tail lashing, and waving of forelimbs.
Fish such as Oreochromis mossambicus often exhibit aggressive displays, but rarely fight to the point of injury or bodily harm.
Agonistic fighting for black mambas involves a wrestling match in which opponents attempt to pin each other's head repeatedly to the ground.
[1] Submissive behaviours are part of the maintenance of a dominance hierarchy of cooperating individuals in a social group that have overlapping but not entirely coincident interests.
[27] Social interactions among bearded dragons (Pogona vitticeps) consist of a unique set of movements or visual signals.
