Can you see the battle?
The acacia tree has an umbrella shaped crown with many tiny leaflets. These leaflets are precious reservoirs of moisture in the arid areas of East Africa.
The giraffe has acute needs for moisture and food. It also has a long neck allowing it unique access to the acacia crown.
But the acacia branches are lined with sharp spines to thwart browsers like a giraffe.
But the giraffe has a long tongue, capable of stripping the leaflets and twigs from between the thorns. It also has a tough mouth and really gooey saliva that coats the munched mess and helps it swallow (Imagine how horrible a sore throat would be for a giraffe!).
But the acacia tree has two lines of chemical defense when it senses an attack. Internally, it releases a tannin that turns the tiny leaves bitter, and if ingested in quantity, poisonous. Externally, the acacia releases a gas into the air. Other acacias, located downwind, get a whiff and release their own tannins, becoming inedible for a period of about two weeks.
But the giraffe has long legs. He tastes the tannins, moves on, upwind, to find an unsuspecting tree. He stretches and takes a nibble.
But biting ants swarm the mouth and lips of the giraffe. It appears that some acacias have hollow swollen spines, a perfect home for biting ants. The tree provides the ants with sweet nectar and shelter, and ants serve the tree as bodyguards.
The giraffe shakes off the insects and moves on.
And so the battle rages between the muncher and the munched.