Africa.
Here on the savannahs of Kenya,
termites are the basis of a whole community of life,
and their impact reaches right to the very top,
to the tallest land animals.
Acacia trees take advantage of nitrogen-rich termite mounds.
The trees often grow next to a termite mound
and their roots tap directly into this resource.
The difference this makes is huge.
Acacia trees near a termite mound
grow 60% more new shoots and are twice
as likely to bear fruit than those far away.
But all this extra nitrogen makes the tree
very attractive to herbivores.
So acacias produce these sharp thorns to defend themselves.
But these antelope have a tiny head
that fits between the thorns.
And the elephants don’t seem too bothered by the spikes either.
One kind of acacia employs another line of defence,
and this starts off a cascade of relationships.
The whistling acacia modifies some of its thorns
to make these round galls,
which house an ant army.
The ant queen drills a hole in the gall
and lays her eggs inside.
The sound of the breeze blowing across these holes
is what gives the whistling acacia its name.
Inside the gall,
the larvae develop and the worker ants shelter.
A single branch might have a dozen or more galls.
When herbivores try to feed on a tree, the ants attack,
biting and then wiping poison into the wound.
Elephants hate these ants,
which are thought to attack the inside of their sensitive trunks.
So elephants avoid the whistling acacias.
But giraffes can exploit this food source.
They can close their slit-like nostrils
and use their long, tough tongues to wipe away
the ants before being bitten.
But even for giraffes,
especially the youngsters,
it eventually gets too much.
