The Whistling Thorn Acacia (Acacia drepanolobium) is a species of acacia tree. They grow in many of the rainforests around the world and also in the Acacia Highlands of Kenya in Africa.

As protection against the many herbivorous forest creatures, the whistling thorn is armed wth two types of thorns. One type are pale color and grow in pairs on the tree. They are very sharp and stiletto-like and can grow up to thre ies long. The thorns grow from a hollow, bulbous swelling on the tree. Tiny holes can be seen in , which act like a flute in the wind, producing the whistling sound for which the acacia is named.

The whistling thorn is alw occupied by ants, some species of which live nowhere else. These ants live in a symbiotic relationship with the tree.

TREE/ANT RELATIONSHIP
The swollen, hoow thorns and thorn base provide a perfect shelter for the ants. Environmental condins seem to prent the ants from nesting effectively in the ground. Also, special glands on the tree, called "nectaries", produce a sugary excretion that is a perfect food for the ants, and see to be produced for that purpose alone. When the ants lay their eggs inside the thorn bas, they harvest several oval shaped polyps, called "Beltian bodies" that grow from the tips of the tree's leaves. These bits provide elent nourishment for the developing ants.

As for what is given in rturn to the tree, the benefits vary on the sies of ant living in the tree. There have never been more than one species living in the same tree because of a vient intolerance for eachother. Generally, though, there are only four different species which live with the tree.

Two of the spes are very aggressive, swarming and biting any intruder who so much as shakes a branch. This provides great protection for the whistling thorn, warding off any animal that may t to eat from it. Often, vines will attach themselves to the trees in an efort to so up the sunlight that is often scarce beneath the rainforest canopy. The ants will then sever the vine, removing it from the tree, practically ensuring the acacia's survival.

The other spees are far less aggssive, retting into the shelter of the tree at the first sign of trouble. However, if the disturbance sts, the ants will eventually attack the intruder.