Thursday, 24 July 2008

The Acacia and the Ant

There are many symbiotic relationships in nature. Some relationships are visible: For example, cleaner fish remove parasites/dead skin from other fish and in doing so, provide a meal for themselves and clean the surface of the other fish. Other relationships are not so visible. One such invisible relationship occurs between the Bullhorn acacia and the ant. The Bullhorn acacia gets its name from the thorn-like structures on its branches, which resemble horns of a male bull. Unlike most acacias, the Bullhorn acacia lacks the bitter alkaloid which would normally protect the tree from attack by insects or grazing livestock. To compensate for the lack of this defence mechanism, the Bullhorn acacia produces protein-lipid nodules (Beltian bodies) which are used as a food source by ants living on the tree. These ants, which are harboured in the thorns of the Acacia, use the protein-lipid nodules to produce and secrete pheromones which are picked up as a deterrent by other insects and grazing animals. Furthermore, the ants are capable of a nasty sting which acts as an additional deterrent.

(2) Image: Dan L. Perlman ( /Ant,Bullhorn_Acacia,thorn,Pseudomyrmex,EL_DP162.jpg)

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