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 12 green thorn interior DHJanzen100094.jpg high resolution
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| A green, newly produced (and still living) thorn that has been broken open at its base to show the soft white pulp filling the interior and the ant hole burrowed/chewed through it, from the single entrance hole cut near the tip of the thorn (see next photograph DHJanzen100095.jpg). This pulp is excavated out by the acacia-ants in rendering the thorn suitable as yet one more living space among the many on the tree (see image DHJanzen100106.jpg below). The entire ant colony lives in these thorns, and does not (any longer, evolutionarily) live in hollow twigs or on the ground (or on other species of plants). One acacia-ant colony may, however, occupy several individual ant-acacias (even two of two species). These thorns, in contrast to those produced on non-ant-acacias, are not produced in larger size and numbers in response to browsing of the acacia, something that presumably has not happened for many tens of thousands of generations in the ant-acacia lineages. They are produced in the same size and numbers by the ant-acacia whether growing in nature with an ant colony or in a greenhouse (or in nature) without one. | ||
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