Rachelle Marcon, our guide, led us to the koala “barn,” where the koalas were surprisingly active (likely due to the fact that it was nearing sundown, and most animals appear to be active around this time). However, despite their apparent playfulness, Rachelle informed us that koalas are not cuddly, and in fact are as good-tempered as an angry Gila monster. Koalas are the only animals that have adapted to eating eucalyptus, which secretes a deadly poison koalas must become immune to before partaking of their first solid meal. Yet, this does not mean every eucalyptus tree is an open buffet for the koala: the trees vary in toxicity according to the soil, climate, and general genetics of the tree, and thus can sometimes be too deadly for the most determined koalas. In fact, this is a reason one does not see colonies of koalas gallivanting around Southern California, despite our many groves of eucalyptus trees. Rachelle had asked an acquaintance in the horticulture department why this was so, and they explained that due to soil condition and climate the Southern California trees, although they were imported from Australia, are too poisonous for the koala. Another reason koalas are not seen in every Californian backyard are that in Australia koalas act as intrinsic members of their food webs. If koalas are removed, the natural economy will be affected. The natural economy is the amount of resources and minerals circulating through a system, and if these resources and minerals are depleted or bolstered, the human environment will suffer as a result.

On the subject (or at least mildly close to the subject) of trees, I learned something surprising: the San Diego Zoo, although renowned for its varied and massive collection of animals from every corner of the world, has an equally precious collection of plants. The Zoo also boasts an extensive collection of cycads, which are intriguing in that they are found on every continent but Antarctica and have distinctive male and female characteristics. As cycads seem to be somewhat closer in ancestry to humans than most plants due to the cycads’ difference in sex, cycads may hold some clues to the origin of life and humans own divergence from the primeval soup. Or maybe not, but it’s fun to speculate. Too bad for female cycads that they don’t get to choose their mates but are at the mercy of the wind spreading the pollen around.

Liz, Real World Team

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