Passage IV

NATURAL SCIENCE: This passage is adapted from Sarapiqui Chronicle by naturalist Allen M. Young (©1991 by the Smithsonian Institution).

Converting dying or dead tissues into nutrients is what binds the creatures of the tropical rain forest into a functioning unit. Thus the giant trees, what I have come to love and admire about Sarapiqui [rain forest] when I stop at a ridge above the forest canopy, are supported precariously upon a thin, fragile tissue of microbes and organic matter, matter that is turned over, transformed by millipedes, sowbugs, ants, and millions of other tiny creatures. Without these hidden, largely unseen assemblages of life, the giants would be no more. But this exquisite association between big trees and the Earth’s tiniest creatures has structured and guided the development of Central America’s and South America’s rain forests for millions of years. With the fixation of energy from the sun through photosynthesis to make living plant tissues, and the continual absence of a cold temperature winter season, the tropical rain forest pulses with energy, most of it tied up in the bodies of its living creatures, corpuscles of nutrients feeding into one another.

What a fascinating, elegant circle of life Morpho [butterflies] symbolizes in this regard. Plants die in the rain forest, including the woody vines Morpho caterpillars feed upon and are evolutionarily specialized to exploit, and saprophytic fungi and bacteria attack the dead plant material. In the process of breaking down dead plant material to feed themselves, the fungi metabolize substances that become attractive to Morpho. The eventual breakdown of the dead plant material provides the rain forest with the fertilizer it needs in order to survive, including the woody vines and other legumes fed upon by Morpho caterpillars. Morpho also gets nutrients from the decay organisms as well.

Morpho symbolize a great deal about the workings of a tropical rain forest. When mushrooms break down the dying and dead tissues of a log or tree trunk, these saprophytic organisms are releasing valuable nutrients into the rain forest, to be fed upon by living plants. So too when the very large grub of a Megasoma or Dynastes scarab beetle, what the Costa Ricans call the cornizuelo, ingests the rotting wood of a tree stump, it is also unlocking essential nutrients to nurture the rain forest. And when birds peck holes in the trunks of trees, exposing sap that soon becomes encrusted with fermenting mold. Such mold, like that of rotting fruit in the forest’s canopy or on its floor, converts nature’s most ubiquitous fuel molecule, sugar, into the structural building blocks of life, proteins and other substances. Morpho’s own existence, together with that of legions of other insects and other arthropods that disperse bacteria and spores, ensures this rain forest will nourish Mucuna and other legumes that feed this butterfly’s curious red and yellow caterpillars.

But this intimate biological partnership between microbes and big trees in the tropical rain forest is being broken apart by deforestation. And as I write, this situation has tragic implications for Morpho, creatures whose own lives are also a cognitive piece of the living tapestry of Sarapiqui’s forests. It takes about 150 Mucuna leaves to make one mature caterpillar of Morpho peleides, or a wet weight of about 20 grams of plant flesh to produce one butterfly. Typically a clump of Mucuna or Machaerium occupies little more than a few square meters of habitat floor space, an area not even the girth of an average canopy tree of the tropical rain forest. For one Morpho or several individuals growing up in the same vine patch, not much forest space is required. But the food resources of morphoes, their caterpillar food plants and the juices of decay for the adults, are spread out through the rain forest. Thus the existence of a single Morpho is spread out through the forest as well. Morpho cannot survive in just one small place: yet it takes about ten acres of tropical pasture to fatten a Brahma steer for slaughter.

How many more mornings when the rain forest bathes in tropical sunshine will there be for me, anyone, to witness the incredible beauty of Morpho dancing above the Tirimbina creek? And how much opportunity to see this will there be for much of the floodplain of Sarapiqui? Outside of the La Selva Biological Reserve and the adjoining Braulio Carillo National Park, much of what has been home for Morpho is rapidly becoming beef cattle pastures.