The rainforest is a place of extravagance: beautiful, brightly colored and sometimes downright bizarre plants and animals of every conceivable form await those intrepid enough to travel to the tropics to seek them out. Here, the diversity of form is matched by a diversity in the way in which organisms survive, what biologists call their ecological ‘niche’. Many rainforest mammals, for example, live much the same way their temperate counterparts do—hunting for other animals in the dark of night, browsing for young leaves and shoots, or digging for roots and tubers. But in the tropics, where temperatures are higher and more constant, and where plants are orders of magnitude more diverse and abundant than in temperate regions, resources are available to support lifestyles that are impossible elsewhere.
In the photo above, a tiny pygmy marmoset, the world’s smallest monkey, clings nervously to the bark of a Parkia tree, taking turns between nervous vigilance and intense interest in a goopy sap that oozes from pockmarks scattered over the entire surface of the tree’s massive trunk. This sap, rich in sugars and nutrients, forms the basis of this tiny primate’s diet. What the marmoset does not receive from the Parkia’s sap it supplements with insects and whatever other small animals it can capture—weighing about a fifth of a pound, suitably-sized prey are few and far between.
Pygmy marmosets are not the only rainforest animals that feed on the nutrient rich gum produced by trees. Insects—butterflies, wasps, lantern bugs, cockroaches, ants, and beetles, to name a few—are attracted to the holes excavated by marmosets in the bark of trees such as the Parkia. For an insect, a visit to a marmoset’s gum hole is a risky affair, since sap flowing from a hole in the tree’s bark suggests a hungry marmoset is nearby. The nutrient- and energy-rich sap is clearly worth the risk, a fact attested to by the number and variety of insects visible at the holes.
The rainforest is also a place of extremes. In the western Amazon, pygmy marmosets feed from the same tree gum as the white witch (Thysania agrippina), a moth with the largest wingspan of any insect on earth. Measuring in at up to 13 inches across, the moth is as much as two times larger than the tiny marmoset!
Below, a lantern bug (Phrictus quinqueparitus) feeds on the sap of a Simarouba amara tree in the Costa Rican rainforest. The bug must often share its tree with the bizarre peanut-headed Fulgora laternaria, another lantern bug.