The New Neotropical Companion

Seeds often contain toxins, and thus, though fruit pulp
is digested, seeds are not. Seed toxicity enhances the
probability of dispersal, as the seeds pass through the
digestive system of the fish.
At the close of the flood cycle, when the waters
drop, adult Tambaquis migrate from nutrient- poor
blackwaters to nutrient- rich whitewaters to spawn.
Juvenile Tambaquis feed on zooplankton, not fruit,
in the whitewaters along várzea floodplains and
lakes, where the rich soil provides the water with an
abundance of sediment (chapter 6).

Other Fruit- consuming Fish

Even the notorious (and carnivorous) piranhas are

known to consume seeds, removing the husk and

masticating the soft seeds within. Piranhas (plate 10-

25) belong to the characin family (Characidae), and

many characins are seed predators, possibly the most

important seed predators in the flooded forests.

Catfish (plate 10- 26) are not as destructive to

seeds as characin species because they gulp the fruit

whole rather than macerate it. In this sense catfish

are the piscine equivalent of birds such as toucans,

digesting the fruit pulp while the seed passes out of

the alimentary canal unharmed.

Pollination: Animals as Surrogate

Sex Organs

Brightly colored flowers are ubiquitous throughout

most terrestrial ecosystems on Earth, and are certainly

well represented in the Neotropics. Flowers invite

pollinators as surely as the Golden Arches invite

hamburger seekers. Pollination of plants by various

animals, a clear example of coevolution, is widespread.

Many flowering plants, particularly in the tropics, are

dependent upon insects, birds, or bats to facilitate

fertilization. Animals use flowers as a food source,

ingesting nectar and, in some cases, pollen. As they move

Plate 10- 25. Piranhas are among the many kinds of
Neotropical fish that on occasion act as seed dispersers. Red
Piranhas (Pygocentrus nattereri) are shown. Photo by John
Kricher.

Plate 10- 26. Species such as these Amazonian catfish are often important seed dispersers. Photo by John Kricher.

170 chapter 10 tropical intimacy: mutualism and coevolution