Summary

In this module, we have attempted to introduce you to the extraordinarily complex world of invertebrates. Invertebrates are found in every context, as both free-living organisms and as ecto- and endoparasites. Some groups, such as the nematodes, are barely known, mainly because of the difficulties of identifying them to species level, their presence at multiple trophic levels and because many are endoparasites. Humans, for example, are host to at least 35 species of nematode. Despite the lack of knowledge about them, they occur in startling numbers: they may account for 80% of all individual animals on Earth.

Ants are also abundant in tropical forests, and there are many examples of myrmecophytes in the Tropics. Ants fulfill a number of different ecological functions, and occur in large numbers. Some defend their host plants against herbivores, whereas may defoliate plants. They have been the subject of numerous detailed studies, but there are still many questions about their basic ecology.

For most tropical forest ecologists, the most important group of invertebrates are the insects. This is because of the enormous role they play in pollination, but also because of the other ecosystem processes in which they play a role (such as decomposition, herbivory and seed predation). As with other invertebrates, only a small percentage of the insects have been described, although some groups, such as the butterflies, are better known than others. Some regions are also better known than others, such as the tropical forests of Australia and southern Africa.

A particular feature of tropical insects is the extent to which some have specialized on particular plant species. This has significant implications if the host plants are lost and, for example, many butterfly species have disappeared from Singapore, apparently because their host plants have either gone or become too rare to support viable populations of the insects.

Some final words about this course: