Herbivory 

Herbivory is the act of predation on the plant. When the animal munches on the plants leaves, it is taking away parts of the plants apparatus for energy production.  Herbivores can be browsers or grazers. Grazers feed on grass. Browsers nibble on a range of plant foods. Browsers in the tropical rainforest include several species of possums that munch their way through the leaves of the canopy (right, upper photo). Grazers include pademelons (right, lower photo), although to feed on grass these animals often have to move to the edge of the forest to feed. Grazers are not as obvious or dominant force in the tropical rainforest as they are in the adjacent savanna woodlands where there are large areas of grasslands to graze on.

A red legged pademelon grazing on the edge of the forest

A possum feeding on the leaves in the canopy of the forest

Herbivores can be any sort of animal, from the biggest land mammals on earth (elephants), to some of the smallest insects (termites). Herbivory by larger animals is not as important or obvious in the rainforest as it is in the adjacent savanna woodlands. In the tropical rainforest it is the constant attack on plants by the smaller insects that really constitute the major battles of herbivory.

Herbivory

Plants have evolved many of their own defence strategies. We usually divide these into two different types of defences; physical and chemical. Physical defences are quite often external and usually obvious to human eyes. The simple toughness of leaves and their waxy coating can act as an effective barrier against chewing mouthparts, especially of smaller insects or early larval stages. Spikes, spines and stinging hairs may also act as a defence. An example of this type of plant found in the tropical rainforest is the ‘Stinging bush’.

The stinging bush

Flowers and Pollination 

Flowers are often not as obvious in the rainforest as people expect. Many of the flowers are high up in the canopy, are very small, or not all that colourful. However, there is in fact a wide range of colours and forms. This diversity of forms reflects the wide range of different pollinators in the forests, for the form of a flower reflects its pollination strategy.  Different plants may try to attract different specific pollinators or vectors. For example, those flowers that have evolved to attract birds will tend to have bright colours such as red, pinks and yellows, such as the Evodia (pictured), reflecting the strong sense of sight in birds. Those attracting mammals will tend to be duller in colour but with a stronger odour, such as Bumpy Satin-ashes, reflecting the mammal's nocturnal habits and sense of smell.

A scaley breasted lorikeet feeding on flowers

Seed and fruit dispersal by animals 

Ultimately fleshy fruits have evolved to attract animals to ingest them and thus act as dispersal agents for the seed. And in the end, the seed is not only dispersed away from the parent tree, but it is also provided, by way of the animal feces, a microsite of moisture and extra nutrients. This latter advantage may be very important in the competitive rainforest, especially in those that grow on relatively nutrient poor soils. Animal dispersed fruits advertise, just as flowers do, with various cues such as colours and smells.  Animals that feed mainly on such fruit are known as 'frugivores'. While there are, for example, no such specialized fruit eating birds in the whole of the northern temperate region of the Earth, the rain forests of Asia, the Americas and Australasia are rich in many avian frugivore species. Birds are the best known and most effective. Australasian rainforests may are often noted for their specialized fruit eating birds. Here in the rainforests of Australia's wet tropics bioregion, over 40 species of birds have been recording regularly including fruit in their diet. There are 7 species of frugivorous pigeons, bowerbirds and catbirds, the birds-of-paradise, the old world Orioles, the metallic starling, parrots, and several of the honeyeaters. It is the biggest bird of the rainforest, the Cassowary, that is probably the single most important animal seed disperser of the local rainforest. So far, over 200 rainforest plants have been recorded to be eaten by cassowaries.

A Fig Parrot eating figs

Various mammals, such as bats and rodents, are also well known vectors. Australia seems to lack a high diversity of seed dispersing mammals. Most noticeably missing from our rainforests, and most obvious in other rainforests around the world, are the monkeys and other primates. The equivalents in the Australian rainforests are the various species of possums. Probably even more effective are the Flying Fox or Fruit Bats. They are some of our most interesting and underrated of mammals. They are often attracted to fruits that are duller or lighter colored, juicy and sometimes strong smelling. Their ability to fly means the seeds are often widely dispersed.

A coppery brushtail eating fruit