Cryptozoa are small invertebrate animals that live underneath the leaves, rocks and fallen logs on the rainforest floor.

These include animals that can also be found in temperate forests, such as snails, slugs, springtails, mites, millipedes and centipedes, as well as some animals that live only in the tropical rainforest.

Although leaves fall in the tropical rainforest throughout the year, there is less debris there than in temperate forests, where leaf fall is seasonal. This is because in the tropical rainforest, high temperature, humidity and the activity of termites ensure that litter is rapidly decomposed and then reused by animals and plants.

Velvet Worms

The velvet worm can be found throughout all of the Earth's tropical rainforests.

It is a carnivorous predator. However, it will scavenge dead insects.

Velvet worms can range from 0.5 to 20 centimeters long, although they average about 5 centimeters (2 inches).

They have two large slime glands that extend over half the length of the body and open onto two small papillae near the mouth.

If a predator attacks, the velvet worm will eject slime. It is not known whether this thickening slime is also used to restrain prey. Velvet worms dehydrate rapidly so need tropical rainforest's high humidity.

Land Planarians

Land planarians need high humidity to survive.

Concentrated in the tropical rainforests of South America and Southeast Asia, they are sometimes established in hothouses, having been introduced on tropical plants.

One species, Bipalium kewense, was first discovered in the greenhouses of Kew Gardens in London and only later found to be of tropical origin.

Often brightly hued, with a body that resembles a ribbon, these nocturnal carnivores form a lime trail as they glide along.

They feed by wrapping themselves around their prey, liberally coating it with slime. They then either engulf it or pour digestive enzymes onto it and then suck up the "soup" that is formed.

Spiders

Many large spiders, such as the trapdoor spider and the birdeater spider live on the rainforest floor.

Smaller specialist spiders also flourish there. The ogre-faced spider, constructs a supporting web on low vegetation close to the rainforest floor and over an ant trail.

It hangs from this web, using its rear two pairs of legs. In its front two pairs of legs, the ogre-faced spider holds a net of teased silk that it dabs at passing ants, picking them off the ground.

Insects

Cockroaches, beetles, and crickets and many other insects inhabit the floor of the tropical rainforest.

Some, such as the web spinner, produce silk to construct tunnels in which to live.

Insects and Plants

Insect life in the tropical rainforest is extremely diverse. This is partly due to the diverse plant life that also exists in that environment.

Plants and insects have evolved together in the rainforest

Some insects eat only certain plant seeds. Therefore, they are usually found beneath the seed-producing tree, eating or killing most of the seeds there.

Seeds that are dispersed away from the parent tree and its congregation of seed-eating insects have a greater chance of surviving. This means that it is advantageous for individual trees of the same species to be widely separated.