Azaz

Interactions between biotic components
3 types of symbiosis
i) commensalism - epizoics and epiphytes ii) parasitism iii) mutualism

Commensalism - interaction between one organism (commensal) benefits and the other (host) neither benefits nor harmed
Epizoics - animals which live as commensals on the outside of other animals
Epiphytes - plants which grow on the surface of other plants to obtain sunlight and air (do not absorb food)

A shark and remora fish.
The remora fish attaches itself to the shark to get a free ride, protection and scraps of food left by the shark. The shark does not benefit from this relationship.

Example of the epiphyte : Bird's nest fern

Parasitism is an interaction between two organisms in which one organism (parasite) benefits and the other (host) is harmed.
Ectoparasites - parasites which live on the outside of the host
Endoparasites - parasites which live inside their hosts

Louse (lice pl.) sucks blood from the host

Tapeworms live inside the intestines of humans. They obtain digested food and shelter.
The host suffers from malnutrition.

Mutualism - an interaction between two organisms in which both benefit

Sea anemone and hermit crab.
Sea anemones usually attach themselves onto the shell of a hermit crab. They get free rides and leftover food. The hermit crab receives protection against predators from sea anemones.

Saprophytism - a type of interaction in which a living organism obtains food from the dead and decaying remains of other organisms
Saprophytes - plants which feed on decaying matter
Saprozoic - animals which feed on decaying organic matter
Mushrooms growing on decaying wood.

Prey-predator - interaction between a predator which hunts and eats another animals (prey).

An eagle and a rat.
Competition
Intraspesific - among the same species
Interspecific - among different