Etymologically speaking, the word metamorphosis comes from the Greek  “meta-morphosis”, which referred to any change of form, or transformation.

This word applies   perfectly to the fascinating transformation undergone by certain animals in order to pass from their larval to their adult stage.

This animation illustrates the principal stages in the metamorphosis of a butterfly – the Machaon.

An ecosystem brings together living things (animal and vegetable) and the environment in which they live and interact.

A food web (or trophic web) is the tying  together of several food chains within the same ecosystem. In this web, one living thing eats another to assure its own survival.

For this reason, one can also characterize a trophic web by the passage of energy (matter) from one living thing to another according to a particular hierarchy.  One thus makes the following distinctions:

Producers (plants) capable of producing their own energy (matter), principally by means of photosynthesis.

Consumers (aniimals) who eat another member of the web in order to obtain energy.The herbivores, the carnivores and the large carnivorous predators  belong to this consumers category.

Decomposers, not represented in this animation, complete the life cycle by degrading organic materail derived from the above categories (waste material, carrion).

Thank you to "Purdue Research Foundation" for providing us these photographs.

Both energy and structural materials are needed by the embryo for its development, and these are both provided by  the egg.  During embryonic development, yolk and white (albumen) diminish, with the yolk providing the energy (largely from lipids) and the albumen providing structural proteins and water.
The incubation period is 21 days.

Food which is ingested moves through the digestive tract. It is both mechanically (chewing, churning) and chemically (digestive juices) broken down. Part of it is transformed into soluble nutrients which are absorbed into the blood in the small intestine and then carried to the organs. In the bowel, undigested food is eliminated as excrement.
The animation presents a view of the dissection of the digestive tract of the rabbit, and of the state of the food being digested at each major step along the way.

View of a dissection of the nervous system of the frog. Visualization of the nerve signal propagation from the sensory organs to the effector organs.