Invertebrates. Animal Kingdom. Fauna. Zoology.

Invertebrates, whose name means "without a backbone", include almost 2 million animal species, more than 90% of those that exist in the world, and several tens of thousands in Aragon and comprise 25 of the 26 Types into which the Animal Kingdom is divided. The name of invertebrates does not have any scientific value, but is a generic term for those that are not vertebrates.

Its enormous variety ranges from unicellular organisms (such as Protozoa), to the complex forms of insects.

Another trait of many species of Pyrenean invertebrates (and several vertebrates) is the restricted distribution adapted in a given biotope, these animals are very sensitive to change. The damage that man causes, more rapidly every day, in the nature of our country, can end (and probably have already ended in some cases) with unique species in the world, unrepeatable products of millions of years of natural selection.

A simplified classification of invertebrates could be the following:

TYPE
Spongiaries	They have no nervous system, no muscles or sensory organs. They reproduce both axesually (budding) and sexually. They are aquatic animals, especially in the sea.
coelenterates	They present two corporeal structures: polyp and medusa. The polyp reproduces by budding and the jellyfish sexually.
Asquelmintos	Its name means "round worms" by derivation from the Greek. They have a single cavity where the organs of their body are located, without segments or rings.
Flatworms	Its name means "flat worms" by derivation from the Greek. They are able to move by themselves and reproduce by mating.
Annelids	They are segmented worms, present in diverse environments (submerged land, fresh water, sandy seabed). It has a nervous system, excretory and circulatory system. The side bristles help them to move.
Echinoderms	They have radial symmetry, that is, their organs are arranged around a central axis. They are also covered by plates. They are found in marine environments.
Mollusks	They are endowed with complex circulation and sensory systems They consist of a head, a foot, a visceral sac, a skin and a shell.
Arthropods	Arthropod means jointed leg. They have segmented bodies covered by an external flexible skeleton and jointed legs. They are a group of animals that includes insects, spiders, scorpions and centipedes, all of them present in Aragon.



Other information about fauna in Aragón:

A small list of species in Aragon would be the following:

Vertebrates	Invertebrates
Mammals Red squirrel. Bear. Fox. Artiodactyl Ungulates Deer. Wild pig. Birds Classification of Birds Storks. Capercaillies. Reptiles Amphibians Urodelos.    Marbled Triton.    Webbed Triton.    Pyrenean triton. Anurans. Fishes	Metazoans Arthropods Myriapods Insects Arachnids Spiders Crustaceans Annelids Worm Molluscs Asquelmintos Platelmintos Celentereos Porifera Protozoa
images about the fauna in Aragon.    photographs on invertebrates.    beneficial animals for agriculture.