Cephalopods Mollusks Invertebrates Animal Kingdom. Wildlife. Fauna. Zoology.

Cephalopods are mollusks that are characterized by the great development of the head and the transformation of the foot into tentacles or arms arranged around the head.
These have rows of suckers on their inner surface that make them extraordinarily pressing.

They are very well adapted for swimming and are moved by the expulsion of water by the funnel or siphon they possess.

Decapods have an internal limestone shell and octopuses lack it.

They are very voracious carnivores.
They have an intestinal gland, the ink bag, which serves to escape their enemies.
They also have the power to change color by activating special cells.

Their nervous system is highly developed and they have the most perfected eyes of all invertebrates.
Some have phosphorescent organs.
Cephalopods capture their prey using the suckers that are provided with the tentacles on their inner face. Suction cups usually have a corneal ring and work by practicing the vacuum by the action of a muscular piston.

They can be moved by a jet propulsion system.
They swim backwards violently expelling a stream of water from the mantle cavity through the siphon.
When they are harassed, cephalopods momentarily disorient and blind their pursuer by emptying the ink bag and clouding the water.

Classification of Cephalopods

• Tetrabranchs, with two pairs of gills (Nautilus).
• Octópodos, with a pair of gills (Dibranchs) and eight feet (Octopuses).
• Decapods, with a pair of gills and ten feet. (Squid, cuttlefish).

Tetrabranchs

Tetrabranchs have two pairs of gills and there are only three living species, descendants of a group that lived 500 million years ago.
They are the only cephalopods that have an external shell, formed by numerous chambers filled with a mixture of gases that facilitate and regulate their flotation.
Of these cameras, the animal only occupies the last.
The tentacles are very primitive retractable filaments and have no detritus bag.
The eyes are simpler than those of the other cephalopods, but they also have crystalline and cornea.

Pigment cells, when contracted, produce a change in color in the cephalopods.

The Nautilus has a reproductive arm that emerges from the male to be picked up by the female in the paleal cavity, where fertilization takes place.

The octópodos

These cephalopods have no shell remnants.
They have eight very long and sensitive arms equipped with a double row of suction cups that they use to locate their prey and catch them.
His body is shaped like a sack without fins.
There are octopuses that can measure up to 3 meters in size.
They live perfectly in coastal areas, but there are some that live in depths of more than 5,000 meters.

The female argonaut develops a pearly shell where it deposits large numbers of eggs.

The decapods

These cephalopods have ten very prehensile tentacles, eight of which are short with rows of suckers and two much longer with suckers only at their ends.
They have a spongy inner limestone shell on the back, called "jibión".
They are, like all cephalopods, voracious carnivores, with their mouths provided with a "parrot beak" and a radula.
His skin has many "chromatophores" with which they change color.

The eye of cephalopods

It is the most evolved of invertebrates and its structure, very perfected, is reminiscent of that of the vertebrate eye, possessing practically all its elements.

There are giant squids of large dimensions, having observed one that was 18 meters long, thus being the largest living invertebrate.
They inhabit the great marine depths and it is food preferred by sperm whales, with which it fights violent combats.
Sepia reproduction is sexual.
The male introduces a modified arm into his paleal cavity and removes the spermatophore with him, moving them to a small cavity that the female has, called a copulatory bag. In it the female throws her eggs, which are fertilized and expelled. These are hooked to aquatic plants.

Other information about MOLUSCOS

• Introduction
• Monoplacóforos
• Poliplacóforos
• Escafópodos
• Gastropods  
  • Slugs or Limacos
   
  • Snails
• Bivalves or lamelibranchs
  • Freshwater clams
  • Margaritona (Margaritifera auricularia)
  • Zebra mussel (Dressenia polymorpha)
• Cephalopods



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.



Also Aragon enjoys a diverse and varied Nature where passing by plants, animals, Geology, or landscapes we can arrive at a fantastic bestiary that lives in its monuments.

The information will not be complete without a stroll by its three provinces, with shutdown in some of its spectacular landscapes like Ordesa, the Moncayo, Monegros or by opposition the Ebro.

Also you can dedicarte to the intangible ones: from the legend compilation that also does to universal Aragon.