Aragon > Naturräume in Aragon > Fauna
Fish are vertebrate animals of aquatic life of which there are about 20,000 known species.
Aragon has no sea, therefore the number of species, exclusively freshwater is much smaller.
fish swimming
They almost always have elongated shapes that allow them to easily move in the water.
The most common forms are: Fusiform (spindle form), flattened and cylindrical.
Your skeleton can be bony or cartilaginous.
The common characters are:
Reproduction is usually through external fertilization, although some species have a copulatory organ.
The senses of taste, smell, etc., usually have them on the skin.
The circulation in fish is closed, simple (from the heart to the gills) and complete (without a mixture of venous and arterial blood).
Breathing in fish is gill.
Water enters the oral cavity and passes through the gills, where it takes the dissolved oxygen in the water.
Cyclostoms or Agnatos |
They are not true fish. They have no lower jaw. They have no vertebrae or bones of any kind. They only have a dorsal cord. |
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Elasmobranchs | Fish with cartilaginous skeleton. Skin covered by dermal denticles. They have no swim bladder. |
Teleost | Fish with partial or fully ossified skeleton. With scales and swim bladder. This group includes most of the fish. |
The primitive Ostracoderms evolved from the Amphibian and developed until they reached the primitive Ichtyostega, the first vertebrate that came out of the water.
The other vertebrate groups evolved from these primitive amphibians.
From the first placoderm fish, vertebrates evolved in various branches that have given rise to current vertebrates.
A small list of species in Aragon would be the following:
Vertebrates | Invertebrates |
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MammalsBirdsReptilesAmphibiansFishes |
MetazoansProtozoa |
images about the fauna in Aragon. photographs on invertebrates. beneficial animals for agriculture. |