Animals Directory

Posts Tagged ‘First animals’

Are all those animals that reproduce by eggs, including in this category, the vast majority of insects, reptiles, amphibians, fish, birds and all species of mammals known as “Remonstrate “(like the platypus and Chicana).

These eggs can be placed in dry, damp or in the mother (viviparous). For dry environments, the egg is fertilized in the time of post. This does not happen in the case of wet environments, where the eggs are not fertile yet, and once placed in water, the male sheds his sperm over them, completing fertilization. In the case of viviparous, the eggs develop and hatch inside the mother’s body, leaving your body to live young.

The vast majority of the eggs are very fragile and have a good chance of food for predators, so parents are oviparous jealous of their unborn babies and their caregivers cautiously, especially in the case of birds, where this aspect is very root. Not so in the case of some species of reptiles (like rattlesnakes), which may have attitudes of cannibalism, eating their own eggs.
The moment where he breaks the egg and the baby is born from within, is called hatching, and represents the birth of the baby.

Note that in the prehistoric age, the first animals on earth (fish) are reproduced in this way and 450 million years ago, the first mammals appeared only 180 million years ago, ie about 270 million years later.

As befits the first vertebrates, are aquatic and breathe through gills is mainly located in recesses of the pharynx. Your way to navigate the environment is based on a hydrodynamic shape, with lateral movements of body limbs that are aided by fins. The group of fish is very diverse and includes such diverse forms as lampreys, sharks and tuna, already reaching about 30,000 known species.

Fish are the first animals originated from evolution, which originated around the beginning of the Cambrian. No one knows for certain exactly where to set its origin. The most primitive group of fish, agnates who do not have jaws, includes within its group to lampreys and hag fish.

The group of fish can be classified as:

Chondrichthyes or cartilaginous fishes: the type of sharks, rays and chimeras are characterized by having gill slits externally visible and only a skeleton made of cartilage.

Bony: possessing a bony skeleton and gills protected by a cover. Many morphological, anatomical and physiological differ both groups.

The Hypochondriacs are a very primitive group of vertebrates, but evolutionarily very successful, as the Sharks are ancient animals that have not changed much since its inception and yet they are perfectly adapted to the present.

Terrestrial vertebrates diverged from lungfish, including some of the earliest forms are half way between our concept of fish and amphibian.