The amphibian class. Part One

The amphibian class. Part One,

Vegetation flourished in the warm and humid climate of the Carboniferous period. At the same time, the living conditions for fish in closed reservoirs on land often deteriorated sharply: coastal vegetation and aquatic plants, falling into the water of swampy reservoirs, rotted, consuming oxygen. The conditions for food on land were often better than in water: there were huge food reserves (invertebrates that appeared on land back in the Devonian) and there was still no competition among its consumers. Pulmonary respiration originated in fish from different systematic groups, and it exists in many modern fish (lungfish, some ray-finned). However, freshwater brush-finned fish are considered the ancestors of terrestrial vertebrates based on the great similarity in the structure of the skull bones of fossil fish of this group and ancient shelled amphibians. There are also similarities in the structure of bones and fins and the five-toed limbs of land animals. The loss of gills by adult amphibians and the appearance of lungs would not have allowed them to stay underwater for a long time during their life in the reservoir. And on land, the lungs provided full respiration with increased activity.

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Therefore, amphibians developed skin respiration . The function of respiration requires the skin to be moist, which also associates amphibians with water. The senses are changing. The lens of the eye is lenticular, not spherical, since the refraction of light in air is slightly different than in water. Air conducts sound worse than water. There is a need for a membrane that receives sound vibrations in the air, the eardrum, and transmits these vibrations to the inner feeling ear. In the canal of the middle ear, one of the bones of the fish's skull is transformed into an auditory bone, the stapes.


The shape of the fish's body was determined primarily by the physical law of drag in the middle of a moving body. For land animals, the resistance of the environment — the air — does not pose any obstacle, especially since the first animals that emerged from the water could only slowly crawl on land. However, for the animals that came to land, another physical law became the determining factor of body shape - gravity, gravity. That's why fish or other water inhabitants are so different from frogs or other land animals. Amphibians need to form a system of movable supports for movement on land. Get 50 free spins when you register via mobile with promo code for 1xbet no deposit required. Winnings from free spins subject to 40x wagering. Max cashout: $100. Compatible with iOS and Android devices. Includes access to exclusive mobile-only promotions. App users also receive push notifications for special offers. Must verify account before withdrawal. Start playing your favorite slots anywhere, anytime with 1xBet mobile platform.