Digestive system The digestive system is well differentiated into sections: mouth (with teeth) – pharynx – esophagus – stomach – intestine – anus. The fish have a liver
The skeleton and muscles are part of the musculoskeletal system. The skeleton provides support for the body and organs of movement, protects the most important organs. Due to
The laterally compressed body of the fish has a streamlined shape, which reduces the resistance of the water during their movement. In it, you can distinguish the head,
Fish are divided into two classes – Cartilaginous fish (sharks, rays) and Bony fish (sturgeon, salmon, herring, crucian carp, perch, pike, etc.). The main criterion for such a
Fish are the largest group of vertebrates (about 30 thousand species). Fish are permanent inhabitants of the aquatic environment. They inhabit almost all water bodies of the Earth:
Vertebrates have mastered all habitats and are distributed throughout the globe. They lead an active lifestyle, sometimes making distant migrations. Many vertebrate species reach high numbers. Vertebrates are
More than 40 thousand modern animal species are classified as chordates. These animals are very diverse in external structure, lifestyle and living conditions. General structural features of chordates:
Most insects are solitary. However, there are also social insects: ants, bees, bumblebees, wasps, termites. Social insects live in organized groups (families). The community of these insects is
Some insects, especially blood-sucking ones, are carriers of causative agents of dangerous human and animal diseases. Insects – pathogens and human parasites Malaria mosquitoes are carriers of malaria
