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A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
An aquatic animal is any animal, whether vertebrate or invertebrate, that lives in bodies of water for all or most of its lifetime. [1] Aquatic animals generally conduct gas exchange in water by extracting dissolved oxygen via specialised respiratory organs called gills, through the skin or across enteral mucosae, although some are evolved from ...
Fish are very diverse animals and can be categorised in many ways. Although most fish species have probably been discovered and described, about 250 new ones are still discovered every year. According to FishBase about 34,800 species of fish had been described as of February 2022, [ 5 ] which is more than the combined total of all other ...
Domestication is a gradual process, so there is no precise moment in the history of a given species when it can be considered to have become fully domesticated. Zooarchaeology has identified three classes of animal domesticates: Pets (dogs, cats, ferrets, hamsters, etc.) Livestock (cattle, sheep, pigs, goats, etc.)
Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft).
Marine animals are further informally divided into marine vertebrates and marine invertebrates, both of which are polyphyletic groupings with the former including all saltwater fish, marine mammals, marine reptiles and seabirds, and the latter include all that are not considered vertebrates.
The goat is a terrestrial animal.. Terrestrial animals are animals that live predominantly or entirely on land (e.g. cats, chickens, ants, most spiders), as compared with aquatic animals, which live predominantly or entirely in the water (e.g. fish, lobsters, octopuses), and semiaquatic animals, which rely on both aquatic and terrestrial habitats (e.g. platypus, most amphibians).
Jellyfish, also known as sea jellies, are the medusa -phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals, although a few are anchored to the seabed by stalks rather than being motile. They are made of an umbrella-shaped main body made of ...