GENERAL FEATURES OF ANIMALS
Abstract
All animals belong to the phylum animalia and they share basic characteristics which differentiate them from other organisms in the phyla such as plantae, monera and prototista. Some of these characteristics include the mode of feeding which is heterotrophic (depend on other animals, plants and algae as a source of food). Animals have a multicellular cell organization with their cells having only a cell membrane but lacking a cell wall. The third feature of all animals is that they are able to move or they have a locomotory capability. Sexual reproduction is prevalent in most animals with a few exceptions like hydra which can reproduce asexually. Lastly, all the animals show a distinctive feature and patterns showing their embryonic development
General Features of Animals
Phylogenetic studies support that all animals have a single ancestral origin. Sponges are believed to have originated from a choananoflagellate, a type of protist. The evolution of all the animals is believed to have started from sponges. Although all the animals share several features, distinguishing features exist which enable taxonomists in the process of classification.
Heterotrophic nutrition in animals differentiates them from autotrophic algae and plants which synthesize organic compounds from inorganic molecules for energy production and life sustenance. Heterotrophes include carnivores such as lions, wolves, cheetahs and leopards herbivores such as giraffes, goats, elephants and zebras and omnivores such as man. Other animals like hyenas, vultures and earthworms which feed on dead organisms are generally referred to as detrivores. Heterotrophic nutrition shared among all the animals including man, giraffes, goats, lions, wolves, cheetahs and leopards is known as heterotrophism.
All animals have a multicellular body organization with their cells differentiating into specialized types during development each type performing a specific task. The brittlestar has highly specialized multicellular body organization with the arms serving as locomotory structures and grasping of the prey. The arms are also specialized in sensory functions. Although higher plants are multicellular, animals have the most complex multicellular organization with highly developed sensory and excretory systems. Heterotrophic organisms like protozoa were initially classified as small animals but they were later grouped under the phylum Protista since they were unicellular.
Animal cells lack a rigid cell wall which is mostly found in plants and bacteria. As a result, animal cells are flexible and can move easily. For example, the cancer cells which metastasize to other parts of the body do so because they are flexible. The lack of cell walls in animal cells ensures that there is significant cellular communication through membrane receptors and intercellular junctions. Animal cells such as erythrocytes are involved in the transport of oxygen all over the body and can penetrate into capillaries. This flexibility is only achieved because of the lack of a cell wall.
Animals such as butterflies can fly actively using their wings for locomotion. The ability to move is linked to the flexibility and the highly developed nervous and muscular systems. Humans can support themselves and move due to the highly developed skeletal and muscular system. Snakes and fish which belonging to the class reptilia and pisces respectively utilize their muscles or myotomes to move.
The diversity in terms of forms and habitats is observed in animals. There are several forms of animals which are classified into two categories vertebrates and invertebrates. The invertebrates which include millipedes dont have a backbone and comprise up to 99 percent of all animals on earth. Animals also have diverse habitats for example the jellyfish which belong to phylum of cnidaria live in the sea. Animal phyla like chordata, mollusca and arthropoda are very successful.
Animals reproduce sexually and exhibit a typical embryonic pattern of development. Usually, a zygote undergoes mitosis to form a morula. The morula will develop to a blastula then to a gastrula which determines the diversity of all animals. The gastrula develops into a whole organism with complex tissues, group of cells specialized in performing specific functions. The muscle tissues support all the movement requirements of animals. Other tissues include the nervous and blood tissue which perform the signal conductance and transport in the body respectively. These general features of animals show how far different they are from other phyla of organisms.
All animals belong to the phylum animalia and they share basic characteristics which differentiate them from other organisms in the phyla such as plantae, monera and prototista. Some of these characteristics include the mode of feeding which is heterotrophic (depend on other animals, plants and algae as a source of food). Animals have a multicellular cell organization with their cells having only a cell membrane but lacking a cell wall. The third feature of all animals is that they are able to move or they have a locomotory capability. Sexual reproduction is prevalent in most animals with a few exceptions like hydra which can reproduce asexually. Lastly, all the animals show a distinctive feature and patterns showing their embryonic development
General Features of Animals
Phylogenetic studies support that all animals have a single ancestral origin. Sponges are believed to have originated from a choananoflagellate, a type of protist. The evolution of all the animals is believed to have started from sponges. Although all the animals share several features, distinguishing features exist which enable taxonomists in the process of classification.
Heterotrophic nutrition in animals differentiates them from autotrophic algae and plants which synthesize organic compounds from inorganic molecules for energy production and life sustenance. Heterotrophes include carnivores such as lions, wolves, cheetahs and leopards herbivores such as giraffes, goats, elephants and zebras and omnivores such as man. Other animals like hyenas, vultures and earthworms which feed on dead organisms are generally referred to as detrivores. Heterotrophic nutrition shared among all the animals including man, giraffes, goats, lions, wolves, cheetahs and leopards is known as heterotrophism.
All animals have a multicellular body organization with their cells differentiating into specialized types during development each type performing a specific task. The brittlestar has highly specialized multicellular body organization with the arms serving as locomotory structures and grasping of the prey. The arms are also specialized in sensory functions. Although higher plants are multicellular, animals have the most complex multicellular organization with highly developed sensory and excretory systems. Heterotrophic organisms like protozoa were initially classified as small animals but they were later grouped under the phylum Protista since they were unicellular.
Animal cells lack a rigid cell wall which is mostly found in plants and bacteria. As a result, animal cells are flexible and can move easily. For example, the cancer cells which metastasize to other parts of the body do so because they are flexible. The lack of cell walls in animal cells ensures that there is significant cellular communication through membrane receptors and intercellular junctions. Animal cells such as erythrocytes are involved in the transport of oxygen all over the body and can penetrate into capillaries. This flexibility is only achieved because of the lack of a cell wall.
Animals such as butterflies can fly actively using their wings for locomotion. The ability to move is linked to the flexibility and the highly developed nervous and muscular systems. Humans can support themselves and move due to the highly developed skeletal and muscular system. Snakes and fish which belonging to the class reptilia and pisces respectively utilize their muscles or myotomes to move.
The diversity in terms of forms and habitats is observed in animals. There are several forms of animals which are classified into two categories vertebrates and invertebrates. The invertebrates which include millipedes dont have a backbone and comprise up to 99 percent of all animals on earth. Animals also have diverse habitats for example the jellyfish which belong to phylum of cnidaria live in the sea. Animal phyla like chordata, mollusca and arthropoda are very successful.
Animals reproduce sexually and exhibit a typical embryonic pattern of development. Usually, a zygote undergoes mitosis to form a morula. The morula will develop to a blastula then to a gastrula which determines the diversity of all animals. The gastrula develops into a whole organism with complex tissues, group of cells specialized in performing specific functions. The muscle tissues support all the movement requirements of animals. Other tissues include the nervous and blood tissue which perform the signal conductance and transport in the body respectively. These general features of animals show how far different they are from other phyla of organisms.
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