Kingdom Animalia Definition

 

        Kingdom animalia involves different organisms depending to their habitat characteristics and their reproductive systems and also they are multicellular organisms but they lack cell wall. Kingdom animalia  depend directly or indirectly of plants for their food. Food is ingested and digested in their internal cavity and food reserves are stored as glycogen or fat. Nutrition is holozoic, i.e., by ingestion of food. Animals follow a definite growth pattern, the adults have a definite shape and size. Higher forms of animals exhibit well developed sensory and neuromotor mechanism. Most of the organisms are capable of locomotion. Reproduction is by copulation of male and female which is followed by development in embryonic stages. The following are the general characteristics of kingdom animalia;

 .Animals are eukaryotic, multicellular and heterotrophic organisms.

• They have multiple cells with mitochondria and they depend on other organisms for food.

•  Habitat - Most of the animals inhabit seas, fewer are seen in fresh water and even fewer on land.

• Size - The sizes of animals ranges from a few celled organism like the mesozoans to animals weighing many tons like the blue whale.

• Animal bodies - Bodies of animals are made of cells organized into tissues which perform specific functions. in most animals tissue are organized into complex organs, which form organ systems.

• Cell structure - The animal cell contains organelles like the nucleus, mitochondria, Golgi complex, ribosomes, endoplasmic reticulum, lysosomes, vacuoles, centrioles, cytoskeleton.

• Animals are made up of many organ systems, that aids in performing specific functions that are necessary for the survival of the organism.

• Organ systems are skeletal system, muscular system, digestive system, respiratory system, circulatory system, excretory system, reproductive system, immune system and the endocrine system. 

• Body symmetry - Most of the animals are bilaterally symmetrical, while primitive animals are asymmetrical and cnidarians and echinoderms are radially symmetrical.

• Locomotion - Most animals have the ability to move, they show rapid movement when compared to plants and other organisms.

• Respiration - It is a gaseous exchange of taking in oxygen and giving out carbon dioxide. This process takes place in organs of respiration like the lungs, gills, book gills and book lungs and some animals skin is also used for respiration.

• Digestion - Animals ingest food, and digestion takes place in the internal cavity like the digestive system in animals, in primitive animals vacuoles are for digestion.

• Nervous system - Sensory mechanism and the coordination of the organ systems is carried on by the nervous system. In animals the nervous system comprises of nerve ganglions, or brain, spinal cords and nerves. 

• Circulatory system - The distribution of nutrients, exchange of gases and removal of wastes takes place in the circulatory system. This system comprises of the heart, blood vessels and the blood.

• Excretory system - Removal of wastes from kidneys.

• Skeletal system - support and protection is provided by the skeletal system.

• Reproductive system - Most animals reproduce sexually, by the fusion of haploid cells like the eggs and the sperms.

• Glands of the endocrine system help in control and coordination of the body system. 

        

            The Animal Kingdom is split into several Phyla. Each Phylum group contains organisms that have things in common. Below is a list of some animal Phyla:

    Chordate Phylum: All the animals which have a backbone. Includes: Fish, Reptiles, Birds, Amphibians, and Mammals.

     Arthropod Phylum: All the “jointed legged” animals. All of these animals have an exoskeleton, meaning the skeleton is on the outside of the body. Include: Insects, Arachnids, and Crustaceans.

     Mollusk Phylum: Soft-bodied animals that sometimes have a hard shell. Includes: Snails, Slugs, Octopus, Squid, Clams, Oysters, and Mussels.

     Annelid Phylum: Segmented worms. Includes: Earthworms and Leeches.

     Rotifer Phylum: Tiny, microscopic animals with a wheel-shaped mouth and tiny hairs.

     Nematode Phylum: Very tiny worms with no segments in their bodies. Also called Roundworms.

   Tardigrade Phylum: Tiny, slow-moving animals with four body segments and eight legs. Includes Water Bears.

Cnidarian Phylum: Soft-bodied, jelly-like animals with tentacles and venom glands. Includes: Hydra, Jellyfish, Anemones, and Coral.

Echinoderm Phylum: Often spiny animals, with several “arms” reaching out from the center of its body. Includes: Starfish and Sea Urchins. We do not have these in our area!

Platyhelminthes Phylum: Soft, flat-bodied worms. Includes: Planarians and Tapeworms.