Kingdom Animalia 

The word ‘animal’ is derived from the Latin wordanimaliswhich means ‘having breath’. The Kingdom Animalia is characterized by eukaryotic and heterotrophic organisms. They are multicellular and lack cell wall. They 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 exhibitwell developed sensory and neuromotor mechanism. Most of the organisms are capable of locomotion. Reproduction is by copulation of male and female which is followed bydevelopment in embryonic stages.
Zoology - Kingdom Animalia

General and Distinctive Features of the Kingdom Animalia

Explain general and distinctive features of the kingdom animalia
Distinguishing characteristics of the Kingdom Animalia include:
  • Cell type – Eukaryotes
  • No cell wall
  • Nutrion – Heterotrophic, ingestion
  • Body form – Muticellular,(invertebrate/ vertebrate)
  • Nervous system – primitive to advanced sensory systems
  • Reproduction – All sexual, some also asexual
  • Locomotion – Ability to move at some point and time throughlife cycle
General characteristics of the Kingdom Animalia are as follows:
  • 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.
  • There are around 9 to 10 million animal species that inhabit the earth. Only 800,000 species are identified.
  • Biologists recognize 36 phyla in the animals kingdom.
  • 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 major Phyla of the Kingdom Animalia

Mention the major phyta of the kingdom animalia
Kingdom Animalia has approximately 36 sub-divisions known as ‘phyla’. Each phyla share particular properties structurally and functionally which together separate it from other phyla. Below are the most common phyla classified under traditional biological methodology
  • Phylum Porifera– They are primitive organisms, most of them are salt-water sponges. They do not have organs or nerve cells or muscle cells. Approximately, 8,000 species exist today. Example:Sycon, Euspongia, Spongilla.Phylum Coelentrata (Cnidaria)- This group is composed of jelly-fish and other lower aquatic animals. Approximately, 15,000 species exist today.Example:Aurelia, Adamsia.
  • Phylum Platyhelminthes– This group consists of flat worms. They inhabit both marine and fresh water habitats and they are mostly endoparasites found in animals. Example:Taenia, Fascicola.
  • Phylum Aschelmeinthes– It is a group of round worms, most of them are parasites. This phylum consists of about 80,000 parasitic worms.
  • Phylum Annelida– They are present in aquatic, terrestrial and are free-living or parasitic in nature. This phylum comprises of segmented worms. Example: Earthworm, Leech etc.Phylum Arthropoda- This is the largest phylum which consists of insects. There are over 1 million species of insects existing today. Example: Locusts, Butterfly, Scorpion, Prawn.
  • Phylum Mollusca– It is the second largest phylum. They are terrestrial and aquatic. Example:Pila, Octopus.
  • Phylum Echinodermata– This consists of sea stars and sea urchins. There are about 6,000 species. Example:Asteria,Ophiura.
  • Phylum Chordata– Animals of this phylum have a characteristic feature of presence of notochord, a dorsal hollow nerve cord and paired pharyngeal gill slits. Within this phylum advanced group called vertebrates which include fish, amphibians, reptiles, birds and mammals.


Phylum Chordata
Phylum chordata is found in the kingom Animalia. Members found on phylum chordata are fish, frog, lizard, birds, rats etc.
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General and Distinctive Characteristics Features of the Phylum Chordata
Explain general and distinctive characteristics features of the phylum chordata
General Distinctive Characteristics of Phylum Chordata are:
  1. They have a notochord in the embryonic stage. If they notochord persists throughout the life span, it may be surrounded by a vertebral column as in lungfish or it may both be surrounded by a vertebral column as in some chordata
  2. Their nerve cord is hollow and placed dorsally to the gut
  3. They have gill slits at least during the embryonic stage
  4. They have tail which is behind the anus
Classes of the Phylum Chordate
Mention classes of the phylum chordate
The phylum chordata consists of six classes which are
  1. Class Chondrichthyes
  2. Class Osteichthyes
  3. Class Amphibia
  4. Class Reptilia
  5. Class Aves and
  6. Class Mammalia
Distinctive Features of Each Class of the Phylum Chordata
Explain distinctive features of each class of the phylum chordata
Distinctive features of Class Chondrichthyes
  1. The skeleton is made up of cartilage
  2. The body is covered with placoid scales
  3. The caudal fin has tow lobes that differ in size
  4. Each pair of gills is in a separate compartment
  5. The mouth and two nostrils are ventrally placed
  6. Males have Copulatory structures called claspers
Distinctive Features of Class Osteichthyes
  1. The skeleton is made up of bones
  2. The body is covered with ganoid scales
  3. The mouth is terminally placed and nostrils are forced on the dorsal surface
  4. All pairs of gills are found in common chamber and the chambers are covered by an operculum
  5. The caudal fin has loves of the same size
Distinctive Features of Class Amphibia
  1. Their skin is always moist example frogs
  2. Their life cycle involves larva form called tadpole
  3. They have gills which are present in the early stages of the development of the tadpole
  4. They have a heart which has three chambers
  5. There is gaseous exchange by gills in the tadpole and in the adult it takes place in the lungs, skin and the mouth lining
Distinctive features of Birds
  1. The body is covered with feathers
  2. The anterior pair of limbs is modified into wings
  3. The mouth is modified into a beak or bill
Distinctive features of Class Mammalia
  1. Their body is covered with hairs
  2. They have mammary glands
  3. They have teeth of different types and shapes
  4. They have diaphragm
  5. Their red blood cells have no nucleus
  6. They have sweat glands. The body temperature of mammals is constant
Structure of Representative Organisms in each Class of Phylum Chordata
Describe structure of representative organisms in each class of phylum chordata
Structure of Amphibians
The body of toad or frog consists of a head and trunk only. The skin is dry and warty in toads and smooth and shiny in frogs. On the head are pair of nostrils and lower eyelids, which are almost immovable.
The fore limbs of toads and frogs are short. They have 4 digits on each hand, as the thumb is missing. The hind limbs are much longer than the front ones and the feet are very large. A thin web of skin, which is particularly well developed in frogs, joins the toes. Adult toads are mainly land animals and usually enter water only to breed.

Example of Specimen found on Class Chondrichthyes

Example of Specimen found on Class Chondrichthyes

Example of Specimen found on Class Aves

Example of Specimen found on Class Mammalia

Example of Specimen found on Class Reptilia
The advantages and disadvantages of Organisms under each Class of Phylum Chordata
Outline the advantages and disadvantages of organisms under each class of phylum chordata
Importance of Amphibians
  1. They are ecologically important
  2. They are used in research specimen
  3. Some amphibians are eaten as food
  4. Some amphibians have unique features. Example abnormally big sizes attract tourists
  5. They have typical characteristics of larger animals hence they are among the most preferred specimens for biological studies
Importance of Class Reptilia
  1. Reptiles act as attractive features e.g. colour of snake
  2. Reptiles are used as a source of food for other species example birds feed on snakes
  3. Reptiles are used in decorations in houses
Disadvantages of Class Reptilia
  1. Can cause death to human beings, for example a snake
Importance of Birds
  1. Flesh of several species is used as food for human beings example chicken, duck
  2. The feathers of birds are used for decorations
  3. Birds are also used for the pollination of seeds and fruit dispersal
  4. Some birds like Ostriches are attractive to tourists
  5. Some species of birds are used for biological control
Importance of Mammals
  1. Most mammals serve as source of food for human beings example cows, sheeps
  2. Mammals help in production of manure example manure from cows, goats
  3. The bones of mammals are used for production of animal charcoal
  4. Most wild animals in national parks and game reserves attract tourists
  5. Some domestic mammals such as cows and donkeys are trained to perform human duties such as cultivation of crops

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