Home News BIOLOGY FORM FOUR TOPIC 3: CLASSIFICATION OF LIVING THINGS.

BIOLOGY FORM FOUR TOPIC 3: CLASSIFICATION OF LIVING THINGS.

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.
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.

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