KINGDOM ANIMALIA

KINGDOM ANIMALIA

Kingdom Animalia has several phyla each of which consists of a variety of organisms.

The phyla include

  1. Porifera e.g. sponges-
  2. Coelenterata e.g. hydra
  3. .Platyhelminthes e.g. flat worms
  4. Nematoda e.g. round worms
  5. Annelida e.g. ringed worms
  6. Mollusca e.g. snails
  7. Echinodermata e.g. star fish
  8. Arthropoda e.g. cockroach
  9. Chordata e.g. man

General characteristics

  • Animals carry out locomotion
  • They have heterotrophic mode of nutrition
  • They are multicellular organisms.iv)Their body has a definite shape.
  • They have cells without cellulose but contain true nucleus.

1.Phylum: Porifera –the sponges

The phylumis made of many types of sponges. They have the following characteristics:

  • Possess simple bodies which are hollow and sac-like.
  • They are marine dwellers
  • They are sedimentary or sessile organisms found attached to the rocks or coral reefs
  • Some can live in colonies or individually.
  • They lack a nervous system.
  • They have only one opening in their bodies.
  • They have a body made up of two layers of cells i.e. ectoderm and endoderm.

2.Phylum: Coelenterata (Cnidaria)

They include the following; the jelly fish, sea anemones, hydra and corals.

They have the following characteristics:

  • They are multicellular organisms.
  • They are aquatic or marine organisms.
  • They have soft bodies which are sac-like with body cavity called enteron
  • They have radial body symmetry.
  • They have a single body opening.
  • They have tentacles.
  • They possess specialized cells such the stinging cells used for defense or paralyzing their prey.
  • They have a ring of tentacles for capturing prey.

3.Phylum: Platyhelminthes (flat worms)

The phylum consists of organisms like flukes and tape worms. They have the following characteristics

  • They have dorso-ventrally flattened body
  • They have bilateral body symmetry.
  • They are damp, moist or aquatic dwellers.
  • They are parasitic organisms.
  • They have alimentary canal without mouth.
  • The body wall has three body layers of cells (triploblastic) i.e. ectoderm (outer), mesoderm (middle) and endoderm (inner).
  • The gut is branched to increase surface area over which digested food is absorbed.
  • They are hermaphrodites; have both male and female organs in the same organism.
  • They lack blood circulatory system and because of that, the gaseous exchange occurs by simple diffusion all over the body surface.

The phylum has 3 main classes;

i)Turbellaria e.g. Planarians

  • They are free living flat worms that live in wet soils, fresh water and seas.
  • They have many simple eyes and cilia on the under surface of the body used for movement over stones and weeds.

ii)Trematoda e.g. Liver fluke

  • They live as endo parasites in cattle, goats and man.
  • They have no cilia on their body and lack simple eyes
  • They have suckers used for attachment on to the host.
  • They suck digested food from the host.

iii)Cestoda e.g Tape worm

  • They live as endo-parasites ni the gut of man, muscles of goats, cows and pigs.
  • They have suckers and hooks for feeding and attachment on to the host.
  • They have elongated bodies consisting of segments called proglotids.
  • They absorb digested food directly from the host

4.Phylum: Nematoda ( round worms)

The phylum has the examples like hookworms, pin worms, guinea worms, whip worms and ascaris lumbricoides. They have the following characteristics:

  • They have segmented bodies.
  • They have elongated and cylindrical bodies pointed at both ends.
  • They have closed circulatory system.
  • They have gaseous exchange occurs all over the body surface.
  • They have a complete digestive system with both mouth and anus.
  • Some are parasitic and others are free living.

5.Phylum: Annelida (ring worm)

These are the ringed or segmentedworms e.g. earthworms, leeches, rag worms, lugworms, etc. They have the following characteristics:

  • The body wall has three body layers of cells (triploblastic) i.e. ectoderm (outer), mesoderm (middle) and endoderm (inner).
  • They have true coelom.
  • They havea closed circulatory system.
  • They have gaseous exchange all over body surface.
  • They have complete digestive system with both anterior (oral) and posterior (Anal) openings.
  • They are hermaphrodites and reproduce sexually but they often promote cross fertilization.
  • They are carnivorous and some live as external parasites.
  • They have bodies divided into section called septae.
  • Externally the body shows ring-like segments

6.phylum: Mollusca

The organisms are generally aquatic and live both on fresh water and marine. Examples include snails, slugs, octopus, squids, mussels and oysters. They have the following characteristics:

  • They have soft and unsegmented bodies.
  • Nearly all have shells with exception of octopus and squids.
  • The foot is used for locomotion and attachment to the substratum

7.Phylum: Echinodermata

The organisms are sea dwellers. Examples are bristles star, sea urchin, sea lilies, sea star, star fish, sea cucumber. They have the following characteristics:

  • They have unsegmented bodies.
  • They have radial body symmetry.
  • The bodies have five arms.
  • The body wall has three body layers of cells (triploblastic) i.e. ectoderm (outer), mesoderm (middle) and endoderm (inner).
  • They have feet for locomotion and capturing the food (feeding).
  • They have spiny skin which is a hard plate.
  • They have water vascular system instead of blood circulatory system.Structure of star fish