KINGDOM ANIMALIA (Characteristic feature)

KINGDOM ANIMALIA (Characteristic feature)

1. All are multicellular organisms
2. DNA is located in nucleus enclosed with nuclear membrane
3. Cells have no cell walls
4. All possess nervous systems except the sponges
5. All possess true tissue except sponges
6. Feeding is heterotrophic

The Kingdom is divided into two major groups

(i)  INVERBRATA: These are groups of animal without backbone

(ii)  VERTEBRATA: These are groups of animal that have backbone

The classification of animals into smaller categories is based on features such as:

(i)         Body Symmetry

(ii)        Body design

(iii)       Body cavity

Body symmetry is based on the fact that the body of the animal has similar or corresponding parts in size, shape, and position on opposite sides of a dividing line or a median plane

Types

1. Radial symmetry means the body of the animal can be cut along its axis in any place to give two identical halves
2. Bilateral symmetry means the body of the animal can be cut along its axis in only one place to give two identical halves.

Body design is the way the body of the animal is shaped or framed, whether it has one or two exits

1. Sac-like body design: Those animals that have a single opening (mouth) that leads to the gut cavity
2. Tubular body design: Those animals have a double opening like tube with gut opening at the anterior (mouth) and posterior (anus)

Body Cavity: A developing embryo of an animal has a primary layer of cells called the germ layer that differentiates to form various body parts. The tissue of primitive animals are derived from two layers of cells, the ectoderm and endoderm. Such an animal is called a Diploblastic animal e.g. Hydra.

Most animals are derived from three germ layers: ectoderm, mesoderm, and endoderm, such animal are called triploblastic animals.

Animal that have three germ layers can be further derived into:

• Acoelomate: animal without body cavity
• Pseudo-coelomate: animal with false body cavity
• Acoelomate: animal with true body cavity

The member of phylum invertebrate

1. PORIFERA (Characteristic features)

– These are unicellular aquatic animals that usually attached to rocks or shell of other animals in colonies

– They are primitive animals that lack specialized tissue such as organs or system

– They have radial symmetry

– They have a single opening leading to internal cavity

Examples are the sponges which are vase-shaped with a symmetrical body.

2. Phylum CNIDARIA OR COELENTERATA

The coelenterates are aquatic organisms that include the sea anemone, jelly fish and corals which are marine organisms, but hydra is found in freshwater

Characteristics

– They are multicellular organisms

– They have radial symmetry

– They have only one body cavity called the enteron

– They have two distinct body layers (diploblastic), ectoderm and endoderm.

– They have soft, jelly-like bodies

– They reproduce asexually by budding

– They have one opening called the mouth, no anus

– They have tentacles and stinging cells used for capturing their prey (Nematocyst)

– They have specialized cells such as nerve, sensory, and absorptive cells.

3. Phylum Platyhelminthes (Flatworm)

This group consists of the flatworms, such as the planaria, flukes and tapeworms.

Characteristics

– They possess soft, flat and unsegmented body

– They have bilateral body symmetry

– They have no body cavity or lumen

– Their bodies is made up of three layers (triploblastic) ectoderm, mesoderm and endoderm

– Most flatworms are hermaphrodites and reproduce sexually

– Some of them are parasites in man and other animals

4. Phylum Nematoda (Roundworms)

The nematodes are the hookworms, Ascaris lumbricoides and guinea worms

Characteristics

– They have round and cylindrical bodies

– They lack a body cavity i.e. they have a pseudo-coelom body cavity

– They have bilateral body symmetry

– Some are hermaphrodites while some reproduce sexually.

5. Phylum Annelida

The annelids are the earthworm, leeches, and tubeworms

Characteristics

– They have a true body cavity or coelom

– They have a metameric segmentation, which means their body is both internally and externally segmented, a feature that distinguishes them from flatworms. Metameric segmentation means that the body is divided into segments by position but has identical organs.

– Some are aquatic while others are terrestrial

– Annelids reproduce sexually and many are hermaphrodites

– They are triploblastic animals

6. Phylum Mollusca

The member of this phylum includes squid, mussel, periwinkles, snails, oysters, octopuses, and slug.

Characteristics

– They have unregimented bodies

– They have tentacles on their heads

– They possess muscular foot adapted for crawling or borrowing

– Their body is covered by soft-tissue called mantle

– Some of them have calcerous shells e.g snail while some are without e.g. octopus

– Some are aquatic, while some are terrestrial

– They have oculiferous tentacles, which are used for sensitivity

7. Phylum Arthropoda

This is the largest group in animal kingdom they have a distinct head with complex muscular system. The phylum is divided into four classes

1. Crustacea e.g. crab, crayfish, prawn, lobster.
2. Insecta e.g. all insects grasshopper, ant, termite e.t.c.
3. Arachnida e.g. spider, scorpion, miles and tick
4. Myriapoda e.g. centipede and millipede

Characteristics

– They have segmented bodies

– They have hard, rigid exoskeleton made of chitin bodies

– They have jointed appendages or jointed legs used for feeding, movement, reproduction or as sensory organs.

– They exhibit moulting or ecdysis i.e. shedding their exoskeleton at interval to permit growth

– Their bodies are divided into two or three segments such as head, thorax and abdomen which may be fused together in some members.

– They have bilateral body symmetry

– They are triploblastic animal

– They have various means of respiration e.g. gills, trachea, lung book or body surface.

8. Phylum Echinodermata

These are the starfish, sea urchins, sea cucumbers, and bristle star

Characteristics

– They have radial body symmetry

– They are mostly marine

– They are triploblastic animals

– They have neither  nor brain

– Their body is not segmented

– They have true feet, which are used for movement

9. VERTEBRATA

This is a subphylum of the phylum Chordata. It comprises five classes. They are:

PISCES (fishes)

AMPHIBIA (Amphibians)

REPTILIA (Reptiles

AVES  (all birds)

MAMMALIA (mammals)

General Characteristics of Vertebrate

– They possess an internal jointed skeleton made up of cartilage or bone

– They all have bilateral symmetry

– The body is divided into head, trunk and tail

– They have two pairs of limbs (pectoral and pelvic) limbs.

– They have well- developed central nervous system with brain

– They have a closed blood system

– They possess skin which may be naked or have a covering of scales, feathers or hairs.

1. CLASS PISCES (OSTERITHY)

The Pisces include all groups of fish, and they show good adaptation to aquatic life. Fishes are of two types

• Bony fish: These are fish with bony skeleton e.g. Tilapia, Salmon, Mackerel e.t.c.
• Cartilagenous fish: These are fishes whose bones are soft e.g. dry fish, shark, rays e.t.c.

Characteristics

– The body is covered by scales but few are without scales

– They possess fins which are used for movement in water

– They use gills for gaseous exchange

– They are poikilothermic or cold blooded animal meaning that their body temperature varies with that of their environment

– They have swim bladder for buoyancy

– They have lateral line for detection of vibration

– They have streamlined body shape for easy movement in water

– They are oviparous animal meaning that they lay egg which develop to adult stage outside the body of the female

             CLASS AMPHIBIA

They are the first vertebrates to adapt to life on land and water. The member includes toad, frogs, salamander and newts

Characteristics

– They are poikilothermic animals

– They have two pairs of limbs-fore limbs and hind-limbs.

– They have naked or moist glandular skin with no external scales

– They exhibit dual life i.e. they can live both on land and water

– They carry out gaseous exchange with gills at tadpole stage of life and with lungs, skin and mouth at adult stage

– They are oviparous using external fertilization

             CLASS REPTILIA

The reptile includes all reptiles with dry skin with scales or bony plate that resist loss of water from the body. They are the first animals to have a copulatory organ (penis) for the purpose of internal fertilization. Examples are crocodile, lizard, wall gecko, snake e.t.c.

Characteristics

– They are poikilothermic animals

– They have dry skin covered with scales

– They all breathe with lungs

– They are oviparous animal

– They have homodont dentition meaning having set of teeth that are the same in shape and function.

– They use sexual reproduction with internal fertilization

– Some are aquatic animal e.g. crocodile and turtle while others are terrestrial

CLASS AVES (Birds)

The aves include all types of birds. They are mostly adapted to aerial life by means of wings which is a modification of the forelimb. Examples of birds are pigeons, domestic fowls, ostrich, ducks e.t.c.

Characteristics

– They are homoeothermic or warm-blooded animal,s meaning they have a constant body temperature, it doesn’t change even when the temperature of its environment rises.

– The entire body of a bird is covered with feathers except the bird legs which are covered with scales

– The mouth is extended to form the beak which is used for feeding

– They have rigid hollow bones with air sac which make them light during flight

– They use internal fertilization

– They use lungs for respiration

– The fore-limbs modified to wings which are used for flight

– They are toothless but use their beak for feeding

CLASS MAMMALIA (all mammals)

The mammals are the most advanced in the animal kingdom. They have two body cavities which is divided into two by a muscular sheet called diaphragm

Characteristics

– They are homeothermic animal

– Their bodies are covered with hair or furs

– They have heterodont dentition meaning having a set of teeth that are different in shape and function

– Their thoracic cavity is separated from the abdominal cavity by the diaphragm

– They use lungs for respiration

– They have well well-developed brain

– They have an external ear called the pinnae

– They are viviparous made of reproduction meaning they give birth to their young ones alive

– They have a fully developed four-chamber heart

– They all have a mammary gland that produces milk to feed their young ones

– They use sexual reproduction with internal fertilization