Animalia: Animal Kingdom | Biology for JAMB PDF Download

Classification

• The animal kingdom is classified into different major phyla, including Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda, Mollusca, Echinodermata, and Chordata.
• Each phylum consists of various classes, orders, families, genera, and species.

Characteristics

• Animals are multicellular eukaryotic organisms without cell walls.
• They exhibit heterotrophic mode of nutrition, obtaining nutrients by consuming other organisms.
• Animals are typically motile, capable of moving from one place to another.
• They have specialized sensory organs for receiving and processing information from the environment.
• Animals reproduce sexually, although a few may also reproduce asexually.

Porifera

• Porifera, also known as sponges, are simple multicellular organisms.
• They are characterized by a porous body with specialized cells called choanocytes.
• Sponges are mostly marine organisms and have no true tissues or organs.

Cnidaria

• Cnidaria includes organisms such as jellyfish, sea anemones, and corals.
• They possess specialized stinging cells called cnidocytes for capturing prey and defense.
• Cnidarians exhibit radial symmetry and have a sac-like body plan.

Platyhelminthes

• Platyhelminthes, or flatworms, are soft-bodied organisms.
• They can be free-living or parasitic.
• Flatworms have a bilateral symmetry and a simple digestive system.

Nematoda

• Nematoda, commonly known as roundworms, are unsegmented worms.
• They are found in various habitats, including soil, freshwater, and marine environments.
• Roundworms have a cylindrical body with a complete digestive system.

Annelida

• Annelida consists of segmented worms like earthworms and leeches.
• They exhibit a segmented body with distinct segments repeating along the length.
• Annelids have a well-developed coelom and a closed circulatory system.

Arthropoda

• Arthropoda is the largest phylum, including insects, spiders, crustaceans, and others.
• They have jointed appendages, an exoskeleton, and a segmented body.
• Arthropods exhibit a wide range of adaptations and are highly diverse.

Mollusca

• Mollusca encompasses organisms like snails, clams, squids, and octopuses.
• They have a soft body protected by a hard shell in some species.
• Mollusks have a muscular foot, a mantle, and often a radula.

Echinodermata

• Echinodermata includes organisms such as starfish, sea urchins, and sea cucumbers.
• They have a spiny exoskeleton and a unique water vascular system for locomotion and feeding.
• Echinoderms exhibit radial symmetry as adults.

Chordata

• Chordata is the phylum to which humans and other vertebrates belong.
• They are characterized by the presence of a notochord, dorsal nerve cord, and pharyngeal gill slits.
• Chordates have a well-developed internal skeleton and a complex body organization.Fig. Classification of Animal Kingdom