Animal Kingdoms: Invertebrates and Vertebrates

Animal Kingdoms: Invertebrates and Vertebrates

• Kingdom Animalia is broadly classified into Invertebrates and Vertebrates, based on the presence or absence of a vertebral column (backbone).
• Invertebrates lack a backbone.
• Vertebrates possess a backbone.
• Invertebrates are further grouped into eight phyla.
• Vertebrates are divided into five major groups: Pisces, Amphibia, Reptilia, Aves, and Mammalia.
• Invertebrates show a simpler body organization than vertebrates.

Invertebrates: Eight Major Phyla

• Porifera (pore-bearing animals): Simplest multicellular animals; their bodies are made up of loosely connected cells that perform life functions independently. They have no tissues, organs, or organ systems. Examples include sponges (Euspongia and Sycon).
• Cnidaria (hollow sac-like animals): Possess a hollow body cavity with one opening (the mouth). Their bodies are made up of two cell layers and have basic tissue level organization. Examples include hydra, jellyfish, and sea anemones.
• Platyhelminthes (flat worms): Ribbon-like or leaf-like, thin, flat bodies, no body cavity, triploblastic animals. Many are parasites. Examples include tapeworms and liver flukes.
• Nemathelminthes (threadworms or roundworms): Small, thread-like, unsegmented bodies, triploblastic animals. Many are parasites and found in various environments. Examples include ascaris, pinworms, and filarial worms.
• Annelida (segmented worms): Body divided into segments, soft bodies, triploblastic, have a body cavity, basic organ systems. Examples include earthworms and leeches.
• Arthropoda (animals with jointed legs): Largest group, bodies are segmented, have a body cavity (haemocoel), have organ systems, which are often primitive. Examples of Arthropods Include insects, arachnids, crustaceans, etc.
• Echinodermata (spiny skinned animals): Beautiful marine animals with rough, spiny, and star-like, disc-like, or flower-like bodies. They have a true coelom, a body cavity, with a network of fluid filled canals that facilitate gas exchange, locomotion, and feeding. Move using tube feet to help in feeding and respiration. Examples include starfish, sea urchins, and brittle stars.

Vertebrates: Five Major Groups

• Pisces (fishes): Aquatic animals with gills for respiration, two chambered hearts, scales, fins for locomotion. Water-dwelling, cold-blooded. Examples include Rohu, tuna, sharks, and seahorses.
• Amphibia (amphibians): Live in both water and land. Undergo metamorphosis from aquatic larvae (tadpole) to terrestrial adult. Lungs and limbs develop; three chambered heart; cold-blooded. Examples include frogs, toads, and salamanders.
• Reptilia (reptiles): Adapted for life on dry land. Lay eggs on land. Partially divided four-chambered heart. Dry, scaly skin. Lungs for respiration. Cold-blooded. Examples include turtles, lizards, crocodiles, snakes, and chameleons.
• Aves (birds): Adapted for flight. Hollow bones for lightness, feathers, modified forelimbs (wings), four chambered heart, warm-blooded, lay hard-shelled eggs. Examples include hen, sparrow, eagle, peacock, ostrich.
• Mammalia (mammals): Live on land, majority are terrestrial (some are aquatic). Warm-blooded. Give birth to live young. Mammary glands nourish young ones. Have four-chambered hearts and lungs. Examples include rats, kangaroos, lions, deer, humans.