Animal Kingdom Classification

### Animal Kingdom Classification

• Porifera are multicellular animals with cellular level of organization and flagellated choanocytes.
• Coelenterata have tentacles and cnidoblasts.
• Sponges are mostly asymmetrical.
• Radial Symmetry exists in organisms where any plane passing through the central axis divides the organism into two identical halves.
• Bilateral Symmetry exists in organisms where the body can be divided into identical left and right halves in only one plane.
• Diploblastic Animals have cells arranged in two embryonic layers: an external ectoderm and an internal endoderm.
• Triploblastic Animals have a third germinal layer, mesoderm, between the ectoderm and endoderm.
• Coelom is a body cavity lined by mesoderm.
• Cnidarians have a skeleton composed of calcium carbonate.
• Cnidarians exhibit two basic body forms: polyp and medusa.
• Polyp is a sessile and cylindrical form, like Hydra.
• Medusa is an umbrella-shaped and free-swimming form, like Aurelia.
• Alternation of Generation (Metagenesis) exists in cnidarians exhibiting both polyp and medusa forms, where polyps produce medusae asexually, and medusae form polyps sexually.
• Ctenophores are exclusively marine, radially symmetrical, diploblastic organisms.
• Ctenophores have eight external rows of ciliated comb plates for locomotion.
• Bioluminescence, the property of emitting light, is common in ctenophores.
• Platyhelminthes have a dorso-ventrally flattened body and are called flatworms.
• Platyhelminthes are bilaterally symmetrical, triploblastic, and acoelomate animals.
• Arthropoda have a jointed exoskeleton of chitin, complete digestive system, and an open circulatory system.
• Mollusca are soft-bodied animals with a calcareous shell, unsegmented body, and a mantle cavity.
• Mollusca have a file-like rasping organ called a radula for feeding.
• Echinodermata have a water vascular system and radial symmetry.
• Hemichordata have a worm-like body with a proboscis, collar, and trunk.
• Chordata have a notochord, dorsal hollow nerve cord, gill slits, and limbs or fins.
• Amphibia are cold-blooded vertebrates that live in both aquatic and terrestrial environments.
• Reptilia are mostly terrestrial animals with dry and cornified skin, epidermal scales, or scutes.
• Reptilia have a three-chambered heart (except crocodiles which have a four-chambered heart).
• Aves (birds) are characterized by feathers, beaks, and wings.
• Aves have a four-chambered heart and are warm-blooded.