Overview of Animal Kingdom and Major Phyla

Kingdom Animalia

Multicellular, eukaryotic, heterotrophic organisms.

Vertebrates

Animals with a nerve cord and vertebral column.

Invertebrates

Animals lacking a vertebral column; >95% of animals.

Tissues

Groups of cells performing a specific function.

Symmetry Types

Radial, bilateral, and asymmetry classifications.

Coelom

Body cavity allowing organ suspension and movement.

Sponges

Phylum Porifera; asymmetrical, lack tissues and coelom.

Ostia

Small openings in sponges for water intake.

Choanocytes

Flagellated cells in sponges for water flow.

Osculum

Large opening in sponges for water expulsion.

Cnidarians

Radial symmetry, diploblastic organisms with nematocysts.

Mesoglea

Gelatinous layer in cnidarians between tissue layers.

Polyp

Sessile body form of cnidarians.

Medusa

Free-swimming body form of cnidarians.

Cnidocytes

Specialized cells in cnidarians containing nematocysts.

Flatworms

Phylum Platyhelminthes; bilateral, triploblastic, acoelomate.

Roundworms

Phylum Nematoda; pseudocoelomate, unsegmented, tapered.

Segmented Worms

Phylum Annelida; metameric segmentation and coelomate.

Molluscs

Phylum Mollusca; body parts include mantle and foot.

Radula

Feeding organ in molluscs for scraping food.

Arthropods

Phylum Arthropoda; segmented with jointed appendages.

Echinoderms

Phylum Echinodermata; pentameral symmetry and water vascular system.

Acorn Worms

Phylum Hemichordata; proboscis for feeding.

Chordates

Phylum Chordata; notochord and nerve cord present.

Actinopterygii

Largest vertebrate group; ray-finned bony fishes.

Chondrichthyes

Cartilaginous fish; includes sharks and rays.

Countercurrent System

Maximizes oxygen uptake in fish gills.

Myomeres

Muscle blocks in fish for swimming.

Hermaphrodites

Organisms producing both eggs and sperm.