Animal Diversity

Kingdom Animalia

A biological kingdom encompassing all animals on Earth.

Vertebrates

Animals with a backbone.

Invertebrates

Animals without a backbone.

Chordata

A phylum to which vertebrates belong.

Cephalization

Evolutionary trend concentrating nervous tissue, mouth, and sense organs towards the front end of an animal.

Symmetry

Balance or agreement in dimensions of an organism.

Hydrostatic Skeleton

A skeleton formed by a fluid-filled compartment within the body.

Exoskeleton

An external skeleton consisting of a hard encasement on the surface of an organism.

Endoskeleton

A skeleton consisting of hard, mineralized structures located within the soft tissue of organisms.

Homologous Structures

Anatomical features sharing a common evolutionary origin, indicating descent from a common ancestor.

Analogous Structures

Similar functions performed by different structures that have evolved independently due to similar environmental pressures, not derived from a common ancestor.

Hydrostatic Skeleton

A skeleton formed by a fluid-filled compartment within the body, providing support and movement through hydrostatic pressure.

Exoskeleton

An external hard encasement on the surface of an organism providing defense, support, and movement through muscle contractions.

Endoskeleton

A skeleton consisting of hard mineralized structures within the soft tissue of organisms, offering mechanical support, protection, and movement.

Immovable (Fixed) Joints

Fibrous joints found in the skull bones that are strong but do not allow movement.

Slightly Movable Joints

Cartilaginous joints allowing slight, restricted movement with cartilage reducing friction between joints.

Freely Movable (Synovial) Joints

Structurally classified as synovial joints, allowing various movements with a joint cavity filled with synovial fluid.

Synovial Joints

Four main types include ball and socket, hinge, pivot, and gliding joints, enabling different ranges of movement.

Skeletal System Functions

Protects internal organs, produces blood cells, facilitates movement, stores and releases minerals and fat, and provides mechanical support to the body.