The Animal Kingdom

Define phylogenic tree-explain why scientists use them.

~General Characteristics ~ Multicellular-made up of more than one type of cell Eukaryotic Heterotrophs

~General Characteristics ~ Invertebrate- Does NOT possess or develop a vertebral column (backbone), derived from the notochord

Vertebrate- Developes a vertebral column (backbone) from the notochord

– Hydrostatic Skeleton: Water supported skeleton – Exoskeleton: hard outer covering made of chitin – Endoskeleton: Made of bone or cartilage, inside of the body

Body Cavity- fluid-filled space located between an animal’s outer covering (epidermis), and the outer lining of the gut cavity, where internal organs develop

1. Acoelomates – animals have 3 tissue layers with a digestive tract but no body cavities.

2. Pseudocoelomates – animals with a fluid- filled body cavity between the endoderm & mesoderm

3. Coelomates – animals with a body cavity completely surrounded by mesoderm. – They have space for internal organs to attach

~ Characteristics ~ Most animals develop from a zygote or “fertilized egg.” The zygote goes through a series of cellular divisions to form a Blastula – a hollow ball of cells.

~ Developmental Characteristics ~ These cells will form into 3 tissue layers by a process called gastrulation: – Ectoderm, a layer of cells on the outer surface of the gastrula – Endoderm, a layer of cells lining the inner surface of the gastrula – Mesoderm, made up of two layers of cells lying between the ectoderm and endoderm – middle layer

~General Characteristics ~ Bilateral Symmetry Radial Symmetry Asymmetrical Symmetry

Open Circulatory System the blood flows from the heart through open-ended vessels into sinuses where it bathes the tissues inside the cavity. This is how gas exchange occurs.

Closed Circulatory System The blood of a closed system always flows inside vessels and is pumped around the entire body for gas and nutrient exchange.