Introduction to Kingdom Animalia. Defining Animals 1. Animals are multicellular, heterotrophic eukaryotes. 2. Animals generally store their carbohydrate reserves as glycogen
1. Animals are multicellular, heterotrophic eukaryotes.
2. Animals generally store their carbohydrate reserves as glycogen
3. Animal cells possess a number of unique cellular structures, e.g., gap junctions - intracellular junctions that allow the passage of materials between cells
4. Animals possess special tissues that are responsible for impulse conduction (nervous tissue) and movement (muscle tissue).
5. Most animals reproduce sexually, with the diploid stage dominating the life cycle
1. The Parazoa-Eumetazoa Split
Two basic kinds of animals evolved early in animal evolution.
A.Parazoa("beside the animal")- animals that lack true tissues. e.g., Sponges
B.Eumetazoa - animals with well defined tissue layers,
e.g., essentially all other animals.
4. The Protostome-Deuterstome Split
Coelomates, can be divided into 2 distinct groups: protostomesand deuterostomes.
They are distinguished based upon fundamental differences in early development, including cleavage, fate of the blastopore, and coelom formation
Protostomes - Spiral, determinate cleavage
Deuterostomes - Radial, indeterminate cleavage