Introduction to Animals 1. Heterotrophs 2. Multicellular 3. Most are Mobile 4. Most reproduce sexually/ few can asexually reproduce 5. No cell wall 6. Most (except sponges) have tissues. These are groups of cells that work together to perform a specific function. Ex: nerve tissue sends/receives signals 7. Formation of a Blastula (except sponges): a zygote that has gone through cell division until a ball of cells is formed. This ball of cells (blastula) keeps dividing until 3 distinct layers form. These layers will form into tissues and organs in the adult body. a. ectoderm: outer-layer- outer layer of skin, nervous system, sense organs b. endoderm: inner-layer- lining of digestive tract, respiratory system, urinary bladder, digestive organs such as liver, and many other glands. bladder, digestive organs such as liver, and many other glands. c. Mesoderm: Separates inner and outer layer- Most of the skeleton, muslcles, circulatory system, reproductive organs, and excretory organs. muslcles, circulatory system, reproductive organs, and excretory organs. 8. atoms, molecules, cells, tissues, organs, organ systems, organism

Body Symmetry A. Three types of symmetry: body shape 1. Asymetrical: no specific shape/irregular (Sponges, coral) (Sponges, coral) 2. Radial symmetry: body parts are arranged around a central axis, like spokes around a bicycle wheel. (Phylums Cnidarian, Echinodermata) These organisms resemble a pie where several cutting planes produce roughly identical pieces. An organism with radial symmetry exhibits no left or right sides.

3. Bilateral symmetry a. Have distinct right and left halves. A plane passing through the animal’s midline divides the animal into mirror image halves. The elaborate patterns on the wings of butterflies are one example of biological symmetry.

Dissection/Position Terms Dorsal: The back of an organism Ventral: Stomach area Medial: middle Lateral: Side Anterior: Towards the head Posterior: Towards the back end or rear end area Caudal: tail Cranial: Head

Lateral Posterior: hind end Anterior: front end Medial