Intro to Zoology

1. Intro to Zoology What is an animal?

2. Typical Characteristics: • 1) Eukaryotic –each cell has a nucleus • 2) Multicellular-Made up of many cells • Cells>Tissue>Organs>Organ Systems • 3) Heterotrophic- must eat food to get energy and nutrients- through ingestion and digestion • 4) Do not have cell walls • 5) Can Move (some are sessile, which means that they don’t move) EX: sponges and barnacles

3. Origins of animals : • Most likely evolved from colonial protists • Believed to have developed in the water

4. Phylums ***There are more than 9 phylums but these represent the most commonly seen animals. • Porifera • Cnidaria • Platyhelminthes • Nematoda • Annelida • Mollusca • Arthropoda • Chordata

5. Match the name of phylum with a picture of a member! • http://www.biologycorner.com/resources/animal_phylum_chart.gif

6. Reproduction and Development • Most animals reproduce sexually. • Some can reproduce asexually. • Fertilization occurs when a sperm penetrates an egg to form a single cell called a zygote. • This may be external (outside male and female) EX: Fish or internal ( inside the female) EX: Horse

7. Cell Division • Zygote begins dividing by mitosis to form two new cells. • Each new cell will continue to divide over and over again until a hollow ball called a blastula is formed.

8. One side of the blastula begins to fold inward, making an inner pouch. At this point, the embryo is called a gastrula.

9. Germ Layer Development • The layers that form will eventually form the tissue and organs of the animal. Most animals possess three layers of tissue (sometimes called germ layers): • 1) Ectoderm: outermost layer of cells; eventually forms the outer covering (skin) and nervous system. • 2) Mesoderm: middle layer of cells; eventually forms the skeleton, muscles, and circulatory system • 3) Endoderm: Inner layer of cells; becomes the digestive tract, internal organs, and respiratory tract

10. Body Cavities • As the layers of tissue form organs and organ systems, some organisms develop a fluid filled space that forms between the digestive tract and the outer wall of the body during development. • Not found in simple animals • May aid in movement • Fluid may act as a reservoir for nutrients and wastes, which diffuse into and out of the animal’s body

11. Types of Body Cavities • Acoelomates: 3 layers of tissue, but no body cavity is present ( Gut) • Pseudocoelomates- 3 Layers of tissue and a modified body cavity present ( not lined with mesoderm) • Coelomates- a true body cavity present (lined with mesoderm)

12. http://pulpbits.com/wp-content/uploads/2013/12/three-functions-of-a-body-cavity.jpghttp://pulpbits.com/wp-content/uploads/2013/12/three-functions-of-a-body-cavity.jpg

13. Patterns of Symmetry • Asymmetrical – an irregular shape. Some simple animals do not display symmetry (EX: Sponges) • Radial- Similar parts branch out in all directions from a central line ( like spokes on a bicycle tire) • Bilateral- two halves on either side of a central plane are similar • A. Usually exhibit cephalization –concentration of sensory structures in the anterior (head) end of the animal.

14. Bilateral Symmetry words • Terms used to describe location of certain structures and organs on an animal: • Anterior: head end • Posterior: Tail end • Dorsal: Back • Ventral: Front • http://www.dogsindepth.com/hound_dog_breeds/images/greyhound_h05.jpg

15. Segmentation • A body composed of repeating similar units • In some phyla, segments may look different and have different functions.

16. Support and Protection of Body • Hydrostatic skeleton- body is supported by the pressure of their fluid filled bodies (EX: jellyfish) • Exoskeleton- A rigid outer covering that protects the soft tissue of many animals ( includes many invertebrates such as crabs and beetles) • Endoskeleton- an internal skeleton that can support a large, heavy body

17. Vertebrate VS. Invertebrate • Most animals that exist today are classified as invertebrates; animals that lack a backbone • EX: insects, sponges, starfish, jellyfish, clams, worms, etc. • Humans are a type of chordate called a vertebrate, an animal with a backbone. • Chordata is the only phylum that contains vertebrates (although not all chordates are vertebrates)

18. Digestive System • In Sponges, digestion occurs within individual cells (intracellular) • Gastrovascular Cavity- A digestive chamber with a single opening (incomplete digestive system) Ex: jellyfish and flatworms • Digestive tract (or gut) runs from the mouth to the posterior end or anus. EX: humans, earthworms, and spiders

19. Respiratory System • Gas Exchange: the process of exchanging carbon dioxide (in the blood) with oxygen (in the environment) • Gills: Organs that are specialized for gas exchange in water • Lungs: Organs for gas exchange, which are composed of moist, membranous surfaces deep inside the animal’s body

20. Circulatory System • Moves blood or a similar fluid through the body to transport oxygen and nutrients to the cells. • Open circulatory system- blood like circulatory fluid is pumped from vessels in the body into the body cavity ( it bathes the organs) then is returned to the vessels. • Closed circulatory system- blood circulates through the body in tubular vessels.