Introduction to Animals

1. Introduction to Animals

2. Section 1: Nature of Animals • Vertebrate vs. Invertevrate • Vertebrate – has vertebrae or backbone surrounding nerve cord (spinal cord) • Invertebrate – no backbone surrounding nerve cord; 95% of animal species!!!

3. What is an animal? • Multicellular – each cell depends on the functions of all other cells • Specialization – a cell has developed to perform one specific function; a division of labor among the cells • Cell Junctions – connections between cells that hold them together to make a tissue • Review: Tissue – group of specialized cells working on one function together

5. Heterotroph – animals must obtain organic molecules (a.k.a. food) through ingestion. • Sexual Reproduction & Development • The 1st cell is a fertilized egg – diploid zygote • Differentiation – zygote divides to produce more cells, which grow & “learn” the function(s) they will be responsible for. ***Differentiation is the process that results in Specialization!!

7. Movement • Animals have muscle and nerve tissue (or at least cells). • Neurons (nerve cells) use electrical signals to trigger muscle movements.

8. Origin & Classification of Animals • Flagellated, Colonial Protist gave rise to early invertebrates. • An invertebrate gave rise to vertebrates

9. Section 2: Animal Bodies • Symmetry – describes organization of an animal’s body, if parts are arranged in mirror images of one another. • Asymmetry – body shows no symmetry • Ex: sponges, corals

10. Radial Symmetry – body has 2 or more planes of symmetry, body is arranged in a circular fashion • Ex: star fish, anemones, sand dollars

11. Bilateral Symmetry – body has only one plant of symmetry • Ex: fish, mammals, birds (all vertebrates!)

12. Anatomical Positions – term that describes areas of the body • Anterior – towards the head • Posterior – towards the tail • Dorsal – towards the upper part or back of a standing animal • Ventral – towards the lower part or belly of the standing animal

13. Medial – towards the midline plane that separates right and left sides of a body • Inferior – below or under a body part • Superior – above or over a body part • Caudal – toward the back or tail • Cranial – toward the front or head

14. Body Tissues & Cavities • Germ Layers – tissue types found in embryos • Sponges have none • Cnidarians & Ctenophores have 2 germ layers (anemones and jellies) • All other animals have 3 germ layers • Are mostly bilaterally symmetrical • Show Cephalization – concentration of sensory organs toward the anterior end (in the head)

15. Body Cavities – fluid-filled space between digestive tract and outer wall of the body

16. Animal Phyla • Ten Invertebrate Phyla • Very diverse in symmetry & body organization • Ex: sponges, insects, starfish

18. One Vertebrate Phylum (Chordata) – all animals have the following structures at one point in life, but many lose them as they mature • Notochord – firm, flexible rod of tissue • Dorsal Nerve Chord – located just above the notochord; gives rise to spinal cord • Pharyngeal Pouches– our pockets of digestive tract at anterior end • Postanal Tail – muscles near posterior end

19. Section 3: Invertebrates vs. Vertebrates • Invertebrates – over 95% of animals • Symmetry – radial or bilateral • Sponges are asymmetrical • Bilateral allows for cephalization • Segmentation • Some invertebrates are segmented, the body is made of repeating units (earthworm) • Segments can be almost identical (earthworm) or very different (lobster).

20. Segmentaion

21. Body Support – what holds the body up • Simple skeletons (sponges) • Fluids inside the body cavity push out on the outer covering of the animal (roundworms) • Exoskeleton: rigid, outer covering that protects body & must be shed as the animal grows. A new exoskeleton will grow in its place (animal is very vulnerable at that time).

22. Respiratory & Circulatory Systems • Respiratory – exchange of gases (CO2 & O2) • Most invertebrates exchange gases directly through their outer covering or gills • Circulatory – moving fluid through the body to transport O2 and nutrients • Open Circ. System: blood is pumped into body cavity (no blood vessels) • Closed Circ. System: blood travels through body cavity in vessels

23. Open vs. Closed Circulatory Systems

24. Digestive & Excretory System • Digestion – break down of food to gain nutrients • Sponges: digestion occurs in each cell • Digestion can occur in a central chamber (Cnidarians) • Digestion can occur in a gut

25. Digestive & Excretory System (cont) • Excretion – release wastes from the body • Aquatic invertebrates: waste is released as ammonia • Land invert.: ammonia is converted into a less toxic substance

26. Nervous System • Using electrical impulses to control body functions • Large amounts of diversity among invertebrates!!

27. Reproduction & Development • Hermaphrodites – single animal produces both male and female gametes (earthworm) • Indirect Development – enter a larval stage, then mature into an adult • Ex: ? • Direct Development - no larval stage; at birth, animal already resembles adult form • Ex: ?

28. Vertebrates – all have bilateral symmetry!! • Body Support • Endoskeleton: internal skeleton that supports large, heavy bodies • Segmentation • All vertebrates are segmented somewhere on or in their bodies (ribs, vertebrae)

29. Body Coverings – Integument System • Aquatic Vertebrates: have moist skin which allows for gas exchange through the skin • Land vertebrates: skin is watertight • Feathers & Fur: expel water & insulate body

30. Respiratory & Circulatory Systems • Respiratory: aquatic vert. use gills; land vert. use lungs • Circulatory: closed system with a chambered heart • Digestive & Excretory Systems • Digestive: have a gut running anterior to posterior • Excretion: converts ammonia to less toxic substance; filters blood through kidneys

31. Nervous System • Brain & nervous tissue is organized into an efficient system. • Reproduction & Development • Embryos can develop in an egg outside mother’s body or inside body in a uterus. • All vertebrates undergo direct development!