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Introduction to Animals

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1 Introduction to Animals
Bio II Chapter 32 Introduction to Animals

2 Animals that have a backbone Animals that do not have a backbone
Animals: multicellular, heterotrophic (eat for energy) organisms that lack a cell wall. Vertebrate invertebrate Animals that have a backbone Animals that do not have a backbone Account for more than 95% of all animal species

3 Characteristics of animals
Multicellular Organization Heterotrophy Sexual Reproduction and Development Movement

4 1. Multicellular Organization
all bodies are multicellular Some have larger # than others, 50 – 100 trillion cells Cells do not lead independent lives Each cell depends upon the presence and functioning of other cells Causes a “division of labor” among cells: each has a job

5 SPECIALIZATION: adaptation of a cell for a particular function
Each cell has a “job” to do, from digesting food, to removing waste, to reproduction. Cell: smallest unit that can perform life processes

6 Specialization Heirarchy
cells Tissue: group of cells that perform a particular function Organ: group of tissues that perform a particular function System: group of organs that perform a particular function

7 2. Heterotrophy Heterotrophy: to obtain complex organic molecules from other sources Animals accomplish this through INGESTION INGESTION: take in organic material or food

8 3. Sexual Reproduction & Development
Asexual Sexual

9 SEXUAL REPRODUCTION: 2 haploid gametes merge zygote
Zygote: diploid cell that results from the fusion of the gametes The zygote undergoes mitotic cell division (Development) The big mass of cells undergoes DIFFERENTIATION: cells become specialized and therefore differentiate from each other.

10 MOVEMENT comes from their interrelationship
Nervous tissue Muscle tissue MOVEMENT comes from their interrelationship

Taxonomy: the science of describing, naming, and classifying organisms Scientists use a “phylogenic diagram” page 653 to relate similar organisms

12 CLASSIFICATIONS Domain Kingdom Phylum Class Order Family Genus Species

13 Domain: Eukarya, Bacteria, Archaea
Kingdom Animalia, Plantae, Eubacteria, Archaebacteria, Protista, & Fungi Family Phylum Species Genus Order Class

14 The 1st Animals Probably arose from the sea Evolved from protists
First to be multicellular Had flagella See chart on page This phylogenic diagram is a HYPOTHESIS for the relationship in the animal kingdom . Far right: Chordata

15 Chordates Chordate: animals with a notochord (a firm, flexible rod of tissue located in the dorsal part of the body. At some stage of development, all chordates have: Notochord: Dorsal Nerve Cord: a hollow tube above the notochord Pharyngeal pouches: small “outpockets” of the anterior digestive tract.

16 Body Structure of Invertebrates
Those that lack true tissues and an organized body shape Those that have very organized tissues and a consistent body shape

17 4 elements of body structure
Patterns of Symmetry Germ Layers Body Cavities Body Structure & Relatedness

18 1. Patterns of Symmetry p655 Symmetry: body arrangement in which parts that lie on opposite sides of an axis are identical Asymmetrical Radial Bilateral

19 Asymmetrical Asymmetry: do not display any symmetry
Animals have the simplest body plan of all Example: sponges

20 Radial Symmetry Radial Symmetry: a body plan in which the parts are organized in a circle around an axis Animals that have a top and bottom side They do not have a front, back, right or left end. Example: cnidarians (sea anemone) page 655

21 Bilateral Symmetry Bilateral Symmetry: having similar halves on either side of a central plane Cephalization: concentration of brain structures in anterior of animal Example: squirrel Dorsal ( back side) Ventral ( abdomen side) Anterior (toward the head) Posterior (toward the tail)

22 2. Germ Layers Tissue layers in the embryos of all animals except sponges. (Sponges have no true tissue.) Can be 2 or 3 layers, depending upon the organisms. Every organ and tissue arises from a germ layer.

23 3. Body Cavities Body-cavity: a fluid-filled space that forms between the digestive tract and the outer wall of the body during development Not all invertebrates have a body cavity Aid in movement by providing a firm, fluid structure against which muscles can contract Allows for movement of the external body, compared to the internal body Acts as a reservoir and medium of transport for nutrients and wastes

24 4. Body Structure & Relatedness
Similarity in body plans allows for classification Predicting the past relationships

25 Invertebrate 7 main characteristics Symmetry Support of the body
Segmentation Support of the body Respiratory & Circulatory systems Digestive & Excretory systems Nervous system Reproduction & Development

26 1. Invertebrate Symmetry
Radial Symmetry Bilateral Symmetry Example: jellyfish Allows animal to receive stimuli from all directions Allows for cephalization Most invertebrates have this type of symmetry Examples range from slugs to squids

27 2. Invertebrate Segmentation
Segmentation: body composed of a series of repeating similar units Simplest form seen in earthworm More complex form seen in crayfish; fusion of segments to create a head and chest region

28 3. Invertebrate Support of the Body
Very diverse means of support “natural sponge” in stores: that is the dried skeleton Roundworms: pressure of fluid-filled body cavity EXOSKELETON: rigid outer covering that protects the soft tissues of many animals Limits the size of the animal May impede the movement Does not grow; must be shed as animal grows Examples: crayfish

29 4. Invertebrate Respiratory & Circulatory Systems
Produce CO2: therefore must have gas exchange Gas exchange: occurs best in moist environment Some invertebrates: it occurs across the body covering. Others: have GILLS: organs that consist of blood vessels that exchange gas in water 2 types of circulatory systems: OPEN: fluid pumped thru vessels and into body cavity and back to heart Ex.: some mollusks & arthrodpods CLOSED: Heart pumps blood thru vessels and into a simple loop back to the heart Ex.: annelids

30 5. Invertebrate Digestive & Excretory Systems
Simpler animals: occurs within individual cells More complex animals: has a digestive tract (gut) in which nutrients are absorbed Simpler animals: waste is excreted as NH3 (ammonia) More complex animals: NH3 is filtered and converted to less toxic substances; water is reabsorbed by body

31 6. Invertebrate Nervous System
Sponges (simpler animals) Mollusks (more complex) Have no neurons to loosely connected neurons Very diverse system Can contract body in response to stimuli Very complex animals can exhibit decision-making behavior (like the octopus)

32 7. Invertebrate Reproduction & Development
Both sexual & asexual Some are “hermaphrodites”: both sexes ex. Earthworm Produces both male & female gametes Indirect development: has an intermediate stage called a larva stage. Larva: immature, free-living form of adult Direct development: young animal born with same appearance and way of life it will have as an adult No larva stage

33 Larva has an intermediate larval stage.
Zygote Young Larva Older Larva Pupa Adult Indirect Development Example: Beetle Development Larva has an intermediate larval stage. Larva is an immature for that exhibits physical traits that are different from those of the adult.

Have a backbone Includes fishes, amphibians, reptiles, birds & mammals All except fishes spend part or all of their life on land In order to adapt to life on land: Support of the body Conservation of water

35 1. Vertebrate Segmentation & Support of the Body
Yes, they are segmented! Ex. Ribs & vertebrae As terrestrial vertebrate evolved from aquatic vertebrates, their limbs and muscles evolved to give greater support & mobility. Humans: BIPEDAL Head is positioned directly over the body

36 2. Vertebrate Body Coverings
INTEGUMENT: outer covering Fish and amphibians adapted to moist environments Terrestrial adapted to dry conditions All bodies are made of water-filled cells. Outer covering is watertight! In some vertebrates such as amphibians, skin serves as a respiratory organ. In some vertebrates such as reptile, skin serves as protection. In some vertebrates such as birds, feathers serve as insulation.

37 3. Vertebrate Respiratory & Circulatory Systems
Aquatic Vertebrates: gases exchange in gills Terrestrial Vertebrates: LUNGS: organs for gas exchange CLOSED circ. System with a MULTICHAMBERED HEART Separates oxygenated and deoxygenated blood Improves efficiency

38 4. Vertebrate Digestive & Excretory Systems
Digestion occurs in the GUT: runs from mouth to anus In vertberates, the gut is long and folded to increase surface area for nutrient absorption Human tract: 23 feet long Produce toxic ammonia (NH3) Must expel waste w/o losing water! Kidneys filter the waste in the blood while regulating water levels in the body

39 5. Vertebrate Nervous System
Highly organized brains Fish: mainly used to process sensory information. Limited amount is used to decision making Dogs and such display complex and flexible behavior. Much of brain is given to decision making. Brain is large in respect to body size.

40 6. Reproduction & Development
Fish & amphibians: eggs & sperm are released directly into the water where fertilization takes place Reptiles, birds & mammals: egg & sperm unite in female body Zygote nourished by egg yolk until hatch. Most of development occurs OUTSIDE of female’s body. Amphibians & fish: indirect development All others: direct dev.

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