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

11. ORIGIN & CLASSIFICATION
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.

34. VERTEBRATE CHARACTERISTICS pg 659
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.