1. Introduction to Animals

2. Characteristics All multicellular & eukaryotic
Cells lack cell walls and come in a variety of shapes.
Ingestive heterotrophs (take in food and internally digest it).

3. Characteristics cont’d
Have some type of skeletal support
Exoskeletons found in arthropods cover the outside of the body but limit size.
Endoskeletons found in all vertebrates are found inside the body and are made of cartilage and/or bone.

4. Characteristics Cont’d
Worms have fluid-filled internal cavities giving them skeletal support.
Sponges have the simplest skeleton.
May be sessile (attached and non-moving) or motile (able to move around).

5. Characteristics Cont’d
Muscular tissue provides energy for movement.
Reproduces sexually.
Shows levels of organization including cell, tissue, organ, and system.

6. Characteristics Cont’d
Most show division of labor among cells.
Cells are specialized for particular functions.
Cell junctions hold individual cells in a tissue together. They link neighboring cells.
Most vertebrates have a backbone or spine made of repeating bones called vertebrae that protect the spinal cord.
Some show cephalization (have a head with sensory organs concentrated there).

7. Invertebrate Groups Simplest animals
Contains the greatest number of animal species
Most found in water
Do not have a backbone
Includes sponges, cnidarians, flatworms, roundworms, annelids (segmented worms), mollusks, arthropods, and echinoderms.

8. Vertebrate Groups More complex animals Most have a backbone
Includes fish, amphibians, reptiles, birds, and mammals.

9. Body Areas Dorsal is the back or upper surface
Ventral is the belly or lower surface
Anterior head or front end
Posterior is the tail or hind end opposite the head
Oral surface in echinoderms is where the mouth is located (underside)
Aboral surface in echinoderms is the surface opposite the mouth

10. Body Areas: (Most Animals)
DORSAL
POSTERIOR
ANTERIOR
VENTRAL
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11. Symmetry
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12. Body Symmetry
Also called asymmetrical

13. Body Symmetry
Symmetry is the arrangement of body parts around a central plane or axis
Asymmetry occurs when the body can’t be divided into similar sections (sponges)
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14. Body Symmetry
Radial symmetry occurs when body parts are arranged around a central point like spokes on a wheel (echinoderms)
Most animals with radial symmetry are sessile (attached) or sedentary (move very little)
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16. Body Symmetry
Bilateral symmetry occurs when animals can be divided into equal halves along a single plane
Organisms will have right and left sides that are mirror images of each other
More complex type of symmetry
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17. Body Symmetry Animals with bilateral symmetry are usually motile
Animals have an anterior and posterior ends
Show cephalization (concentration of sensory organs on the head or anterior end)
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19. Segmentation
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20. Segmentation
Occurs whenever animal bodies are divided into repeating units or segments
Found in more complex animals
Earthworms show external segmentation, while humans show internal segmentation (vertebrae of the backbone)
Segments may be fused together such as cephalothorax covering chest & head of a crayfish

21. Segmentation
cephalothorax
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22. Tissue Development
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23. Tissue Development Cont’d
All animals reproduce sexually, but some also reproduce asexually (sponges bud & flatworms fragment)
Zygote is the fertilized egg all animals form from
Zygote undergoes rapid cell divisions known as cleavage to become hollow ball of cells called blastula
Blastocoel is the central cavity of the blastula

24. Tissue Development Cont’d
Blastula folds inward at one point to form an opening & two cell or germ layers; process called gastrulation
New cup-shaped structure with 2 cell layers is called the gastrula
Archenteron is the deep cavity of the gastrula that forms the primitive gut
Blastula

25. Tissue Development Cont’d
Inner germ layer called endoderm & outer germ layer called ectoderm
Opening may become the mouth or the anus
Protostomes (mollusks, arthropods, & annelids) develop mouth from blastopore, while deuterostomes (echinoderms & vertebrates) develop an anus from blastopore

26. Tissue Dev. Cont’d
Some animals form a third germ layer in the middle called mesoderm
Cells differentiation during development changing their shapes to fit their function ( neurons or nerve cells become long to conduct messages)

27. Germ Layers Form tissues, organs, & systems NOT present in sponges
Ectoderm (outer) – forms skin, nerves, sense organs
Endoderm (inner) – forms liver and lungs
Mesoderm (middle) – forms muscles & other systems
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28. Body Layers Sponges have NO tissues or organs, only specialized cells
Cnidarians like jellyfish & coral have only two body layers & one body opening (mouth/anus) into gastrovascular cavity
Cnidarians have outer epidermis & inner gastrodermis with jelly-like mesoglea between the layers
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29. Body Layers
All worms, mollusks, arthropods, echinoderms, and vertebrates have three cell layers
Ectoderm
Endoderm
Mesoderm
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30. Embryonic Cleavage
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31. Cleavage Cleavage – rapid mitosis (cell division) of zygote
Radial Cleavage – cells divide parallel or perpendicular to axis to each other
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32. Cleavage
Spiral Cleavage – cellular divisions occur diagonally, in a twisting pattern
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34. Stages of Development
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35. Larval Forms
Animals with Indirect development go through immature (larval) forms
Larva does NOT resemble adult
Cnidarian (jellyfish, coral, & sea anemone) larva called Planula
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36. Larval Forms Mollusk (squid & octopus) larva called trochophore
Echinoderm (starfish) larva is called Dipleurula
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37. Metamorphosis Usually found in arthropods
May be complete or incomplete
Incomplete Metamorphosis:
egg nymph adult
Complete Metamorphosis:
egg larva pupa adult
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38. Metamorphosis
COMPLETE
INCOMPLETE
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39. Body Cavities
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40. Coelom - Body Cavity Internal body cavity fully lined with mesoderm
Body organs suspended in this cavity
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41. Coelom - Body Cavity
Acoelomate animals have solid bodies filled with cells
Acoelomate animals include sponges, cnidarians, & flatworms
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42. Coelom - Body Cavity
Pseudocoelomate animals (roundworms) have a functional body cavity NOT fully lined with mesoderm
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43. Animal Systems
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44. Support Systems Spongin & spicules (sponges) Limestone cases (corals)
Exoskeletons of Chitin (arthropods)
Limits size
Must be shed or molted to grow
Animal vulnerable to predators during molting
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45. Support Systems
Hydrostatic skeleton – fluid filled body cavity (worms)
Inner Calcium plates or Test (echinoderms)
Bone and/or cartilage endoskeleton (vertebrates)
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46. Exoskeletons Must Be Molted

47. Endoskeletons Grow with the Animal

48. Digestive Systems All animals are ingestive heterotrophs
Choanocytes (specialized cells) capture & digest food for sponges
Gastrovascular cavity with one opening in cnidarians and flatworms for food to enter & leave; called two-way digestive system
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49. Gastrovascular Cavity with Mouth Only (Cnidarians)

50. Two-Way Digestion
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51. Digestive Systems
Animals with a one-way digestive system have a mouth and an anus
Food enters the mouth, continues in one direction through the digestive tract, and wastes leave through the anus
Includes annelids, arthropods, & vertebrates
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52. One-Way Digestion
Mouth
anus
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53. Circulatory Systems Transports oxygen & nutrients to cells
Carries away wastes & carbon dioxide from cells
Sponges, cnidarians, & flatworms do NOT have circulatory systems
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54. Circulatory Systems
In closed circulation, blood remains inside blood vessels until it reaches cells (annelids & vertebrates)
In open circulation, blood is pumped out of blood vessels to bathe tissues in the body cavity or hemocoel (arthropods & mollusks)
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55. Open Circulation Closed Circulation
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56. Respiratory System Taking in O2 & releasing CO2
Gases can diffuse across moist surfaces (earthworms)
Gills filter O2 from water (aquatic animals)
Lungs take O2 from air (terrestrial animals)
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57. Skin breather
Gills
Lungs
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58. Nervous System Coordinates the activities of the animal’s body
Neurons – nerve cells that transmit electrochemical signals
Nerve net - network of neurons, very little coordination
Ganglion – clusters of neurons; may serve as a simple brain
Brain – control center at anterior end
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60. Excretory System
Excretion is the removal of nitrogen wastes from the body
Diffusion is used by simple aquatic animals
Flame cells remove wastes in flatworms
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61. Excretory System
Coiled tubules called nephridia remove nitrogen wastes in arthropods
Terrestrial animals remove wastes with Kidneys
May be paired (most vertebrates)
May be single as in birds
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63. Reproductive System
Reproduction is the process by which organisms make more of their own kind
All animals reproduce by sexual reproduction (produce eggs and sperm)
Some animals also use asexual reproduction creating identical offspring
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64. Types of Animal Asexual Reproduction
Regeneration or Fragmentation is the breaking off of pieces and the re- growth of a new organism
Found in simple animals like Sponges and Flatworms
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65. Budding occurs in hydra whenever a growth on the parent is released
Creates a clone
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66. Komodo dragon is an example
Parthenogenesis – females produce eggs that develop unfertilized into female organisms
Komodo dragon is an example
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67. Most hermaphrodites do NOT fertilize their own eggs
Hermaphrodite are animals like earthworms that produce BOTH eggs and sperm
Most hermaphrodites do NOT fertilize their own eggs
Mate to exchange sperm
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68. Fertilization
External – sperm and eggs are released into water where they are fertilized
Internal – sperm and egg are fertilized inside the female animal’s body
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