Animal Diversity

1
Chapter 18

• Animal Diversity

2
Animal Kingdom

• Animals
• Multicellular
• Heterotrophic
• Nutrients by ingestion
• Cells lack walls
• Most have muscles and nerves
• Diploid with sexual reproduction
• Similar development (controlled by Hox genes)

3
Invertebrates

• Sponges
• Stationary
• Radial symmetry
• Two layers of cells
• No tissues
• Specialized cells

4

• Outer layer
• Choanocytes
• Flagellated
• Sweep water into sponge cavity
• Trap bacteria
• Amoebocytes
• Collect and digest bacteria
• Take nutrients to other cells

5

• Cnidnarians (Jellyfish)
• Radial symmetry
• Two forms
• Polyp
• Medussa
• Tentacles
• Push food into gastrovascular cavity
• Incomplete digestive tract
• Cnidnocytes
• Capture prey

6

• Flatworms
• Bilateral symmetry
• Front, back
• Top, botttom
• Incomplete digestive tract
• Solid bodies
• Nervous tissue
• Sensory areas
• Light, chemical
• Muscles

7

• Free living
• Planarians
• Flukes
• Parasitic
• Schistosomiasis
• Two hosts
• Sexual and asexual reproduction
• Humans and snails
• Larvae

8

• Tapeworms
• Parasitic
• Absorb nutrients
• Live in animal intestines
• Scolex (head with suckers)
• Reproductive units
• Both male and female
• Prey ingest eggs, predator ingests larvae in prey

9
Body cavities

• Body cavity
• Space between digestive tract and body wall
• Filled with fluid
• Three levels in animals
• Three kinds of tissue layers
• Endoderm inner layer
• Mesoderm middle
• Ectoderm outer tissues

10
Body Cavities

• No body cavity
• Flatworms
• Solid body
• Pseudocoelum
• Body cavity not lined with mesoderm
• Coelum
• Body cavity completely lined with mesoderm

11
Advantages

• Aids in movement
• Flexible
• Hydrostatic skeleton in earthworms
• Cushions organs
• Internal organs grow and move independenly of
  outer wall
• Circulate nutrients and aid in waste elimination

12
Roundworms /Nematodes

• Outer cuticle (exoskeleton)
• Complete digestive system
• One way flow
• Specialized regions
• Digestion
• Absorption
• Longitudinal muscles
• Thrashing movement
• Pseudocoelum

13

• Caenorhabditis elegans
• Model for developmental studies
• Parasites of plants and animals
• Humans parasites
• Hookworms, pinworms, Ascaris, Trichinella
• Dog heartworms

14
Mollusks

• Basic body plan
• Foot, mantle, visceral mass
• Many have shells
• Radula to scrape food
• True coelom
• Separate sexes

15
Three classes

• Gastropods
• Snails and slugs
• Some live on land
• Bivalves
• Clams, oysters, mussels, scallops
• Cephalopods
• Squid and octopus
• Foot modified as tentacles
• Primitive brain

16
Segmentation

• Subdivision of body lengthwise
• Greater flexibility and mobility
• Systems may be repeated in each segment
• Annelids
• Earthworms
• Polychaetes
• Leeches

17
Arthropods

• Largest group of animals
• Jointed appendages for walking, swimming,
  feeding, sensory reception, defense
• Exoskeleton protein and chitin
• Varies in thickness
• Shed to grow
• Segments grouped to form head, thorax, abdomen

18
Major groups

• Horseshoe crab not a crab
• Arachnids
• Scorpions, spiders, mites
• Pincers, eight legs
• Crustaceans
• Lobsters, crayfish, shrimp,barnacles
• Aquatic
• Millipedes and centipedes
• Insects

19
Insects

• Three part body
• Head
• Sensory antennae, eyes, mouth parts
• thorax
• 3 pairs legs, wings (from cuticle)
• Abdomen
• Metamorphosis
• Complete larval forms different from adults
• Incomplete larvae look like adults

20
Echinoderms

• Sea stars, sand dollars, sea urchins
• Radially symmetrical
• Internal skeleton
• Water vascular system
• Development similar to chordates

21
Chordates

• Similar features
• Dorsal, hollow nerve tube
• Notochord
• Pharyngeal slits
• Muscular post anal tail
• Vertebrates
• Skull and backbone (vertebrae)
• Enclose brain and nerve cord
• Legs or fins
• Hinged jaw

22
Major groups

• Fish
• Amphibians
• Reptiles
• Birds
• Mammals

23
Fish

• Cartilaginous fish
• Sharks, rays, skates
• Strong senses
• Bony fish
• Hard skeleton
• Operculum (gill covering)
• Swim bladder

24
Amphibians

• Mixture of land and water adaptations
• Tied to water for reproduction
• Lay eggs in water
• Larval forms live in water
• Frogs, toads, and salamanders

25
Reptiles

• Lizards, snakes, turtles,crocodiles, alligators
• Skin covered with keratin scales
• Eggs covered with shells to prevent dehydration
  (Amniotic egg)
• Ectothermic control internal temperature by
  behavioral adaptations

26
Birds

• Amniotic eggs
• Adaptations for flight
• Feathers
• Honeycombed bone structure
• Lack some structures (teeth)
• High metabolic rate
• Lungs and circulatory system for energy
• Wing shape specialized for type of flight

27
Mammals

• Characteristics
• Hair
• Mammary glands
• Three groups
• Monotremes
• Marsupials
• Eutherians or placentals

28

• Monotremes
• Egg layers
• Platypus
• Secrete milk for young

• Marsupials
• Brief gestation
• Young live in pouch attached to mothers nipples
• Kangaroo, opposum

29
Eutherians

• Placenta holds embryo to amniotic sac
• Rodents small plant eaters
• Bats flying mammals
• Moles small insect eating burrowers
• Carnivores - predators
• Primates large brain, opposable thumb
• Hoofed mammals

30

• Marine mammals
• Lagamorphs - rabbits
• Pinnipeds marine carnivores
• Toothless insect eaters
• Hoofed animals with 1or 3 toes
• Proboscidea -elephants

31
(No Transcript)