REVIEW

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• REVIEW
• Compare/contrast mollusks
• What are the 3 Classes

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InvertebratesArthropods
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Evolution of Arthropods

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• Phylum Arthropoda- jointed legs
• Germ Layers 3
• Body Symmetry/shape bilateral
• Segmentation yes
• a. Jointed appendages allows for
  varied movement(arms,legs,tail)
• b. head, thorax, abdomen or cephalothorax
  fused head thorax
• Coelom True Coelom
• Nervous cephalization present sharp senses
  antennae, compound and simple eyes, use of
  pheromones

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Other arthropod characteristics

• Skeleton Exoskeletons
• hard (protection), outer covering that must be
  molted (shed)
• Digestion 2 body openings complex variety of
  jaws(Mandibles) adapted for type of food eaten
• Excretion malpighian tubules-excrete liquid
  wastes
• Circulation Open 1 or more hearts

Malpighian tubules (purple)
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Other arthropod characteristics

• Respiration 1. Crustaceans Gills
• 2. Arachnids-Book Lungs
• 3. Insects- Tracheal tubes-
  holes-spiracles
• Reproduction sexual
• internal fertilization if terrestrial
• external fertilization if aquatic
• some are hermaphrodites most separate sexes
• Some Parthenogenesis-development from
  unfertilized eggs

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Importance of Arthropods

• Harmful (bad)
• Destroy crops
• Carry disease
• Destroy Wooden structures (termites)
• Bite/sting animals and people

• Beneficial (good)
• food source
• Pollinate flowers/crops
• Produce raw material (silk honey)
• Help control insect population (spiders)
• Used in medicines
• Decomposers

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Which animals are arthropods?

• Crustaceans
• Arachnids
• Insects.
• Centipedes
• Millipedes

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Crustaceans

• Mostly aquatic(gills), usually found on floor
• 2 body sections cephalothorax abdomen
• Sexual reproduction separate sexes
• Two pairs of antennae
• Two compound eyes usually on stalks
• Pill bugs only full time terrestrial crustacean

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Crustaceans

• Varied appendages
• 1. chelipeds pincers 1pair
• 2. walking legs- 4 pair
• 3. swimmerets 5 pair underside of tail, used
  for swimming reproduction(if lst 2 pairs are
  larger-male)

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The Anatomy of a Crayfish
Section 28-2
Abdomen
Cephalothorax
Walking legs
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Arachnids.

• Two body segments cephalothorax and abdomen
• 6 pairs of appendages
• 1. chelicerae 1 pair near mouth, modified as
  pincers or fangs
• 2. Pedipalps 1 pair near mouth, adapted for
  handling food and sensing
• 3. 4 pairs of walking legs

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Spiders
Garden Spiders

• NOT all are poisonous paralyze prey
• Two may be fatal to humans in US brown recluse,
  black widow
• 6-8 simple eyes
• Book lungs
• No mandibles-jaws must liquify food before
  eating
• No antennae
• All produce silk in glands-Spinnerets not all
  form webs
• Reproduction sexual female larger she eats
  male

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Anatomy of a Spider
Section 28-2
Cephalothorax
Abdomen
Book Lung
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Class Insecta

• Entomologist person who studies insects
• General Characteristics of Insects
• 1. Largest group of Arthropods/most diverse
  group of animals
• 2. Three body regions head, thorax, abdomen
• 3. Three pairs of legs (6 total) 2 sets of
  wings(only inverts that can fly)
• 4. One pair of antennae
• - sense vibration food

Insects (73)
antennae
1 2 3
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• Eyes
• a) at least one pair of compound eyes
• b) usually 2 compound eyes 3 simple eyes

Simple eyes
Compound eyes
mandibles
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1. Sensory hairs cover antennae exoskeleton
2. Tracheal tubes spiracles-breathing
3. Tympanum hearing, ventral side near thorax

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2
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Grasshopper
Ventral View
Tracheal tubes
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Two types of Insect Life CyclesMETAMORPHOSIS
Section 28-3
Adult
Eggs
Adult
Eggs
IncompleteMetamorphosis
CompleteMetamorphosis
Larva
Adult
Nymph
Nymph
Immature
Larva
Nymph
Adult
Pupa
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• Specialized Mouthparts Evolution- FYI
• Piercing mouthparts feed by inserting tube-like
  mouth into food usually to suck blood
• Ex mosquito
• Sucking mouthparts feed by
• unrolling tube-like mouth to reach
• nectar inside of flowers
• Ex butterfly

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• Sponging mouthparts feed by lapping up food
  after secreting enzymes to digest food
• Ex flies
• Chewing mouthparts feed by biting and chewing
  on food
• Ex Beetles

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Millipedes/centipedes.

• Centipedes (means 100 legs, but can vary). 1
  pr./segment
• a. carnivores
• b. bite with pincers, inject poison
• c. live under rocks, dead leaves
• d. flattened bodies which may have bright
  colors
• 2. Millipedes (means 1000 legs, but can vary). 2
  pr./segment
• a. eat plants, dead matter (saprophytic)
• b. dont bite, but can spray fluid from stink
  glands
• c. live on damp forest floor
• d. rounded bodies which are usually dull in
  color