Chapter 31 Arthropods

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Chapter 31 - Arthropods

• High School Biology Class

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Phylum Arthropodia (Arthropods)

• First animals with jointed appendages.
• Appendages - structures that extend from the
  arthropods body wall (legs, antennae, and
  mouthparts).
• The largest phylum with over 900,000 species,
  also some of the oldest fossils.

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Phylum Arthropodia (Arthropods)

• Have advanced segmentation of a head, thorax
  (mid-body region), and abdomen.
• Cephalothorax a head fused to the body.
• Usually have compound eyes.
• Have a hard exoskeleton made up of chitin.

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Phylum Arthropodia (Arthropods)

• Possess a tracheae and spiracles that are
  important respiratory structures.
• Have an open circulatory system.
• Malpighian tubules - excretory structures which
  eliminates metabolic (food) wastes.
• Some possess wings for flight.

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Sub-phylum Chelicerata

• Chelicerae modified mouthparts that act as
  fangs or pinchers.
• Six eyes in the cephalothorax and an abdomen
  containing spinnerets.
• All are carnivores except for mites (parasites).
• All live in terrestrial habitats.

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Class Arachnids

• None have jaws so they must liquefy their food.
• Some mites cause lyme disease (deer ticks).
• Examples
• Spider, scorpion, tick, mite

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Class Arachnids

• Note
• The only poisonous spiders in the U.S. are the
  black widow and the brown recluse.

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Sub-phylum Uniramia

• Mandibles - chewing mouthparts.
• Divided into three classes
• a) Insecta (insects)
• b) Diplopoda (millipedes)
• c) Chilopoda (centipedes)
• Most live in terrestrial habitats.

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Class Insecta (Insects)

• The largest class of organisms (with more than
  700,000 named species).
• Many of the insects have developed elaborate
  social systems called castes.
• Some insects possess the ability of flight.

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Class Insecta (Insects)

• Metamorphosis - the insect undergoes a dramatic
  physical change after several molts.

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Class Insecta (Insects)

• Examples
• Beetle, fly, mosquito, moth, butterfly, bee,
  wasp, ant, gnat, cricket, weevil, termite,
  grasshopper, dragonfly

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Class Diplopoda (Millipedes)

• Have two pairs of legs per segment.
• Have from 11 to 100 segments.
• Most are herbivores.

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Class Chilopoda (Centipedes)

• Have one pair of legs per segment.
• Have up to 173 segments.
• Most are carnivores.

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Sub-phylum Crustacea

• Nicknamed Insects of the Sea
• Most live in marine habitats, some in freshwater,
  and few in terrestrial habitats.
• Most have a nauplius larval stage.

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Sub-phylum Crustacea

• Decapod have five pairs of legs attached to the
  cephalothorax
• (i.e. lobsters, shrimp, crabs, and crayfish.)
• Cheliped the large pincher arm.
• Swimmeret appendages attached to underside and
  used in swimming.

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Sub-phylum Crustacea

• Examples
• crab, lobster, crayfish, shrimp, barnacle, water
  flea, pill bug and sow bug (terrestrial)

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Any Questions?

• No individual has any right to come into the
  world and go out of it without leaving behind him
  the distinct and legitimate reasons for having
  passed through it.
• --George Washington Carver