Arthropods!

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Arthropods!

• Biology ?

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Phylum Arthropoda

• What percentage of animals belong to the Phylum
  Arthropoda?
• 2/3, 67
• List some examples of arthropods
• Lobsters, crabs, spiders, and insects

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Phylum Arthropoda

• Like annelids, arthropods are segmented animals.
• Body segments bear jointed extensions called
  appendages such as legs and antennae.
• What does arthropod mean?
• Jointed foot

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Phylum Arthropoda

• Describe the exoskeleton of arthropods. What is
  the function of each layer of the exoskeleton?
• Outer layer repels water and helps prevent
  dessication
• Middle layer provides the primary protection
• Inner layer provides flexibility at the joints

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Phylum Arthropoda

• What is a compound eye?
• An eye composed of many individual light
  detections, each with its own lens
• What is molting?
• The process by which an arthropod sheds its
  exoskeleton and develops a new one.

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Phylum Arthropoda

• Identify the difference between chelicerae and
  mandibles.
• Chelicerae-pincerlike mouth parts
• Mandibles- jawlike mouth parts
• What are the five main subphyla of arthropods?
• Trilobita, Crustacea, Chelicerata, Myriapoda, and
  Hexapoda

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Subphylum Crustacea

• What characteristics are shared by most or all
  crustaceans?
• Have two pairs of antennae and paired appendages
  (some branched).
• Most have mandibles and a nauplius larva.

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Subphylum Crustacea

• What is the most important role of copepods in
  marine ecosystems?
• Abundant in the plankton and serve as a food
  sources
• What are some examples of terrestrial
  crustaceans?
• Sow bugs and pill bugs
• Why do terrestrial crustaceans only live in moist
  environments?
• They lack adaptations for conserving water

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Subphylum Crustacea

• Crayfish
• What are the functions of the mandibles and
  chelipeds on a crayfish?
• Mandibles are used for chewing
• Chelipeds are used for capturing food and
  defense.
• What structural adaptations of crayfish promote
  effective respiration in water?
• Walking and branches of maxillae circulate water
  over the gills.

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Subphylum Crustacea

• Crayfish (continued)
• Describe the type of circulation found in a
  crayfish.
• Open circulatory system the heart pumps
  hemolymph into several large vessels. Hemolymph
  then enters the spaces w/in the body where it
  bathes the tissues. Hemolymph returns to the
  gills where it exchanges O2 and CO2. Then, the
  hemolymph returns to the heart.

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Crayfish! Dorsal view
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Crayfish! Ventral view
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Crayfish!Internal view
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Subphyla Chelicerata and Myriapoda

• List the major characteristics of arachnids
• Have a cephalothorax and abdomen.
• Cepalothorax usually has 6 pairs of jointed
  appendages
• Chelicerae, pedipalps, and 4 pairs of walking legs

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Subphyla Chelicerata and Myriapoda

• Describe the functions of pedipalps
• Aid in holding food and chewing
• In spiders, they transfer sperm from the male to
  the females seminal receptacle.

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Subphyla Chelicerata and Myriapoda

• Describe three ways in which spiders are adapted
  to catching prey
• Some spiders spin webs to trap prey.
• They also have chelicerae modified as fangs that
  inject venom.
• Spiders can also immobilize their prey by
  wrapping them in silk.

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Subphyla Chelicerata and Myriapoda

• Name two ways in which scorpions differ from
  spiders
• Scorpions have large pincerlike pedipalps and a
  stinger at the end of their abdomen

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Subphyla Chelicerata and Myriapoda

• How do mites and ticks differ?
• Mites are usually less than 1 mm in length, while
  ticks are a few millimeters to 3cm in length.
  Mites can be free living, but ticks can only be
  parasites.

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Subphyla Chelicerata and Myriapoda

• How do millipedes and centipedes differ?
• Millipedes are herbivorous, have rounded bodies,
  and have two pairs of legs on most segments.
• Centipedes are carnivorous, have flattened
  bodies, and have one pair of legs on most
  segments.