Crustaceans, Spiders and Insects

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Arthropods

• Crustaceans, Spiders and Insects

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What is an Arthropod?

• Arthropods are the most successful phylum on the
  planet!
• 750,000 species
• Arthropods have
• Segmented body
• Tough exoskeleton
• Jointed appendages

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Form and Function

• Feeding complex mouthparts to eat a wide range
  of food
• Respiration
• Land air enters through spiracles holes in
  the side of the body.
• Water gills or book gills
• Circulation open circulatory system open
  sinuses
• Excretion Malpighian tubules saclike organ
  that combines urine and waste together
• Response have a brain! Sophisticated eyes and
  taste receptors
• Movement have musclescan flex and extend
• Reproduction internal or external reproduction
  depending on the species

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Groups of Arthropods

• Crustaceans primarily aquatic
• Examples crabs, shrimps,
• crayfishes and pillbugs.
• Characteristics
• Two pairs of antennae
• 2 or 3 body sections Cephalothorax/Abdomen
• Chewing mouthparts called mandibles

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Growth and Development

• Molting when arthropods outgrow their
  exoskeleton
• Steps to molting
• 1. skin glands digest inner part of exoskeleton
• 2. other glands create a new exoskeleton
• 3. animal pulls itself out of old skeleton
• 4. While new skeleton is soft animal fills it
  with air to allow for growth

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Groups of Arthropods

• 2. Spiders and their relatives
• Characteristics
• No antennae
• Cephalothorax and abdomen
• 2 pairs of mouthpart appendages
• Chelicerae fangs to stab and paralyze prey
• Pedipalps grab prey
• Spiders are in the class Arachnida
• Spiders have no jaws so they liquify their prey
• Scorpions are found in warm climates.
• The abdomen has a stinger that can kill
• and paralyze prey.

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Groups of Arthropods

• 3. Insects
• There are 3 classes of Insects
• 1. Chilopoda centipedes
• 2. Diplopoda millipedes
• 3. Insecta the insects
• Centipedes
• each body segment has one pair of legs
• carnivores
• live beneath rocks or in the soil
• 2. Millipedes each body segment has two pairs
  of legs

• Dragon Millipede produces cyanide when
  threatened.

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Insects, Contd.

• Insects have a body divided into three parts
• Head antennae and eyes
• Thorax - three pairs of legs, wings
• Abdomen stinger or poison gland

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Insect Reproduction

• Insects undergo metamorphosis a process of
  changing shape and form.
• Incomplete Metamorphosis Young (called nymphs)
  look very much like the adults.
• Examples Grasshoppers

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Insect Reproduction

• 2. Complete metamorphosis dramatic change in
  body form. EggsLarvaePupaAdult
• Examples bees, moths, beetles, butterflies,
  flies