ARTHROPODS

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ARTHROPODS

• BIOLOGY PROGRAM
• MOUNTAIN POINTE HIGH SCHOOL

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Animals of Phylum Arthropoda

• Termites, ticks, scorpions, grasshoppers, flies,
  mosquitoes, lobsters, crabs, bugs,spiders,
  centipedes, millipedes, daphnia,crayfish,beetles,d
  ragon flies, bees, wasps, daddy-long legs, mites,
  fleas, trilobites, butterflies, moths, barnacles,
  ants,..and many many more!!!!!

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ARTHROPOD CLASSES
ARACHNID - SPIDER CRUSTACEAN - LOBSTER,
SHRIMP INSECTA - BEE, GRASSHOPPER CHILOPODA -
CENTIPEDE DIPLOPODA - MILLIPEDE
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Characteristics of Arthropods !!

• Invertebrates with an exoskeleton!
• Jointed appendages (legs)
• Bilaterally symmetrical, protosome
• Has a true coelom, mesoderm
• Segmented body

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What are the advantages or disadvantages of an
exoskeleton??

• Protection -made of chitin and protein- hard and
  thick !!
• Supports internal organs
• Provides for muscle attachment
• Heavy-disadvantage
• Cant grow, so it must be shed by molting
  periodically!

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Segmentation

• Most arthropods have three body segments! HEAD,
  THORAX, and ABDOMEN

• Sometimes the head and thorax are fused together
  to form a CEPHALOTHORAX- like in lobsters!

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How do Arthropods breathe??

• Some land Arthropods breathe through tiny
  openings on their body called spiracles which
  lead to tubes within the body called tracheal
  tubes! - crickets!
• Other land arthropods (spiders) breathe using
  book lungs found just behind the legs on the
  body!

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Senses found in Arthropods!- from a brain and
ventral nerve chord!!!

• Antennae are sensitive to movement, sound and
  chemicals! They are used for communication too.
• Pheromones are chemical-odor signals given off by
  arthropods!
• EYES - both simple and compound! (Simple eyes
  detect light/dark! Compound eyes have many lenses
  together forming an image! Excellent for
  detecting movement!)

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Sight through a Bees Compound Eye
Bee Sight
Human Sight
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Circulation and Digestion in Arthropods!

• Open circulatory system- blood flows into spaces
  in the body- not kept in blood vessels!
• Dorsal heart !
• Complete digestive system-mouth-crop-stomach-intes
  tines-anus!
• Digestive enzymes breakdown food!
• Chewing mandibles , or sucking mouth parts are
  strong!
• Malpigian Tubules filter wastes into the
  intestines!

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Sexual Reproduction in Arthropods !

• Internal Fertilization- eggs protected inside
  female.
• A few are hermaphrodites
• Some show parthenogenesis- young forming from
  unfertilized eggs!

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Arthropods and Humans ??
The Good, the Bad and the Ugly!!!

• Great pollinators bees, wasps!
• Provide honey, shellac, wax and silk!
• Alternative to pesticides - lady bugs, praying
  mantis
• Used in genetic research to make artificial skin,
  surgical sutures, and anti-fungal medicine from
  crab shells!
• Problems eating our food!
• Spread diseases- malaria, yellow fever!

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Diversity - The Arachnids!!- spiders,
scorpions, mites, and ticks!

• 30,000 species of spiders - but only about a
  dozen are poisonous to humans!
• 2 body parts - cephalothorax and abdomen!
• Appendages- 2 Chelicera-fangs, two pedipalps for
  handling food and used in reproduction, and 8
  legs!!
• 2-6 silk glands in the abdomen-passing the liquid
  silk to the spinnerets which knit it into thread!
• No mandibles - but a sucking stomach!
• No antennae / Simples eyes -usually 8

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Arachnids
Chelicera
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Diversity - The Crustaceans - crayfish, shrimp,
lobsters, barnacles, crabs!

• Gills for breathing
• Large mandibles for crushing food!- jaws open
  side to side not up and down!
• 2-pairs of antennae!
• 2 stalked compound eyes!
• 5 or more pairs of walking legs with 2 large
  chelipeds called pinchers!
• No malpighian tubes --gt mouth and anus

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Crustacean Example - Crayfish
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Diversity-Centipedes and Millipedes

• Class Chilopoda- centipedes with one pair of legs
  per segment!
• Centipedes are carnivorous- eating snails, slugs
  and worms- They bite!!
• Class Diplopoda - millipedes with two pairs of
  legs per body segment!
• Millipedes are herbivorous - eating roots and
  leaves
• Millipedes dont bite but they can spray a
  smelly-fluid from their stink glands!

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Centipede Millipede
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INCOMPLETE METAMORPHOSIS
COMPLETE METAMORPHOSIS
The young looks totally different from the adult
version. Ex. Larva - Pupa
The young is a small version of the adult Ex. Egg
- nymph - adult
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Diversity-The Insectsbugs.com

• 3-body parts- head-thorax-abdomen
• Spiracles-tracheal tubes for breathing
• 3-pairs of legs- antennae, both simple and
  compound eyes-
• A tympanum for hearing
• Sometimes wings- one or two pair
• Malpighian tubes
• Complete Metamorphosis- (butterflies-moths)
  egg-larva-pupa-adult !!
• Incomplete Metamorphosis-( crickets,
  grasshoppers) egg- nymph-molt-nymph-molt-nymph-mol
  t-adult

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Complete Vs Incomplete Metamorphosis