Arthropods Have Exoskeletons

1
Arthropods Have Exoskeletons Joints

• MOST INVERTEBRATES ARE ARTHROPODS
• Most common type of invertebrate arthropod
  invertebrate with segmented body covered by hard
  outer skeleton many pairs of legs insects,
  crustaceans arachnids are arthropods
• INSECTS ARE SIX-LEGGED ARTHROPODS
• CRUSTACEANS LIVE IN WATER AND ON LAND
• ARACHNIDS ARE EIGHT-LEGGED ARTHROPODS
• MILLIPEDES AND CENTIPEDES ARE ARTHROPODS

2
Arthropods exoskeletons

• Exoskeleton made of hard chitin, like suit of
  armor protecting it keeping it moist (if on
  land).
• Joints (where chitin is thin flexible) allow
  for movement muscles attach around joints for
  this.
• 3 main body parts Head, Thorax, abdomen
• Exoskeleton doesnt grow, it molts (sheds old one
  and grows new one) this is dangerous time
  because new one stays soft for awhile.

3
(No Transcript)
4
Insect 6 legged arthropods

• Arthropods have well-developed nervous
  digestive systems open circulatory system with
  blood moving into body without blood vessels
  reproduce sexually either male or female parts.
• As adults have 3 body segments, pair of antennae,
  6 legs attached to thorax.
• If on land, have spiracles (openings in
  exoskeleton to bring in oxygen).
• Many can blend in to environment, or have wings.
• Many are herbivores with designs for specific
  plants to eat (butterfly has tube to reach
  nectar)
• Some are social insects (bee, termite, ant)
  living in groups work together to get food,
  maintain nest care for offspring usually just
  one female (queen) lays eggs.

5
(No Transcript)
6
Insectmost common arthropod

• All insects reproduce sexually female lays many
  eggs(often with protective hard covering to keep
  from drying out)
• Insects undergo metamorphosis(3 stages of
  change) Egg hatches into Larva spends its time
  eating Pupasecond stage, insect body develops
  inside of protective casing Adult final stage,
  insect able to reproduce now
• Some insects skip some of the metamorphic stages
• Many larval stages are common (caterpillar,
  inchworm) often larva are very different
  (mosquito larva live in water feed on algae,
  pupa form on water surface adult flies off to
  feed on blood of animals lay eggs in water
  again).

7
Crustacean Arthropods

• Most live in water many used as food source in
  important food webs by humans.
• 3 or more pairs of legs 2 pair sensory antennae
• Most have heart but no blood vessels like other
  arthropods
• May eat plants/small animals, or remains of other
  organisms (barnacle is filter feeder)
• Barnacle larva is free swimming, then attaches as
  adult to hard surface (rock/boat/mollusk shell)
  uses its tentacles to grab food from surrounding
  water.

8
Arachnid- 8 legged arthropod

• Spiders, mites, ticks scorpions are arachnids.
• Exoskeleton, jointed limbs, segmented bodies
  (like all arthropods) but also have 4 pairs of
  legs and only 2 body segments no antennae
• Some are parasites(tics,chigger mites), others
  are predators (spiders scorpions). These get
  prey by stinging, biting or injecting venom.
• Most arachnids are spiders. Make strong silk to
  form webs to capture food. Spinnerets at rear of
  abdomen spins strands of silk into web.
• Some arachnids have spiracles to get oxygen,
  while others (some spiders) have book lungs
  (moist folded pockets within abdomen).

9
(No Transcript)
10
Millipede Centipede Arthropods

• Both have long, segmented bodies with many legs.
  
• Reproduce sexually, hatch from eggs.
• Millipedes have 2 pair of walking legs on each
  body segment move slowly eat decaying leaves
  plant matter may emit foul odor if disturbed
  which may harm predators.
• Centipedes move quickly, have 1 pair of legs per
  segment, have antennae jaw-like mouthparts.
  Many have pincers on rearmost segment. Are
  predators that can paralyze prey.

11
(No Transcript)