Download The Arthropods

Chapter 16
 Largest phylum in Kingdom Animalia
 Anthropoda means “jointed feet”
 Includes lobsters, spiders, scorpions, millipedes, and
insects
 Can be harmful or helpful
 Harmful: destroy crops, eat other animals’ food, spread
diseases
 Helpful: studied by engineers; control the numbers of
harmful arthropods; help plants reproduce; make wax,
honey, medicine, and silk
 All arthropods have:
 Exoskeleton – their bones are outside of their body
 Chitin – allows the bones to be tough and flexible – they bend
without breaking
 Arthropods molt – as they grow, their exoskeleton becomes too
small – they outgrow the exoskeleton and throw it away
 Jointed appendages – their legs and feet have joints (bend)
 Body segmentation – most have 3 parts to their bodies
 Head
 Thorax (chest)
 Abdomen (belly)
 Open Circulatory System – they have a heart, but the blood goes
into the body parts after leaving the heart (not veins)
 Ventral Nervous System – Ganglia (nerves) are located near the
legs and connected to the brain by one cord
 Brain – located in the head
 Ganglia – nerves in the legs
 Ventral Nerve Cord – big nerve that connects the brain
and the ganglia
 Antennae – come out of the head and do taste, smell,
and touch
 Compound eyes – insects and crustaceans have these –
able to see all around, not just a few directions
______ OR_________
 Simple eyes – able to see very little, usually just light
and dark
 Lobsters, crabs, crayfish, shrimp
 Kingdom Animalia, Subkingdom Invertebrates, Phylum
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Anthropoda, Subphylum Crustacea
Usually live in the water
Carapace – the back plate of a lobster (the front has 6
plates)
Scavengers: they eat anything! They grind their food into
powder using the gastric mill.
They can regenerate (grow new parts)
Reproduce sexually – male gives sperm to the female in the
fall, female lays eggs in the spring that hatch in the
summer
 3 classes: Arachnida is the most important class
 Arachnids have:
 8 legs – 2 of these are pedipalps (legs used for sensing and
mating instead of walking)
 2 major segments
 Cephalothorax (head-chest)
 abdomen
 No antennae or mandibles (jaws)
 Have chelicerae instead (mouth that looks like fangs)
 Respiration by book lungs
 Breathe through their stomachs
 Usually 4 pair of simple eyes (8 eyes)
 Reproduce sexually – females are usually larger than males
 Scorpions, mites, and ticks
 80% of all animals are insects (bugs)
 There are 31 orders under Class Insecta
 Structure of Insects:
 Three pairs of legs (six legs)
 Usually have wings
 3 segments to the body
 Head
 Thorax (chest)
 Abdomen
 One pair of sensory antennae (2 of them)
 M0st insects have 2 pairs (4) wings
 Kinds of wings:
 Membranous wings: thin, transparent (see through) –
most common kind of wing - like a dragonfly or a bee
 Scale-covered wings: butterflies and moths
 Continued:
 Leatherlike wings: extra set of wings that protects the
wings used to fly – like a cover for wings – grasshoppers
have these
 Horny wings: ladybug wings – thick, protect the smaller
wings, cover the back of the bug
 Mouth:
 Upper lip - labrum
 Mandibles - used for chewing
 Maxillae – put food into the mouth
 Lower lip – labium
 Stomach:
 Foregut – behind the mouth – this is where salivary glands get
the food wet with spit before going to the gizzard to be
ground up into powder
 Midgut – where the stomach is – gastric ceca put more
digestive juices onto the food
 Hindgut – place right before the food is excreted (pooped)
 Respiration: insects breathe in their abdomens
through tubes called spiracles
 Circulation: the insects heart pumps blood into the
abdomen, where it covers the organs – no veins
 Excretion: Malpighian tubules are straws that pull
nitrogen out of the insect and put it into the intestines,
where it will become poop
 Reproduction: Sexual reproduction
 The male puts sperm in the female
 The female then lays eggs that will hatch later
 Metamorphosis means changing from a baby to an
adult
 There are two kinds of metamorphosis:
 Incomplete metamorphosis (3 stages)
 Grasshoppers, cicadas, and true bugs
 Egg
 Nymph (teenager – looks like a small adult) – only for insects
that stay on land (cicadas)
 OR
 Naiad – teenager that doesn’t look like the adult and lives in the
water (grasshoppers)
 Adult – the bug
 Complete metamorphosis (4 stages)
 Most insects – butterflies, flies, beetles, mosquitoes
 Eggs
 Larva – like a little worm (maggots, grubs, wigglers,
caterpillars) – childhood bug
 Pupa – teenager insect – usually inside a case called a cocoon
 Adult – the bug