Post on 16-Dec-2015
transcript
Phylum ArthropodaTextbook pgs. 335-342
Spiny-backed orb weaver
Arthropod Classes• Crustaceans• Insects• Centipedes• Millipedes• Arachnids• Trilobites
(extinct)
Body Characteristics• Body Symmetry: Bilateral symmetry• Cell Organization: Cells to tissues to organs to
organ systems• Reproduction: Sexual• Body development: Most arthropods go through
METAMORPHOSIS
Just the facts…Just the facts…1. Fully developed to life
on land2. No need of a moist
environment3. Only invertebrates to
fly.4. Live in salt and fresh
water, soil, land, air5. Size ranges from tiny
mites to over 3 feet.6. Largest phylum in the
animal kingdom.
Characteristics of Arthropods• Invertebrate
• External skeleton-Exoskeleton
• Segmented body• Jointed attachments called
appendages– Wings, mouthparts, antennae,
legs
• Open circulatory system• Internal fertilization
– most reproduce sexually– They are EITHER male or
female
An Arthropod Exoskeleton• Waterproof shell– Used for protection– Helps prevent
evaporation, keeps them from drying out
– Place for muscle attachment
• Made out of chitin• As the arthropod grows
larger, it can’t expand, so it must shed its exoskeleton– Process called molting Pillbug molting its exoskeleton
Molting
The difference between a soft-shelled crab and a hard-shelled crab
Adult cockroach
A horse-shoe crab.
CRUSTACEANS•CEPHLATHORAX
and ABDOMEN•(2 BODY PARTS)
•GILLS FOR BREATHING
•HARD OUTER SHELL
Fiddler Crab
Crustacean Body Segments
• Head and thorax combined– Cephlathorax
• Then an abdomen
ARACHNIDS• Head and
Abdomen– Four pairs of legs
• Breathe with organs called book lungs
• SOME BUT NOT ALL BUILD WEBS
Tarantula Scorpion
TickBlack Widow
CENTIPEDES• 2 body sections–Head with antennae– Long segmented
abdomen
• 100 LEGGER• ONE PAIR OF
LEGS PER SEGMENT
• LONG, FLAT BODIES
• CARNIVORES
MILLIPEDES• 2 body sections–Head with
antennae– Abdomen with at
least 80 segments• “1000 Legger”• Most of the body
segments bear two pairs of legs.
• Rounder bodies• Feed on decaying
vegetable matter and are herbivores
Will curl up to avoid predators.
Insects
• The Importance of Insects:• Pollination of flowers• Destroy harmful pests• Make silk fibers–Larva of the silkworm moth
• Make food products–Bees make honey
Insect Impact on Humans
• Damage to major crops
• Can carry diseases – Ex. – some
mosquito species cause malaria
Mosquito on Human Skin
Why Insects are So Successful
• Reproduce very quickly (short generation time)
• Females produce many young
• Ability to eat a variety of foods
Why Insects are So Successful• Different species
have become adapted to live in almost ANY environment
• Ability to fly (can travel for food and mates)
Mosquito in Flight
Insect Body Structure• Insects have:
Three body parts• HEAD, THORAX, ABDOMEN
3 pairs of legs attached to the thorax
1 pair of antennae attached to the head
Insect Body Structure
Simple and compound eyes
Most insects have one or two pairs of wings attached at the thorax
Many have tubes (spiracles) which allow oxygen to travel directly to the insect’s body cells
Insect Metamorphosis• Gradual
Metamorphosis: the egg hatches into a young insect that looks like the adult, only smaller– Ex. Grasshoppers,
termites cockroaches and dragonflies
• 3 stages – • 1.The egg • 2. hatches into a nymph• 3. the nymph molts
several times growing into a larger nymph
• 4. eventually becoming the adult.
Insect Metamorphosis cont’d• Complete
Metamorphosis: the young insect looks very different from the adult form– Ex. Butterflies,
beetles, houseflies, and ants
• 4 stages – 1. The egg hatches into
a2. larva, 3. the larva forms pupa,
and 4. the pupa turns into
an adult.
Insect Examples
Black Blister Beetle
Thistle Caterpillar
17-year Cicada
Insect Examples
Weaver Ants
Robber Fly Catching a Bee for DinnerTropical
Cockroach
Moss Mantid
TRILOBITES• ONCE THE
LARGEST GROUP OF ARTHROPODS
• EXTINCT.
Comparison of the largest Arthropod Groups
Characteristic Crustaceans Arachnids Insects
# of Body Sections
2 or 3 2 3
# of legs 5 or more pairs
4 pairs 3 pairs
# of antennae 2 pairs 0 1 pair
Where found Water or damp places
Mostly on land
Mostly on land
Example Lobster Tarantula Praying mantis
Arthropod Review