Transcript Mollusks, Worms, Arthropods, Echinoderms

DO NOW
• Pick up papers on the chair
• Read over the crayfish activity
• Answer on the Lab
– What is the difference between an arthropod
and a mollusk?
• 10 o Clock Buddies
Agenda
• Discovery
• Notes
• Tick Brochures (?)
Crayfish
Dorsal Side
Ventral Side
Arthropods
Science 7
Mr. D
Arthropods
• Characteristics – Phylum: Arthropoda
– Largest group of animals
– Have jointed appendages which include legs,
antennae, claws, wings, and pincers
– Have bilateral symmetry, segmented bodies,
exoskeletons, a body cavity, a digestive system
with two openings and a nervous system
– Most have separate sexes and reproduce sexually
– Open circulatory system
– Use air tubes, book lungs, and gills to obtain
oxygen
Arthropods
• Body Segments
– Bodies of these animals are divided into segments
similar to segmented worms
– Some have many segments, others have
segments that are fused together to form body
regions
• Exoskeleton
– A hard outer covering that supports and protects
the internal body and provides places for muscle
to attach.
– Doesn’t grow as the animals does, it is shed and
replaced during a process called molting
What are they
•
•
•
•
•
Crustaceans
Centipedes
Millipedes
Spiders and their relatives
Insects
Crustaceans
• Have one or two pair of antennae and
mandibles, which are used for crushing
food.
• Most live in water, but some live in
moist environments on land—such as
pill bug.
• Have five pair of legs, first pair of legs
are claws for catching and holding food.
Crustaceans
• Swimmerets are appendages on the
abdomen which help in movement and
are used in reproduction; also force
water over the gills used in O2 and CO2
exchange
• If a crustacean loses an appendage it
can regenerate it
Who are they?
•
•
•
•
Crabs
Lobsters
Barnacles
Shrimp
Centipedes & Millipedes
• Have long bodies and many segments,
exoskeleton, jointed legs, antennae and
simple eyes.
• Found in damp environments
• Reproduce sexually
• Make nests for eggs and stay with them until
they hatch.
• Centipedes are predators
• Millipedes feed on decaying plant matter.
Meet the Arachnids
•
•
•
•
Spiders
Scorpions
Ticks
Mites
Arachnids
• Have two body regions
– Cephalothorax and an abdomen
• Four pairs of legs and no antennae
• Many are adapted to kill prey with
poison glands, stingers, or fangs
• Some are parasites
Arachnids
• Scorpions
– Have sharp, poison filled stinger at the end of
abdomen.
– Have a well-developed appendages which they
can grab their prey.
• Spiders
– Can’t chew their food, release enzymes into prey
to digest it—then suck the predigest liquid into its
mouth.
– Have book lungs where O2 and CO2 are
exchanged.
Arachnids
• Mites & Ticks
– Most are parasites
– Ticks have specialized mouthparts to
remove blood from the host.
– Ticks often carry disease such as Lyme
disease.
Value of Arthropods
• A source of food
• Agriculture would be impossible without
bee pollination
• Useful chemicals are obtain from some
arthropods
• Important part of ecological community
Origin of Arthropods
• Some fossils are more than 500 million years
old
• Scientist hypothesized that arthropods
probably evolved from an ancestor of
segmented worms because they have body
segments
• The hard exoskeleton and walking legs
allowed arthropods to be among the first
animals to live successfully on land
Video
• http://www.youtube.com/watch?v=ySXCdcnK
Bgg#
• http://www.youtube.com/watch?v=2N0lfprZ5
iU
Activity
• Design a series of signs to be used along hiking
trails in national parks to remind hikers of ways to
protect themselves from ticks
DO NOW
• Take out your homework and Notesheet
• Answer this question – How are arthropods
different from sponges and cnidarians?
• Agenda
– Finish lecture
– Insects
– Zebra Mussels