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 7Mr. 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=ySXCdcnKBgg#

• http://www.youtube.com/watch?v=2N0lfprZ5iU

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