ARTHROPODS

Insects• Shrimp

•Centipedes

•Lobsters

Millipedes

Arthropods are the most successful animals!

•They are found in many environments.

•They can ADAPT to many environments.

Phylum: Arthropoda

Characteristics:• Arthropoda means jointed foot• Appendages grow from the body• The body is divided into three

segments:– Head ~ 1st part, contains the sense organs– Thorax ~ middle, joins head & abdomen

walking legs are attached here

-Abdomen ~3rd part, reproductive & digestive organs are found here

All arthropods have an external skeleton called the

exoskeleton.

The exoskeleton has several functions:

*covers

*supports

*protects

*prevents from drying out

Arthropods molt their exoskeleton.

Molting is a process of shedding the exoskeleton and replacing a new one in order to grow.

What problems do you see with this process?

Class ~ Crustacean

Types of Crustaceans

Crabs

Lobsters

Shrimp

• Pill bug

• Barnacles

• Water fleas

CharacteristicsCephalothorax- head & thorax fused togetherOne or two pairs of antennaeMandibles ~ jaws used for crushing foodFive pairs of legs:1st pair~ claws, catching food, protectionFour pairs of walking

Swimmerets ~ appendages on the abdomenMovementReproductionForce water over the gills for breathingRegenerate lost appendages

CRAYFISH~ A common crustaceanCRAYFISH~ A common crustacean

• Cephalothorax and abdomen• Two pairs of antennae

Shorter pair-Touch, taste, balance

Longer pairTouch, taste, smell

• Compound eyes ~ located at the end of the eye stalks

– Why is this an advantage?

Class ~ Insecta

Insects: Largest class of Arthropods

• Most successful animals: – reproduce in mass numbers – lives in many environments

Characteristics of Insects:

• 3 body parts: head, thorax, abdomen

• Mandible- specialized mouth part

• Antenna or feelers for touch or smell

• 1 or 2 pairs of wings

• Reproduction- sexual• Complete metamorphosis

• Incomplete metamorphosis

Grasshopper

• Most common insect

• Two types of eyes- simple & compound

• 3 pairs of legs:– 1st two pairs- walking– 3rd pair- jumping

Grasshopper (cont.)

• two pairs of wings

• spiracles- found on the abdomen for respiration/breathing

• Reproduction- sexual– Incomplete metamorphosis:

• Egg, nymph, adult

Metamorphosis

• A series of distinct changes in form through which an organism passes as it develops from an egg to an adult.

• Complete Metamorphosis (4 stages):– egg- larva–pupa-adult

• Incomplete (3 stages):– egg- nymph-adult

Class ~ Arachnid

Characteristics

• Two body parts:– Cephalothorax: head & thorax fused together– Abdomen

• no antennae

• four pairs of legs

• poison glands, stingers or fangs

• four pairs of simple eyes

Spider Chelicerae

Fangs, Chelicerae of Zebra Jumping SpiderSalticus scenicus

www.microscopix.co.uk/spiders/fangs/index.htm

Fangs and Chelicerae of Tarantula SpiderlingBrachypelma smithi(Mexican Red-Knee Tarantula)

SPIDERS

• A common arachnid• Eight compound eyes to sense light and darkness• Cannot chew food ~ inject poison into their prey

which paralyzes it and then turns the food into liquid

• Book lungs ~ series of flat, air filled plates used in respiration

• Spiracles~ openings in the abdomen that allow oxygen in and carbon dioxide out

Some arachnids are parasites!

• TICKS– Rocky Mountain Fever

– Lyme Disease

• MITES– Chiggers

– House dust mites

– Eyelash mites

Class: Centipede

• 1 pair of legs per body segment

• usually a flat body• 1 pair of antenna• feed on insects and

spiders• move fast

Class: Millipede

• 2 pairs of legs per body segment

• rounded body• 1 pair of antenna• feed organic matter-

leaves and wood• move slow

Arthropod Review

• How many classes of Arthropods?

• 5

• Name the classes

• Crustaceans• Insects• Arachnids• Centipedes• Millipedes