ARTHROPODAPhylum

Major ClassesMajor Classes

• Arachnids: spiders, scorpions, ticks, mites

• Millipedes• Centipedes• Insects: beetles, flies, wasps, bees,

grasshoppers, crickets• Crustaceans: crabs, lobsters, crayfish,

shrimp, barnacles, copepods

Common Features of ArthropodsCommon Features of Arthropods

• Exoskeleton(external skeleton) is made of layers of protein and chitin, provides attachments for muscles, and is impermeable to water.

• Molting: shedding of cuticle in order to secrete a larger one. Makes the arthropod vulnerable.

• Open circulatory system: hemolymph fluid flows through open spaces (sinuses) which surround organs and tissues. Important for nutrient transport.

http://www.youtube.com/watch?v=zXhdr0TpOwY molting spider

Common Features of ArthropodsCommon Features of Arthropods (cont.)

• Tracheal system: branched tubes with chitin lining that carry O2 directly to cells (insects only)

• Spiracles: openings in exoskeleton that allow air to enter tracheal system (insects only)

Two body plans

• Head, thorax, abdomen

• Cephalothorax, abdomen

Insects: Mandibles and lots of mouth parts

Unique Arthropod FeaturesUnique Arthropod Features

• Mandibles: jaw-like feeding apparatuses contained by unimarians (centipedes, millipedes, insects) and crustaceans

http://www.youtube.com/watch?v=JRbgsCLaAQY camel spider eating a frog

It does not spin webs or have book lungs. Many rumors about the camel spiders’ speed, size and venom. In the middle east, it was said that these big, fast spiders would come into your tent at night and inject an anaesthetizing venom that would put its victims to sleep and feed on victim leaving a gaping wound. This is false, except that they do leave a large bite prone to infection.

Camel SpiderCamel Spider(class Arachnida; order Solifugae)(class Arachnida; order Solifugae)

http://www.youtube.com/watch?v=JRbgsCLaAQY camel spider eating a frog

Spiders use a fang like chelicerae equipped with poison glands to kill prey caught in web. Instead of fully chewing their prey, the spider will spill digestive juices onto prey. This softens the food and the spider will suck up the liquid.

Spider FeedingSpider Feeding

Unique Arthropod FeaturesUnique Arthropod Features (cont.) (cont.)

• Antennae: sensory organs that come in pairs on the organism’s head

• Compound eyes: eyes with many parts and multiple separate focusing elements

Metamorphosis: a relatively abrupt change in form or structure

Life CycleLife Cycle

Incomplete Metamorphosis: Incomplete Metamorphosis: grasshoppersgrasshoppers

Young are similar to adults, but have different body proportions and are smaller. There are a series of molts that eventually lead to the organism reaching full size.

Complete MetamorphosisComplete Metamorphosis

Larval stage - specialized for eating and growingPupal Stage - actual change occursAdult stage - specialized for reproduction

There are several distinct stages:

Centipede vs. millipede

• Centipede; fangs, venom,carnivore, fast moving 1 pair of legs per segment

• Millipede: slow, herbivore, rounder body, 2 pairs of legs per segment

http://www.youtube.com/watch?v=2f5gBFMMmGc giant cenitpede eating a tarantula

http://www.youtube.com/watch?v=1Jo9s80Tz-w&feature=PlayList&p=3260ECB787EF9616&playnext=1&index=7 giant millipede

More Arthopod

http://www.youtube.com/watch?v=IMPhL3lJaxY monarch emerges

http://www.youtube.com/watch?v=_QYhtMYYd9I nymph dragonfly: incomplete metamorphosis

http://www.youtube.com/watch?v=lE-8QuBDkkw bee hive

http://www.youtube.com/watch?v=U4P9azs5GS0 lobster walk

http://www.youtube.com/watch?v=eKPrGxB1Kzc&feature=PlayList&p=9C3A52D20A8D88F0&playnext=1&index=7 pistol shrimp

http://www.youtube.com/watch?v=SwoHVYS12oQ&feature=PlayList&p=9C3A52D20A8D88F0&index=8&playnext=2&playnext_from=PL mantis shrimp