Creatures of the “Jointed Legs” Phylum Arthropoda Creatures of the “Jointed Legs”

Phylum Arthropoda I. Characteristics of Arthropods A. Chitinous exoskeleton (or cuticle) divided into segments, creating what is called metamerism. B. Jointed Appendages C. True Coelomates D. OPEN circulatory system E. Advanced nervous and muscular systems F. Respiration by trachea, book lungs, body surface, or gills G. Sexes are usually separate males and females H. Molting or shedding of exoskeleton is called ecdysis.

II. There are six major classes of Arthropods A. Class Insecta – The largest and most successful class of organisms in the world. B. Class Crustacea – mostly aquatic; shrimp, crabs, lobsters, crayfish, etc. C. Class Arachnida – spiders, mites and ticks D. Class Chilopoda – venomous centipedes E. Class Diplopoda - nonvenomous millipedes F. Class Merostomata (Xiphosuridae) – The Horseshoe Crabs

III. Classification A. Insecta 1. Three body segments – Head, Thorax and Abdomen 2. Three pairs of legs – all attached to the thorax 3. Some insects live socially, sharing a division of labor 4. Some insects carry out Metamorphosis a. complete metamorphosis – significant change such as that seen in butterflies or beetles b. Incomplete metamorphosis – not so great a change such as seen in crickets or grasshoppers 5. Defense includes stings, mimicry, protective or warning coloration, secretions, bites, and sprays.

III. Classification A. Insecta (continued) 6. Excretion carried out by Malpighian Tubules. 7. Sense of hearing carried out by setae on tympanic structures, or by feeling substrate with their legs. 8. Visual reception is carried out with either simple eyes or compound eyes. Some can actually detect color. 9. Parthenogenesis (Strange asexual reproduction) in the life cycle of some Hymenopterans and Hemipterans, but most have sexual reproduction with separate sexes. 10. Sexual Reproduction takes place between most, with separate males and females. 11.Shedding or molting of the exoskeleton is called Edysis. 12. Like all animals, cockroaches are susceptible to nuclear radiation, but they ARE highly adaptable.

Lady Beetle flying in slow motion https://www.youtube.com/watch?v=fC61ZA4uWbs Wasp and Bee stings in slow mo https://www.youtube.com/watch?v=0eTN3uN_VM0

Incomplete Metamorphosis – Egg Nymph Adult

Complete Metamorphosis Egg Larva Pupa Adult

Most Common Insect Orders: Now 30 orders recognized Diptera – Flies and Mosquitos Orthoptera – Grasshoppers, Crickets, and Roaches Coleoptera – Beetles Lepidoptera – Butterflies and Moths Hymenoptera – Ants, Bees, and Wasps Isoptera – Termites Hemiptera – True Bugs Odonata – Dragonflies Siphonaptera – Fleas Neuroptera - Lacewings

B. Arachnida 1. Two body segments –Cephalothorax & Abdomen 2. Four pairs or 8 legs 3. Eight simple eyes 4. Anterior appendages called chelicerae have fangs 5. Only two dangerous species in the USA Black Widow Brown Recluse

Interesting spider venom tidbits: The venom of the Black Widow is a neurotoxin, and causes : Paralysis

Interesting sider venom tidbits: The venom of the Brown Recluse is a hemolytic toxin, and causes necrosis

Other Arachnids Dust Mite Scorpion Harvestman (Commonly misnamed Daddy-Longlegs) NOT venomous!

Other Arachnids: 1. Dust mites (about 40,000 species) live in house dust, and in mattresses; redbugs (chiggers) are mites. 2. Scorpions (about 1,400 species) feed largely on insects and spiders at night. 3. Harvestmen (about 5,ooo species) are harmless to to humans and protect themselves by excreting noxious secretions, and can escape by shedding legs. 4. Ticks have an anasthaetic and an anticoagulant in their saliva.

C. Crustacea (crabs, shrimp, lobsters, crayfish, pillbugs ) 1. Two pairs of antennae 2. Gills used for respiration 3. Usually five or more pairs of legs including pincers (in most species) called chelipeds. 4. Mostly aquatic – a few are terrestrial. 5. Sharp tail stucture known as a telson. Pillbugs (Sowbugs)

More Crustaceans

Other Crustaceans Blue Crayfish

“Centipedes – The creatures of a hundred legs” D. Class Chilopoda “Centipedes – The creatures of a hundred legs” Numerous body segments with ONE pair of legs per segment – except the one behind the head and the last two. They DO NOT have 100 legs! 2. Hollow fangs produce toxins to kill prey 3. Carnivorous – Eat primarily worms and insects, some dangerous to humans through painful bites. https://www.youtube.com/watch?v=8iVXvAWyNBM

E. Class Diplopoda “ millipedes: creatures of a thousand legs” 1. Numerous body segments with TWO pairs of legs per body segment, except the one behind the head and the last two. 2. Produce a noxious secretion and coil up when threatened 3. Herbivorous – They eat decaying organic matter and leaf litter. A Typical Millipede http://www.youtube.com/watch?v=KCIRPTGsPtQ

F. Class Merostomata also known as Xiphosurida Horseshoe Crab 1. Horseshoe shaped carapace or dorsal surface. 2. Long, fused telson, or tailpiece, also found in crustaceans 3. Reproductive cycles very important to shorebird migration Horseshoe Crab

Interesting Facts Molting in Arthropods is called ECDYSIS. The chitinous exoskeleton is also known as the CUTICLE. COCKROACHES, like all other animals are susceptible to nuclear radiation, but they ARE highly adaptable, allowing them to live in any habitat.

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