Introduction to Phylum Arthropoda

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From Greek “Arthro-jointed”, “podis”-feet Segmented body. Paired segmented appendages. Chitinous exoskeleton. Open circulatory system, a tubular dorsal blood vessel. Striated muscles in skeletal system. Respiration by gills, tracheae, or spiracle.

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Insects (winged arthropods) Arachnids (spiders, ticks, mites, etc.) Crustaceans (isopods, crabs, lobsters) Millipedes Centipedes

CUES, http://www.entomology.umn.edu/cues/IPM-turf/sodwebworms.htm

Sod Webworm Moth, Crambus sp.

Cottonwood Leaf Beetle, Chrysomela scripta

• Two main body sections. • Five to seven pairs of legs. • Two

O.F.A.H. http://www.invadingspecies.com/

pairs of antennae. • Simple eyes. • Gills Crayfish

Pillbugs are land dwelling crustaceans complete with gills, that’s why they stay in humid areas under rocks!

• One pair of legs per body segment. • Flattened body. • First pair of legs modified as venomous fangs. • Nocturnal predators. • Few are dangerous to humans. Garden Centipede, Lithobius forficatus

Department of Entomology, University of Nebraska-Lincoln

Georgia Forestry Commission Archives Georgia Forestry Commission www.forestryimages.org

Fangs of Scolopendrid Centipede (above) House Centipede, Scutigera coleoptrata (right) Department of Entomology, University of Nebraska-Lincoln

• Two pairs of legs per body segment. • Cylindrical body. Rounded appearance • Feed on decaying plant material. • Herbivorous • Nocturnal. • Harmless.

Emily G. Tenczar

Pet African Giant Millipedes

Photos by William Leonard, Tree of Life Web Project, http://tolweb.org/tree/phylogeny.html

Pseudoscorpion

Tick

Mite

Yellow Garden Spider

Ronald F. Billings Texas Forest Service www.forestryimages.org

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Mouthparts are called chelicerae. Most contain venom. Antennae are absent. Four pairs of legs. 1 to 2 body segments.

Blacklegged Tick, Ixodes scapularis Scott Bauer, USDA Agricultural Research Service, www.insectimages.org

Yellow Garden Spider, Argiope aurantia

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Two body regions (cephalothorax, abdomen). Fangs (chelicerae), most are venomous. Most are not dangerous. Jumping Spider, Phidippus Most make webs. audax Most have poor eyesight; hairs compensate for it (jumping spiders are an exception). Potentially dangerous spiders (bites are uncommon): Brown recluse spider, Black widow spider David Cappaert, www.insectimages.org

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Mites have only one noticeable body region. Many are microscopic or close to it.

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One apparent body region. Abdomen and cephalothorax short. Common and harmless. Nocturnal. Feed on detritus, fruit, or other animals. Leiobunum sp.

Joseph Berger, www.insectimages.org

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One apparent body segment Looks like scorpion without tail Very small soil dweller Pedipalps or pinchers resemble those of scorpions  Source of venom

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Harmless predators of soil insects

Notice Size

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Six legs Protruding mouthparts, unlike non-insect hexapods. Most have wings. David Cappaert, www.insectimages.org

Milkweed Leaf Beetle, Labidomera clivicollis

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Small- Soil dwelling. Furcula or fork-like springing structures. Simple eyes. Antennae. Wingless adults. Compact body Feed on decomposing materials. David R. Maddison, Tree of Life Web Project http://tolweb.org/tree/phylogeny.html

Japanese Beetle, Popillia japonica, Adult (left) and Scarab Larva (below)

Elytra

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Hardened forewings (elytra). Elytra divided evenly down the back Winged adults. Chewing mouthparts. Note elytra division pattern like a “T” shape

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Piercing/Sucking mouthparts. Usually winged adults. Wings criss-cross against back, form an hour-glass outline. Nymphs and adults similar in appearance.

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Most bugs feed on plants. Some are predaceous.

Note “X” to hour glass shape of back and elytra

CUES, http://www.entomology.umn.edu/cues/dx/vk/fourbug.htm

CUES http://www.entomology.umn.edu/cues/dx/vk/whitemark.htm

Fourlined Plant Bug, Poecilocapsus lineatus

Predaceous Stink Bug attacking caterpillar

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Three tail-like appendages. Body flattened and covered with scales (like butterflies) Wingless adults. Three tails (fillaments) Found in wet places. Lepisma saccharina

Clemson University - USDA Cooperative Extension Slide Series www.insectimages.org

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“Skin-like” front wings. Abdomen ending in pinchers (cerci) Chewing mouthparts.

Striped Earwig, Labidura riparia

Joseph Berger, www.insectimages.org