ArthropodaPhylum Arthropoda Subphylum Chelicerata Class Merostomata (horseshoe crabs)

Class Pycnogonida (sea spiders)

Class Arachnida (spiders, scorpions, ticks, mites)

Brown Recluse

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Black Widow Lone Star Tick Dust Mite

Subphylum Crustacea Class Malacostraca (crayfish, lobsters, crabs, shrimps)

Crayfish

Lobster

Shrimp

Spider Crab

Order Isopoda (pill bugs, sow bugs)

Class Cirripedia (barnacles)

Class Remipedia Class Cephalopcarida Class Branchiopoda Class Ostracoda Class Copepoda Class Mystacocarida Class Tantulocarida Class Branchiura

Subphylum Uniramia Class Chilopoda (centipedes)

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Class Diplopoda (millipedes)

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Class Symphyla

Class Pauropoda Class Insecta Order Thysanura (silverfishes)

Order Ephemeroptera (mayflies)

Order Odonata (dragonflies, damsel flies)

Order Isoptera (Termites)

Dragon Fly Damsel Fly

Order Dermaptera (Earwigs) Order Anoplura (Sucking lice)

Order Neuroptera (ant lions, lacewings)

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Ant Lion Green Lace Wing

Order Coleoptera (beetles – ladybugs, fireflies, boll weevils)

Eastern Hercules Beetle

Lady Beetles Tiger Beetle

Order Lepidoptera (butterflies, moths) Giant Swallowtail Leopard Moth

Order Diptera (flies, mosquitos, gnats, midges)

Asian Mosquito

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House Flies

Order Siphonaptera (fleas)

Cat Flea

Order Hymenoptera (bees, ants, wasps, hornets) Fire Ants

Mud Dauber

Order Orthoptera (grasshoppers, crickets)

Bumble Bee

Cave Cricket Rainbow Grasshopper

Order Phasmida (walking sticks) Order Mantodea (praying mantids)

Order Blattaria (cockroaches)

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Order Homoptera (cicades, aphids, leaf hoppers, scale

insects)

Cicada

Green Peach Aphid

Citrus Mealy Bug

Leaf Hopper

Order Hemiptera (true bugs – water strider, water boatmen, back swimmers, bedbugs, squash bugs, stink bugs, assassin bugs)

Water Strider

Water Boatman

Assassin Bug Stink Bug

Squash Bug

Order Protura (eyeless insects) Order Collembola (springtails)

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Order Diplura (small, blind, wingless insects) Order Microcoryphia (jumping bristletails) Order Plecoptera (stone flies) Order Embioptera (web spinning insects) Order Psocoptera or Corrodentia (book lice, bark lice, &

psocids)

Order Zoraptera (small, pale, soft-bodied insects resembling tiny termites)

Order Mallophaga (chewing lice & bird lice)

Order Thysanoptera (thrips)

Order Strepsiptera (minute, beetle-like insects, mostly

parasitic on other insects) Order Mecoptera (scorpion flies)

Order Trichoptera (caddis flies & water moths)

Caddis Fly Characteristics of Arthropods -segmented bodies with paired, jointed appendages -bilaterally symmetrical -coelomates -chitinous exoskeleton -protostomes -aerial, terrestrial & aquatic forms -75% of all animals are arthropods -about 1,000,000 species 8

Appendages - jointed extensions such as legs and antennae found in

Arthropods. Compound Eyes – eyes composed of many individual light detectors, each

with its own lens; found in most arthropods.

Molting – due to an external skeleton, an arthropodcannot grow without

periodically shedding its exoskeleton. - arthropods molt many times during its life, with each molt it becomes larger.

Evolution & Classification -arthropods first appeared more than 600 million years ago -ancestral arthropods had bodies consisting of many segments that

were nearly identical. -arthropods are divided into four subphyla Tagmata – a structure composed of several segments that have fused

to perform specific functions, found in arthropods. Subphylum Trilobita – extinct animals called trilobites, which had

similar paired appendages on each body segment.

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Subphylum Crustacea -two pairs of antennae -chewing mandibles -appendages with two branches -predominantly aquatic -small species exchange CO2 & O2 through the

thin areas of their exoskeleton -larger species respire through gills -about 40,000 species Nauplius -the developing of an embryo into a free swimming larva

-three pairs of appendages -single eye in middle of head -takes on adult form through a series of molts

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Plankton - the collection of small organisms that drift or swim weakly

near the surface of a body of water. - composed mostly of Copepods.

Daphnia Cirri – found on barnacles which are sessile - six pairs of long legs which are covered with hairlike setae - extend through opening in the shell - sweeps small organisms and food particles from the water into

the mouth.

Isopods – means “equal legs” - seven pairs of identical legs - some Isopods are terrestrial such as Pill bugs & Sow bugs The Crayfish Freshwater crustacean Decapod “ten feet” External Structure Cephalothorax – the major section of the crayfish that consists of two

tagmata: the head, which has five segments, and the thorax, which has eight segments and lies posterior to the head.

Carapace – a tough covering over the cephalothorax of some

crustaceans. Abdomen – the tagma that lies posterior to the cephalothorax & is

divided into seven abdominal segments. Telson – the seventh abdominal segment that forms a flat paddle at

the posterior end of the crayfish. Antennules – serve as feelers sensitive to touch, taste and equilibrium.

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Maxillae – part of the crayfish mouth that is used to manipulate food

into the mouth where it is chewed by the mandibles. Maxillipeds – three pairs of mouth structures that are sensitive to

touch and taste.

Chelipeds – claw used to capture food and used for defense.

Swimmerets - appendages attached to the anterior five abdominal

segments. - used to create water currents - used in reproduction Uropods - on the sixth abdominal segment, used to help propel the

crayfish during tailflips. Digestion, Respiration, Circulation & Excretion Digestive Gland – secrets enzymes that aid in digestion before the food

enters the intestines. Open Circulatory System – includes dorsal heart, hemolymph & the hemocoel 12

Green Glands – excretory organs that

eliminate excess water from the crayfish.

- needed because that crayfish lives in a hypotonic environment (water is constantly entering the body).

Neural Control Nervous System -similar to annelids -consists of a pair of ganglia above the esophagus &

receive nerve impulses from the eyes. -two bundles of nerve fibers extend from the brain and pass around either side of the esophagus to a ganglia that control the mandibles, maxillae, maxillipeds and then towards the tail. -have sensory hairs all over body but concentrated on antennae region. -compound eyes on movable stalks; each eye has more than 2000 light-sensitive units with their own lenses.

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Subphylum Chelicerata -no antennae -chelicerae present -all appendages are unbranched -four pairs of walking legs -body has two regions (cephalothorax & abdomen) -predominantly terrestrial Class Arachnida -spiders, scorpions, mites & ticks

-terrestrial -book lungs & tracheae for respiration -chelicerae are modified as fangs and used to

inject venom. -numerous eyes (up to eight) each with a single lense

-cephalothorax usually divided into six pairs of lointed appendages: one pair of chelicerae, one pair of pedipalps, which aid in holding food and chewing; and four pairs of walking legs.

Spinnerets – three pairs of organs located on the tip of the

abdomen. - each composed of hundreds of microscopic tubes

that connect to silk glands in the abdomen. - found in spiders

Book Lungs

Book lungs – paired sacs in the abdomen with many parallel folds that resemble the pages of a book.

- the folds provide a larger surface area for gas exchange.

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Tracheae – a system of tubes that carry air directly to the tissues from opening in the exoskeleton known as spiracles.

Malpighian Tubules - hollow projections of the digestive tract

that collect body fluids and wastes and carry them to the intestine.

- help conserve water Coxal Glands – organs that remove wastes and discharge them

through opening at the base of some of the legs in some spiders.

Subphylum Uniramia Class Chilopoda - body flattened & consisting of 15 to 170 or

more segments - one pair of legs attached to each segment - carnivores - centipedes - about 2500 species

Class Diplopoda - elongated body of 15 to 200 segments - two pairs of legs per segment - primarily herbivorous

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- millipedes - about 10,000 species