Phylum Arthropoda: Jointed Foot

Importance

-8 out of 10 animals are arthropods

-invaded every known ecosystem

-reproduce by the millions

-millions spent eliminating them

Taxonomy and Organization

Phylum Arthropoda

Subphylum Trilobita

Subphylum Chelicerata

-Class Merostomata

-Class Arachnida

Subphylum Crustacea

-Class Cirripedia-Class

Malacostraca

Subphylum Uniramia-Class Insecta

-Class Diplopoda-Class Chilopoda

Arthropod Characteristics

1. Exoskeleton: made of chitin

-Molting: shedding the exoskeleton

2. Segmentation: head, thorax, abdomen (tagmatization)

3. Paired and jointed appendages

4. Metamorphosis – changing of the body forms throughout life cycle

5. Well developed sensory organs

-compound eyes-antennae-pheromones

6. Prolific reproduction: short life span + high reproduction = rapid evolution

7. Complex behaviors and social interactions

Subphylum Trilobita: The trilobites

-first arthropods-dominant in the Paleozoic

Era-all extinct-no known ancestry

Subphylum Chelicerata: 2 Classes

Class Merostomata: horseshoe crabs

Class Merostomata: horseshoe crabs

-circular shaped exoskeleton

-five pairs of walking legs-small pair of chelicera

(pinchers)-telson: long, triangular

spiked tail-blue blood, used to test

commercial drug purity

Class Arachnida: scorpions, spiders, mites, and ticks

-cephalothorax: head and thorax combined

-chelicera: fangs found in arachnids

-pedipalp: specialized feeding appendages

-book lungs: specialized respiratory organs

-ticks: blood sucking parasites; cause Lyme’s disease and Rocky Mt. Spotted fever

-scorpions: the oldest known terrestrial arthropods

Specimens:

-black widow spider-black and yellow argiope-brown recluse-wolf spider-rose hair tarantula-mexican white-kneed

tarantula-wood tick-emperor scorpion-desert scorpion

Subphylum Crustacea: 2 Classes

Class Cirripedia: barnacles

-adults are sessile; attach to whales, rocks, wood

-protected by a calcareous shell

-cirri: appendages used to gather food

Specimens: giant barnacles, goose necked barnacle

Class Malacostraca: crabs, lobsters, crayfish, and shrimp

-ten walking legs-mostly marine-sexes are separate-open circulatory system

Specimens:

-Blue crab-hermit crab-emerald crab-marsh crab-reef lobster-crayfish-fiddler crab

Subphylum Uniramia: 3 Classes

Class Chilopoda

-arthropods with segmented, elongated bodies

-one pair of legs per body segment

Ex. Centipedes

Class Diplopoda

-two pairs of legs per body segments

Class Insecta: Entomology: the study of insects

-75% of all animal biodiversity are insects

-biologists estimate that only 1/50th have been identified

Characteristics:

1. Three body segments

2. Three pairs of legs

3. One pair of antennae

4. Most have two pairs of wings – key to their success

5. Metamorphic life cycle

Negative Impact of Insects

1. Pests/tormentors: flies, gnats, mosquitoes

2. Disease vectors: mosquitoes, flies

3. Agricultural damage: crops and food

4. Property Damage: termites and ants

Positive Impacts of Insects

1. Plant Pollinators: mutualistic relationship. 65% of all plants are pollinated by insects

2. Ecological Importance: foundation of the food web

3. Economic Impact: honey, wax, dye, biodiversity

Insect Orders: most end in “ptera” - wing

Order Lepidoptera: “scale wing”

-insects with two pairs of wings covered by colorful scales

-moths and butterfliesEx. Monarch butterfly,

polyphemus moth, luna moth, underwing moth

Order Coleoptera: “sheath wing”

-insects with a hardened pair of forewings

-the beetlesEx. Colarado potato

beetle, stag beetle, June beetle, Japanese beetle

Order Hymenoptera: “membrane wing”

-insects with two pairs of transparent wings

-most carry toxins in their stinger

Ex. Honey bee, bald-faced hornet

Order Orthoptera: “straight wing”

-insects with straight wings

Ex. Differential grasshopper, lubber grasshopper, red-legged grasshoppers

Order Diptera – “two wings”

-insects with one pair of transparent wings

Ex. Horsefly

Order Odonata: “toothed”

-predatory insects with large mandibles and two pairs of transparent wings

Ex. Green darner