BIOL 305 — Arthropoda
Arthropoda
- Crustaceans, Insects
- Various Orders
- Coleoptera — Beetles
- Diptera — Flies
- Orthoptera — Crickets, Grasshoppers
- Lepidoptera — Moths
- Blattodea — Cockroaches
- Odonata — Dragonflies
- Hymenoptera — Ants, Bees, Wasps
- Insects make up 75% extant species; other arthropods make up 11%
- 900,000 species; 400,000 are beetles
Shared Characteristics
- Jointed segmentation: Head, thorax, abdomen
- Paired, jointed appendages
- Armor-like exoskeleton
- Open circulatory system with a dorsal tubular heart and aorta with ostia
Ecdysis and Exuviae
Ecydsis
- Molting
- The exoskeleton cuticle is molted and shed
- Soft-bodied, increased fluids increase size before hardening
Exuviae
- The remnants of the exoskeleton that were shed in ecydsis
Subphyla
| Phylum, Synapomorphy | Chelicerata | Crustacea | Hexapoda | Myriapoda |
|---|---|---|---|---|
| Segmentation | Two | Two, named | Three | Two, named |
| Legs | Four | Five or more | Six | Two per segment |
| Antennae | None | Two | Two | One |
| Synapomorphy | Chelicerae | Biramy | Multi-segmented antennae |
Chelicerata
- Horseshoe crabs, spiders, scorpions, ticks, mites
- Two major body segments
- No antennae
- Chelicerae: Pincers/Fangs
- Chelicerae are the first pair of appendages near the mouth; may be claw-like
- Palps/Pedipalps
- 2nd pair of appendages; multi-use
- Raptorial, manipulative, sensory; digs burrows or transfers sperm
- Four pairs of legs used for sensory, communication, fighting in courtship, movement
Arachnida
- Sea spiders, spiders, scorpions, ticks, pseudoscorpions, horseshoe crabs, mites, ticks, opilones/harvestmen, solifuges (camel/sun spiders)
- Mostly terrestrial
- Eight legs
- Chelicerae: Pre-oral jaws
- One pair of pedipalps
Crustacea
- Crabs, lobsters, crayfish, shrimp, krill, woodlice, barnacles
- Two major body segments: cephalothorax and abdomen
- Two pairs of antennae
- Biramous; two-part limbs
- Mostly aquatic; exclusions such as pill bug and sow bug
- Breathe using gills
- 5 or more pairs of legs
Hexapoda
- Six legs in adulthood
- Beetles, bugs, flies, wasps, ants, grasshoppers
- Three major body segments
- One pair of antennae
Insecta
- Over 90% of known terrestrial arthropods are insects
- More than half of known species are insects
- Hyperdiverse
- Three body regions, one pair of antennae, three pairs of legs in adulthood, and two, one, or no pairs of wings
- Undergoes metamorphosis
- Incomplete metamorphosis: Juveniles resemble adulthoods but do not have wings
- Complete metamorphosis: Juveniles do not resemble adulthoods
- Four distinct life stages: Egg, larvae, pupa, adult
- Worm-like larvae with different stages of development
- Resource partitioning
| Order, Synapomorphy | Coleoptera | Orthoptera | Blattodea | Lepidoptera | Diptera | Odonata | Hymenoptera |
|---|---|---|---|---|---|---|---|
| Mouthpart Specialization | Chewing | Chewing | Chewing | Chewing or Sucking | Biting, Sucking, or Absorbing | Chewing | Chewing |
| Predation | Herbivores, Detritivores, Omnivores | Herbivores | Omnivores | Herbivores or Nectivores | Carnivores, Detritivores, Nectivores | Carnivores | Carnivores, Detritivores, Nectivores |
| Fore Wings | Elytra sheath | Yes | Yes | Scaled | Flight wings | Yes | Yes |
| Hind Wings | Sheathed flight | Yes | Yes | Scaled | Haltiers | Yes | Yes |
| Metamorphosis | Complete | Incomplete | Incomplete | Complete | Complete | Incomplete | Complete |
| Disease Vectors | Mosquitoes, Tsetse |
Coleoptera
- Beetles
- Nearly half of all insects
- Mouthparts specialized for chewing
- Herbivores, detritivores, predators
- Two pairs of sheathed wings: front wings were hardened for protection called elytra
- Complete metamorphosis
Orthoptera
- Grasshoppers, crickets, katydids
- Two pairs of wings
- Mouthparts specialized for chewing
- Herbivores
- Incomplete metamorphosis
Blattodea
- Cockroaches and termites
- Former termites: Isoptera
- Two pairs of wings
- Mouthparts specialized for chewing
- Omnivorous
- Incomplete metamorphosis
Lepidoptera
- Moths
- Two pairs of wings; scaled wings
- Mouthparts specialized for sucking
- Herbivorous as larvae; nectar-feeding as adults
- Complete metamorphosis
Diptera
- Flies
- One pair of flying wings and one pair of hind wings: haltiers
- Weights at end of hind wings provide counterbalance that allows them to fly straight
- Mouthparts specialized for biting, sucking, or absorbing
- Carnivorous, detritivores, nectar-feeding
- Complete metamorphosis
Odonata
- Dragonflies and damselflies
- Two pairs of flight wings
- Mouthparts specialized for chewing
- Carnivorous
- Large eyes
- Predators
- Diurnal fliers
- Incomplete metamorphosis
Hymenoptera
- Bees, ants, wasps
- Hyperdiverse
- Various social characteristics
- Two or no pairs of wings
- Mouthparts specialized for chewing
- Carnivorous, herbivorous, nectar/pollen-feeding
- Complete metamorphosis
Myriapoda
- Many legs in adulthood
- Millipedes, centipedes, symphyla
- Two major body segments: head and multi-segmented antennae
- One pair of antennae
Chilopoda
- Centipedes
- Flattened body
- One pair of legs for each segment
- Venomous bite
Diplopoda
- Millipedes
- Rounded body
- One pair of legs for each segment
- Poisonous, but not venomous
Disease Vectors
Ticks
- Arthropoda Chelicerata Arachnida
- Two diseases:
- Rickettsia bacterium — Rocky Mountain Spotted Fever
- Borrelia spirochete — Lyme disease
Lice
- Arthropoda Hexapoda Insecta
- Body louse
- Rickettsia bacterium — Epidemic typhus
Fleas
- Arthropoda Hexapoda Insecta Siphonaptera
- Yersinia bacterium — Plague
Mosquitoes
- Arthropoda Hexapoda Insecta Diptera
- Three viruses
- West Nile
- Dengue
- Chikungunya
- World’s deadliest animals; 725,000 kill humans due to vectors vs. 475000 killed by other humans
- Climate change affecting spread of disease
- Also Zika, Malaria, Elephantiasis, Yellow Fever
Tsetse Flies
- Arthropoda Hexapoda Insecta Diptera
- Trypanosoma protozoan — Sleeping sickness