1 / 14

Arthropoda

Arthropoda. 5 major lines of arthropod evolution: Trilobitamorpha Cheliceriformes a. Merostomata b. Arachnida Crustacea Hexapoda a. Entognatha b. Insecta Myriapoda. Sub phylum Hexapoda. Diverse group (~1000 families) Twice as diverse as all other animal taxa combined

elysew
Download Presentation

Arthropoda

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Arthropoda 5 major lines of arthropod evolution: • Trilobitamorpha • Cheliceriformes a. Merostomata b. Arachnida • Crustacea • Hexapoda a. Entognatha b. Insecta • Myriapoda

  2. Sub phylum Hexapoda • Diverse group (~1000 families) • Twice as diverse as all other animal taxa combined • Co-evolved with angiosperms • Flower morphology / pollinators • Herbivory / 2°plant compounds/resistance and specialization • Parasitoidism (20% of insects are parasitoids)

  3. Hexapoda • Mostly terrestrial • In every habitat except the subtidal marine habitat – competition from crustacea? • 3 tagma: head, thorax, abdomen • 3 pairs of legs, and usually 2 pairs of wings on thorax • no abdominal appendages

  4. Major contributors to insect success Arthropod body plan • Small size • Resistance to desiccation • Trachea • Waterproof cuticle, egg shell • Malphigian tubules • Flight • Rapid dispersal • Escape from predators • Access to distant food, mates • Holometaboly: • Larvae and adults occupy separate niches (most speciose groups are all holometabolous: coleoptera, lepidoptera, hymenoptera, diptera)

  5. Holometabula • Hemimetabolous development • e.g. Odonata, Orthoptera, Blattodea • Mantodea, Hemipteroids • Incomplete metamorphosis • Wing pads present in pre-adult • Larvae often resemble small adults • Holometabolous development • e.g. coleoptera, lepidoptera, diptera, hymenoptera • Complete metamorphosis • Inactive pupal stage • Larvae do not • resemble parents • eat the same things as parents • live in the same habitat as parents

  6. Big picture • Hugely important ecologically as pollinators (2/3 of all flowering plants), detritivores, herbivores • Important economically and socially (to humans) as disease vectors (fleas, lice, bedbugs, biting flies), crop pests (and also as pollinators and biological control agents)

  7. Hexapoda 2 classes: • Entognatha (mouth parts recessed), • Insecta (mouthparts are ectognathous = exposed and projecting from head capsule)

  8. Hexapod origins • From aquatic crustacean ancestor • Probably freshwater • Winglessness (apterygota) is primitive condition

  9. “Pterygota” • Flight evolved 300-400 mya • Wings = outpocketings of exoskeleton • Origins of wings? Multiple hypotheses: • Used for thermoregulatory purposes then later co-opted for flight? • Used to stabilize body during jumping? • Modified from external gills? (genetic similarities with crustacean gill structures)

  10. Requirements for flight • Musculature • Striated • Attached to strong exoskeleton with flexible joints • Small body size • Impervious to water loss • Efficient internal physiology for gas exchange (trachea), nutrient storage and distribution • Well-developed and integrated sensory organs to regulate rapid movement

  11. Low rate of wing-flapping • Odonata, ephemeroptera, orthoptera, lepidoptera • Flapping rate limited by firing rate of neurons • High rate of wing-flapping • Diptera, hymenoptera, coleoptera • Use elastico-mechanical properties of exoskeleton to stimulate stretch receptors to produce self-sustaining flight

More Related