Field Cricket

After completing this section students should be able to:


Terms: hearts, aorta, ostia, plasma, hemolymph, spiracle, trachea, taenida, respiratory plastron, fat body, peritrophic membrane, foregut, midgut, hindgut, brain, synapse, protocerebrum, tritocerebrum, deutocerebrum, subesophageal ganglion, ventral nerve cord, malpighian tubules, ecdysis, metamorphosis, juvenile hormone, ecdysone, brain hormone, oviparous, viviparous, ovoviviparous, spermatheca, spermatophore, parthenogensis, hermaphrodite.

A. Internal Anatomy Structure.

    1. Circulation.

        a. Organization.

            (1) Humans--closed.
            (2) Insects--open.

        b. Structures.

            (1) Hearts--Ostia.
            (2) Aorta.

        c. Efficiency.

        d. Functions.

            (1) Transport.
            (2) Protection.
            (3) Hydraulic.
            (4) Respiration (minor).
            (5) Thermoregulation.

        e. Blood characteristics.

            (1) Color.
            (2) Contents.

    2. Digestive system.

        a. Foregut (exoskeletal).

            (1) Conducts, stores, guides foods.

        b. Midgut (mesodermal).

            (1) Major absorption.
            (2) Enzyme production.

        c. Hindgut (exoskeletal).

            (1) Transports waste from body.
            (2) Reabsorbs water, salt.

        d. Salivary glands.

            (1) Food solvent.
            (2) Digestive enzymes.
            (3) Produce glue, silk (saliva, of course).

        e. Digestive process.

            (1) Intestinal.
            (2) Extra-intestinal.
            (3) Microbial aids.

    3. Excretory System.

        a. Function: Maintain environment suitable for survival.
            (1) Elimination of waste.
            (2) Regulation of salt and water.

        b. Malpighian tubules.

        c. Hind gut.

    4. Ventilation.

        a. Tracheal System.

            (1) Spiracles.
            (2) Tracheae.
            (3) Air sacs.
            (4) Taenida.

        b. Mode of action.

            (1) Diffusion.
            (2) Pumps.

        c. Efficiency.

            (1) Aquatic Adaptations for Respiration.

    5. Nervous System. Brain and ventral nerve cord.

        a. Brain

            (1) Role: Receive, integrate sensory data (little coordination).
                • Protocerebrum.
                • Deutocerebrum.
                • Tritocerebrum.

        b. Ventral nerve cord and ganglia.

            (1) Subesophageal ganglia.
            (2) Thoracic ganglia.
            (3) Abdominal ganglia.

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Section IV Continued

B. Life Support Systems

    1. Growth

        a. Exoskeleton limits growth.

        b. Shedding exoskeleton (ecdysis) necessary.

        c. Ecdysis involves loss of:

            (1) Outside body covering.
            (2) Foregut
            (3) Hindgut
            (4) Respiratory system.

    2. Metamorphosis. Regulated by juvenile hormone and Ecdysone.

        a. Types of Metamorphosis.

            (1) Simple, (silverfish). Ametabola
            (2) Gradual ( grasshoppers.) Paurametabola
            (3) Complete ( flies.) Holometabola

    3. Reproduction. Insects sexual structures:
        Males:    Females:
        testis    ovaries
        vas deferens    ovarioles
        seminal vesicle    spermatheca
        accessory glands    spermatheca gland
        penis (adaegus)    oviduct
        spermatophore    vagina


        Eggs deposited at various stages.

           • Oviparous (most insects) lay undeveloped eggs.
           • Ovoviparous ( aphids) eggs develop and hatch inside female, escape
           • Viviparous (Tsetse flies) egg hatches inside female, nourished by
              pseudoplacenta, or on female.

        Exceptions to normal reproduction.
           • Parthenogenesis,
           • Hermaphrodism

  1. What are the basic structures of the insect respiratory system. Compare those structures to the ones found in the human respiratory system.
  2. What is the role of the insect circulatory system in respiration?
  3. List the components of the insect circulatory system. How does its' efficiency compare to that of humans?
  4. What are the basic structures of the insect excretory system? What would you call the insect "liver"?
  5. What is the basic function of the insect "brain"? Why doesn't an insect die immediately when you cut off its head?
  6. What part of the insect nervous system do you think controls the courtship behavior?
  7. What insect hormone cause the molting process to be initiated?
  8. What is the technical name of the "molting" hormone?
  9. What is parthenogenetic reproduction? Name one insect group that uses this approach.
  10. What is the function of the spermatheca? In what sex is it found?

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