W11, Arachnids, Insecta
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Describe the basic biology of Chelicerata
• Two main body parts • Cephalothorax • Abdomen • No antennae (can sometimes use to • Six pairs of appendages • Chelicerae (bear the fangs) • Pedipalps • Four pairs of legs • Terrestrial and marine
How do you distinguish between arachnids vs insects? many spiders look like ants as a defence strategy
• # body parts • arachnids have 2 main body parts • insects have 3; a dinstinct head, thorax, and abdomen • Appendages • chelicerae (fangs) and pedipalps • insect mouthparts are highly modified and can look similar, so they’re not a good use for ID • antennae • all insects have antennae • arachnids have no antennae • # pairs of legs • arachnids have four • insects have 3 • wings • arachnids have no wings • insects often have 1 or 2 pairs of wings
What are Aranae?
Spiders
What is it that makes Aranae different from other Arachnids?
Spinnerets (produce silk) on the abdomen
In Aranae, what are the chelicerae commonly known as?
Jaws with piercing fangs
In male Aranae, what are the pedipalps evolved for?
Mating. The male redback has an unusual spiralled pedipalps.
Decribe the eyes of spiders How many do they normally have? Are they simple or compound? Arrangement?
Normally have 8 Eyes are simple - only have one facet Arrangement can be important for ID
What are the pedipalps evolved to be in scorpions?
Pincers
What is the group that mites and ticks are in?
Acari
What is the distinguishing feature of Acari (mites and ticks, if you don’t remember)
Loss of visible body segmentation
What are mites good at controlling, in terms of biological control?
Other mites and thrips.
What are the chelicerae evolved to do in ticks?
To cut skin.
What’s the difference between hard and soft ticks?
Hard ticks • feed once during each stage then leave their host Soft ticks • live in close association with their host • feeds repeatedly during a particular life stage
What are the morphological features that distinguish Hexapoda (and therefore Insecta)?
• The main body sections • head, thorax, abdomen • Antennae • Three pairs of thorasic legs • Hexa = six, poda = foot
What are collembola, what are their biological features, and give an example of one that’s a significant agricultural pest.
Collumbola = springtails • Tubular appendage (collophore) that holds the ‘springtail’ (Furcula) • primarilly detritivores and microbivores • commonly found in leaf litter and other decaying material • highly sensitive to dessication • moult repeatedly during their life, even as adults The lucerne flea is the only pest species of Collumbola • not just lucerne; also canola, field peas, lupins, faba beans • crops are most susceptible following seedling emergence • eggs hatch with soaking autumn rains • 3-5 generations through autumn-spring • diapause eggs laid when conditions get hot and dry
Describe the biology of insects
Antennae Three body parts • head, thorax, abdomen • thorax is divided into three sections, and each section has a pair of legs attached Three pairs of legs Up to two Wings • Evolved as an extension of the cuticle, and thought to be originally for absorbing heat rather than flying • might be difficult to see or evolved to look/ Compound eyes AND up to three simple eyes (ocelli) • Compound eyes made of repeating units Exoskeleton • can have bits of the exoskeleton that is hard and rigid and bits that are flexible Diverse mouthparts Presence of a cercus
What are the three sections that the insect digestive system is broken up into?
Foregut, midgut, hindgut
Describe the respiratory system in insects
Spiracles are openings in the abdomens of insects that draw air in The respiratory system delivers oxygen directly to the cells that need it because the circulatory system is open (i.e. the haemolymph just flows through the body cavity, so if the respiratory system wasn’t closed, the haemolymph would leak out the spiracles).
Describe the difference between gradual (simple, incomplete) and complete metamorphosis
Gradual • Immature stages resemble adults • Only adults have wings and are able to reproduce • Usually feed on the same foods and are found in the same environment during the different stages Complete • Immature stages look nothing like the adults • To go from the larval stage to the adult requires a complete change in morphology • Only adults have wings • Number of instars varies • In many species, the different stages feed on different foods and occupy different niches
What are Blattodea and what are some distinguishing features?
Cockroaches • Oval, flattened body • Head is concealed beneath the pronotum (looks like a shield) • Manibulate (chewing) mouthparts • Antennae • Wing development varies
What are Phasmatodea and what are some distinguishing features?
Stick insects • mimick sticks or leaves • mandibulate mouthparts • all legs adapted for walking • vegetarian • some species are significant pests
What are Orthoptera and what are some distinguishing features?
Grasshoppers, crickets, katydids • hindlegs adapted for jumping (i.e. they’re big and muscley) • filiform antennae (thin) • short = locusts and grasshoppers • long = crickets and katydids • mandibulate mouthparts locusts • form swarms and marching/hopping bands (as nymphs) • once they’re swarming, its too late for control due to their ability to migrate LONG distances very quickly • egg pods can reach densities of 500/m2 • moisture stimulates egg development • eggs laid in autumn enter diapause