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28-1 Introduction to Arthropods

28-1 Introduction to Arthropods. Video 1. I. Form and Function in Arthropods A. All arthropods have 3 key features: 1. Tough exoskeleton 2. Jointed appendages 3. Segmented body. Many arthropods have 3 additional features: 1. Brain in the dorsal part of the head

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28-1 Introduction to Arthropods

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  1. 28-1 Introduction to Arthropods Video 1

  2. I. Form and Function in Arthropods A. All arthropods have 3 key features: 1. Tough exoskeleton 2. Jointed appendages 3. Segmented body

  3. Many arthropods have 3 additional features: • 1. Brain in the dorsal part of the head • 2. Ventral nerve cord • 3. Open circulatory system with a heart

  4. Arthropod body plan • 1. Exoskeleton: A system of external supporting structures that are made of carbohydrate chitin • a) Function: • i) Protection • ii) Waterproof (prevents water loss) • iii) Move efficiently b) Disadvantage: Skeleton cannot grow as the animal grows

  5. D. Feeding • List and give an example of each type of feeding method • Herbivores – locusts • Carnivores - spiders, centipedes • Parasites - ticks, fleas, lice • d) Filter feeders - marine arthropods • (barnacles) • e) Detritus feeders - crayfish

  6. E. Respiration 1. 3 basic types of respiratory structures: a) Gills b) Book gills and book lungs c) Tracheal tubes • F. Internal Transport • Have a well-developed heart pumping blood through an opencirculatory system. • Blood moves out of heart moves through spaces called sinuses.

  7. G. Excretion 1. Solid waste: Leaves through the anus 2. Metabolic waste eliminated by: a)Malphighian tubules - filter nitrogen based waste from blood b)Diffusion through the gills c) Green glands - filter blood at base of antennae

  8. H. Response 1. Nervous system composed of: a) Brain (with 2 ganglia in the head) b) A pair of nerves that runs around the esophagus and connects the brain to a ventral nerve cord

  9. 2. Have sense organs such as: a) Statocysts b) Chemical receptors c) Compound eyes d) Taste receptors e) Sensory hairs f) Ears

  10. 3. Defense against predators: • Venomous stings and bites • Attack with powerful claws, chemicals • Create a diversion (ex. Drop a body part) d) Visual trickery (ex. camouflage)

  11. I. Reproduction 1. Fertilization is internal 2. Males transfer sperm directly or drop a packet of sperm that is picked up by the female Cockroaches

  12. II. Growth and Development in Arthropods A. What is a problem with exoskeletons? They must be replaced with larger ones in order to allow the body inside to increase in size as it matures B. Describe the steps that occur during molting: 1. The epidermis digests the inner part of the exoskeleton, absorbing the chitin to recycle it 2. Secretes a new exoskeleton inside the old one

  13. 3. Arthropod pulls completely out of its old exoskeleton (may eat what’s left – more recycling) 4. The animal then expands to its new, larger size, and the new exoskeleton stretches to cover it 5. Wait for the new exoskeleton to harden; during these few hours to a few days, the new shell is soft and the animal is quite vulnerable Giant Spider Crab Molt

  14. C. What is the difference between complete metamorphosis and incomplete metamorphosis? • Complete Metamorphosis involves VERY different physical appearances at the different stages of growth (usually: egg, larva, pupa, adult). Butterfly LifeCycle • Incomplete Metamorphosis is involves stages with a physical appearance that more closely resembles one another (usually: egg, nymph, adult). Preying Mantis Lifecycle

  15. 28-2 Spiders and Their Relatives I. Spiders and Their Relatives Video 2 A. Subphylum Chelicerata has 3 main characteristics 1. Two-part body 2. Mouthparts called chelicerae 3. Lack sensory “feelers” (antennae) on the head

  16. II. Arachnids A. Characteristics: 1. Four pairs of walking legs on their cephalothorax 2. Carnivores that have pedipalps adapted for capturing and holding prey and chelicerae adapted for biting and sucking out their soft parts

  17. B. Some examples of Arachnids: 1. Spiders 2. Mites and ticks 3. Scorpions

  18. C. Spiders 1. Diet: Insects a. Describe how a spider eats. - It uses its hollow fingerlike chelicerae to inject paralyzing venom into it. - When the prey is paralyzed, it introduces enzymes which break down the tissues into the wounds made by the chelicerae. - It sucks up the liquefied tissues with its esophagus and specialized pumping stomach.

  19. 2. Silk: strong, flexible protein a. Why do arachnids build silk structures? Produce webs for catching food, cocoons for eggs, wrappings for prey

  20. 28-3 Crustaceans • Crustaceans Size: 0.25 mm to 6 m A. Characteristics: 1. Hard exoskeleton 2. Two pairs of antennae 3. Mouthparts called mandibles • Christmas Island

  21. C. The 3 body parts are called: 1. Head 2. Thorax 3. Abdomen D. Cephalothorax: Head and thorax fused

  22. E. First two pairs of appendages are for: 1. Sensing 2. Filter feeding 3. Moving F. Third pair of appendages are mouthparts called mandibles for: 1. Biting and grinding food 2. Filter feeding 3. Finding and picking up detritus

  23. G. The appendages on the thorax and abdomen can be for: 1. Filter feeding 2. Legs for walking or paddles for swimming 3. Internal fertilization 4. Carrying eggs 5. Spearing prey 6. Burrowing The Mantis Shrimp! The Mantis Shrimp!!

  24. 28-4 Insects & Their Relatives I. Insects and Their Relatives A. Characteristics: 1. One pair of antennae 2. Appendages that do not branch VIDEO B. Habitat: terrestrial, fresh and salt water

  25. II. Centipedes and Millipedes A. Centipedes 1. Description: Long, wormlike body; 1 leg/segment 2. Lifestyle = predator or carnivore B. Millipedes 1. Description: Long, wormlike body; 2 legs/segment 2. Lifestyle = decomposer or herbivore

  26. III. Insects A. Characteristics: 1. Body divided into 3 parts(head, thorax, abdomen) B. Feeding 1. Why are the mouthparts so different in different insects? They feed on a large variety of foods 2. Saliva contains specialized enzymes: a) Helps break downfood b) Prevents blood from clotting (mosquitos) c) Change nectar into honey (bees)

  27. C. Movement 1. Walk/jump 2. Fly D. Insect societies 1. Society: Separate individuals that depend on one another for survival Video & Ted-Ed Video 2. Within societies, there is division of laborVideo

  28. 3. The 3 basic castes & their main function(s) are: a) Reproductive females (queens) – lay eggs b) Reproductive males – fertilize the eggs c) Workers – perform all non- reproductive tasks (care for eggs, gather food, build, maintain, and defend the colony’s home)

  29. E. Insect communication 1. Use: a) Sound eg. cockroaches b) Visual signals eg. firefly c) Chemical signals eg. stinkbug

  30. 2. Functions of communication are: a) Finding a mate b) Convey information to members of the colony 3. Pheromone: specific chemical messenger that affects the behavior and/or development of other individuals of the same species

  31. 28-5 How Arthropods Fit into the World I. How Arthropods Fit into the World A. Ecological role: 1. Sources of food Video 2. Pollinate plants Ted-Ed Vid B. Contributions to human life: 1. Produce products (ex. Honey, silk) 2. Medicalandscientificresearch

  32. C. List 3 things that arthropods damage: 1. Crops 2. Livestock 3. Property (structures, clothes, etc)

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