Arthropods/Arachnids/ Crustaceans/Insects 1

What is an Arthropod? 1. Invertebrates 2. Characteristics: A. Jointed appendages:  allows for varied movement B. Segmented bodies:  head, thorax, abdomen or cephalothorax: –fused head & thorax C. Exoskeletons:  hard, outer covering that must be molted (shed) 2

D. Well-developed nervous system E. Coelomates F. Bilateral Symmetry G. Efficient Gas Exchange H. Acute senses: –Includes antennae, compound & simple eyes, pheromones I. Complex body systems J. Sexual reproduction: –Internal fertilization if terrestrial –External fertilization if aquatic –Some are hermaphrodites 3

Which Animals are Arthropods? Arachnids: Arachnids: –spiders –ticks –mites –scorpions Crustaceans: Crustaceans: –crabs –lobsters –crayfish –shrimp Insects: Insects: –beetles –butterflies & moths –praying mantis 4

Arachnids 1. Two body segments: A. Cephalothorax B. Abdomen 2. 6 pairs of appendages: A. Chelicerae: near mouth, modified as pincers or fangs B. Pedipalps: near mouth, adapted for handling food & sensing 3. 4 pairs of walking legs 5

Spiders 1. All are poisonous: paralyze prey 2. Two may be fatal to humans: Brown RecluseBrown Recluse Black WidowBlack Widow Simple Eyes One lens per eyeOne lens per eye Better for sensing imagesBetter for sensing images 4. Book lungs for oxygen exchange: air filled chambers 5. No mandibles: Must liquify food before eatingMust liquify food before eating 6. No antennae 6

7. All produce silk in silk glands Not all form websNot all form webs 8. Spinnerets: form silk into strands 9. Reproduction: sexual, separate sexes 10. Male’s pedipalps carry sperm to female 11. Eggs are fertilized & wrapped in cocoon called egg sack 12. Females are usually larger than males 13. She usually attacks him after mating 7

AbdomenCephalothorax Book Lung Eyes Brain Pumping stomach Heart Intestine Ovary Malpighian tubules Anus Spinnerets Silk glands Spiracle Bases of walking legs Fanglike chelicera Pedipalp Poison gland Airflow Anatomy of a Spider Anatomy of a Spider 8

Other Arachnids 1. Mites: 1 body segment often microscopic1 body segment often microscopic parasites on mammalsparasites on mammals 2. Ticks: 1 body segment1 body segment feed on bloodfeed on blood can carry diseasescan carry diseases 3. Scorpions: enlarged pincers to hold preyenlarged pincers to hold prey poison gland located on tailpoison gland located on tail 9

Crustaceans 1. Mostly aquatic 2. Feathery gills for gas exchange 3. Mandibles adapted for crushing food 4. Predators or scavengers 5. Two pairs of antennae to aid in sensing 6. Two compound eyes Contain many lensesContain many lenses Usually on stalksUsually on stalks Better to see motionBetter to see motion 10

7. May have two or three body sections 8. Sexual Reproduction: Separate sexesSeparate sexes 9. Small ganglion in anterior region Nerve cord carries impulses through bodyNerve cord carries impulses through body 10. Muscles allow for movement many found in tailmany found in tail 11. Chelipeds: pincers 12. Walking Legs 13. Swimmerets: underside of tail, used for swimming,& sex determination 11

Millipedes & Centipedes 1. Centipedes (Class: chilopoda) a. Carnivores a. Carnivores b. Bite with pincers, inject poison b. Bite with pincers, inject poison c. Live under rocks, dead leaves c. Live under rocks, dead leaves d. Flattened bodies which may have bright colors d. Flattened bodies which may have bright colors 2. Millipedes (Class: diplopoda) a. Eat plants, dead matter a. Eat plants, dead matter b. Don’t bite, but can spray fluid from stink glands b. Don’t bite, but can spray fluid from stink glands c. Live on damp forest floor c. Live on damp forest floor d. Rounded bodies which are usually dull in color d. Rounded bodies which are usually dull in color 12

Quiz : Arthropods 1. Which of the following is not an arachnid? a. shrimp b. scorpion c. spider a. shrimp b. scorpion c. spider 2. All spiders ___ poisonous. a. are b. are not a. are b. are not 3. What do crustaceans use for gas exchange? a. book lungs b. gills c. tracheal tubes a. book lungs b. gills c. tracheal tubes 4. What structure do crustaceans use as pinchers? a. chelipeds b. swimmerets c. telsons a. chelipeds b. swimmerets c. telsons 5. Which of the following is NOT a difference between millipedes & centipedes? a. centipedes are carnivores, millipedes are herbivores a. centipedes are carnivores, millipedes are herbivores b. centipedes have more legs than millipedes b. centipedes have more legs than millipedes c. centipedes have poison, millipedes stink glands c. centipedes have poison, millipedes stink glands 13

Class Insecta Ex: butterflies, beetles, bees, flies Entomologist – person who studies insects Entomologist – person who studies insects General Characteristics of Insects General Characteristics of Insects 1. Largest group of Arthropods & most diverse group of animals 2. Three body regions: head, thorax abdomen 3. Three pairs of legs (6 total) 4. One pair of antennae - sense vibration & food antennae

5. Eyes: a) at least one pair of compound eyes b) usually 2 compound eyes & 3 simple eyes Simple eyes Compound eyes mandibles

6. Sensory hairs – cover antennae & exoskeleton and are sensitive to movement & touch 7. Spiracles – holes in the abdomen that allow oxygen to enter 8. Tracheal tubes – air from spiracles enters these tubes and circulates through the body (exchanging O and CO ) 9. Tympanum – flat membrane used for hearing, located on used for hearing, located on the ventral side near thorax the ventral side near thorax 22

10. Wings a. Some insects have 2 sets of wings, used for escaping predators, finding mates, food, and new places to live. b. Only invertebrates that can fly wings

Specialized Mouthparts: a.Piercing mouthparts – feed by inserting tube- like mouth into food; usually to suck blood Ex: mosquito b.Sucking mouthparts – feed by unrolling tube- like mouth to reach nectar inside of flowers Ex: butterfly Ex: butterfly

c.Sponging mouthparts – feed by lapping up food after secreting enzymes to digest food Ex: flies d.Chewing mouthparts – feed by biting and chewing on food Ex: Beetles

12. Reproduction a. Sexually, separate sexes b. Internal fertilization; female then lays many shelled eggs (large # of eggs  better change of survival) (large # of eggs  better change of survival) c. Usually mate infrequently or only once d. Mate only in adult stage of metamorphosis 13. Circulation – open circulation

14. Defense A. secrete foul-smelling chemicals Ex: roaches, stinkbugs B. poisonous stings: Ex: wasps, bees, some ants C. mimicry: similarity in appearance 1. Insects with similar defense look alike, predators learn to avoid them 2. Insects with no defense mimic appearance of stinging or bad tasting insects D. camouflage: blending into surroundings

15. Social Behavior of Insects A. Division of labor : 1. individual performs different tasks for colony Examples: termites, ants, some bees and wasps 2. Examples: a. termite colony: workers, soldiers, 1 king & queen to produce young

b. ant colony: 2 or more queens, reproductive males, worker females c. Bees: 1 queen, few males, female workers

B. Communication : chemicals, visual signals, motions 1. pheromones: chemicals that influence behavior a. Attract mates b. Mark trails 2. visual signals: a. Attract mates by flashing light(fireflies) 3. motions: a. Courtship rituals b. Forager bees find nectar, return to hive, performs “waggle” dance to indicate to others direction & distance of food

16. Two Insect Life Cycles A. Complete Metamorphosis ** the insect changes completely through four life stages; controlled by internal chemicals 1.Egg- beginning of life 2.Larva- (caterpillar) free-living wormlike stage A. will molt several times B. grows rapidly C. eats constantly to store food for next stage

3. Pupa - (cocoon) period of reorganization where: A. tissues & organs are reorganized B. some tissues are replaced with adult tissues(reproductive organs) 4. Adult - emerges from pupa: sexually mature

B. Incomplete Metamorphosis * The immature stage looks like mature stage of insect, 3 stages 1.Egg - surrounded by protective shell that contains nutritious food for offspring 2.Nymph - hatches from egg A. does not have fully developed appendages B. does not have reproductive system 3.Adult - occurs after nymph molts several times A. has fully developed appendages(wings) B. has reproductive organs.

Quiz 7 1. __ is a person who studies insects. a. Herbitologist b. Virologist c. Entemologist 2. Insects have 2 __ eyes and 3 simple eyes. a.large b. compoundc. complex 3. ? are holes in the abdomen that allow air to enter. a.Spiracles b. Tracheal c. Tympanum 4. Which of the following are specialized mouthparts? a. Sucking b. Chewing c. Sponging d. Piercing d. ALL 5. ____ is a similarity in appearance. a. Mimicry b. Camaflouge c. Pheromones

Quiz 7 1. __ is a person who studies insects. a. Herbitologist b. Virologist c. Entemologist 2. Insects have 2 __ eyes and 3 simple eyes. a.large b. compoundc. complex 3. ? are holes in the abdomen that allow air to enter. a.Spiracles b. Tracheal c. Tympanum 4. Which of the following are specialized mouthparts? a. Sucking b. Chewing c. Sponging d. Piercing d. ALL 5. ____ is a similarity in appearance. a. Mimicry b. Camaflouge c. Pheromones