The document summarizes the characteristics of the phylum Arthropoda. It describes their key features such as an exoskeleton made of chitin, segmented bodies, and jointed appendages. The four major subphyla are described as Trilobita, Chelicerata, Crustacea, and Uniramia. Arthropods make up over 2/3 of animal species and are highly adapted to live on land and in water.

1. Arthropoda

2. Core Concept Exoskeleton= chitin Jointed appendage Segmented body brain- dorsal part of the head Ventral nerve cord Open circuatory system, single heart

3. Body plan- adaptation for low water loss Found in all types of habitat

4. Four major subphyla Trilobita (fossilized trilobites) Chelicerata (spiders, ticks, mites, scorpions, horseshoe crabs) Crustacea (crabs, craysfish, shrimps, barnacles, pill bugs, water fleas) Uniramia (centipedes, millipedes,, all insects) Class Chilopoda (centipede) Class Diplopoda (millipedes) Insecta

5. Keywords Arthropoda Trilobita Chelicerata Crustacea Uniramia Chilopoda Diplopoda Insecta Molting Metamorphosis:complete/incomplete Hemolymph hemocoel ventral nerve cord Head thorax abdomen cephalotorax Carapace chelicerae malpighian tubules Green gland book gills book lungs Spiracles tracheal tubes

6. Characteristics 2 out of 3 organisms are arthropods Segments: head, thorax, abdomen Fused segments: cephalotorax Extensive cephalization Open circulatory system: use of hemolymph and hemocoels Exoskeleton: prevents water loss, attachment of muscle

7. Exoskeleton- limits growth Molting- allows growth (energy expensive) Bases for subdivision of phylum- number of antenna, presence or absence of jawlike mandibles, type of appendages *Crustaceans and insects may be more closely related

8. Digestive system Complete gut Every mode of feeding

9. Respiratory system Gills- aquatic Book gills- horseshoe crab Book lungs Tracheal tubes w/ spiracles

10. Circulatory System Well-developed heart Open circulatory system Hemolymph –blood + interstitial fluid Sinus- space that surrounds organs Hemocoel collective term

11. Excretory system Malpighian tubule- remove nitrogenous waste from blood Gills Green glands- found beneath the antenna, remove nitrogenous waste

12. Nervous system Brain- made up of pair of ganglia Ventral nerve cord- presence of ganglia per segment Simple and complex sense organs Statocysts- balance Compound eye- ommatidium of fly

13. Reproductive system Internal fertilization Some have queens

14. Subphylum Trilobita Oldest subphylum Extinct Three lengthwise lobes from head to tail One pair of unspecialized appendages per body segment Appendage divided into two branches Gill Walking leg

15. Subphylum Chelicerata Cheilos- lips; cheir- arm Chelicerae- clawlike feeding appendage Arachnids- chelicerae are called pedipalps 4 pairs of walking legs 2 fused segments- cephalothorax, abdomen Lack antenna

16. Subphylum Crustacea Mostly aquatic and marine 2 pairs of antenna Mouth parts are called mandibles 2 branches of appendages Many have carapace

17. Subphylum Uniramia Almost all are terrestrial 1 pair of antenna Have mandibles Unbranched appendages

18. Class Chilopoda Centipedes Long, worm-like body Many segments One pair/ segment Poison claw for feeding carnivorous

19. Class Diplopoda Wormlike bodies with many segments 2 pairs of legs per segment Mostly herbivorous

20. Class Insecta Insects Body parts- head, thorax, abdomen Three pairs of legs Usually two pairs of wings attach to thorax Metamorphosis: complete/incomplete