1. Chapter 38
Arthropods
Subphylum: Crustacea

2. Characteristics Arthropods have three main characteristics:
A tough exoskeleton, made of chitin
Jointed appendages
A segmented body

3. Subphylum Crustacea Contains over 40,000 species
Crustaceans are abundant in oceans, lakes, and rivers
Some crustaceans are
Sessile (no movement)
move by walking on legs
swimming with paddle like appendages
Drift with currents

4. Crustaceans
Includes shrimp, lobsters, crayfish, barnacles, isopods, copepods, and water fleas.

5. External Structure 2 Major Sections: Cephalothorax:
Head with 5 segments
Thorax with 8 segments
Fused together = carpace
Abdomen:
7 segments
7th segment = telson

6. External Features 2 pairs of antennae/feelers Chelipeds-modified claws
Mandibles
Maxillae
Maxillipeds
Chelipeds-modified claws
Larger claw crushes prey
Smaller claw holds and tears food
Walking legs
Swimmerets
Uropod- tail flips

7. Crayfish A freshwater crustacean
A decapod: 10 feet composed of 5 pairs of legs. Shrimps and Crabs are also decapods.

8. Crayfish parts

9. Feeding Crayfish are bottom dwellers
Eat things such as worms, slugs, bugs and vegetation
Minimal effort into hunting but will eat small fish that inhabit the area they live in

10. Digestion Food  esophagus  stomach intestine  anus
teeth made of chitin and calcium carbonate grind the food into a fine paste
Paste mixed with enzymes secreted by a digestive gland
Move to intestine for digestion and absorption.
Indigestible material is excreted through the anus

11. Crustacean Excretion H20 constantly enters tissues by osmosis
Have green glands
Eliminates excess water
Through pore at base of antennae

12. Respiration
Gills:
Extend from base of walking leg into chamber under carapace
Legs circulate H2O across gills
Permits gas diffusion

13. OPEN Circulatory System

14. Nervous System/Response
Brain that consist of ganglia
Receive nerve impulses from eyes & antennules
Ventral nerve cord
Sense vibrations and chemical in water
Small sensory hairs on exoskeleton

15. Reproduction
Male deposits sack filled with sperm on the underside of the females belly
Female release eggs to sperm
Embyro free swimming naupilus  molts  adult
3 pairs of appendages
single eye