Chapter 36 Section 1 Arthropoda

Characteristics Lobsters, crabs, crayfish, spiders, & insects Arthropods- members of the Phylum Arthropoda Segmented animals with appendages- such as legs & antennae Arthropod means “jointed foot

Characteristics Exoskeleton- protection & support 3 layers of exoskeleton Outer- waxy/protein- prevents water loss and drying out Middle- protection layer made of protein & chitin- tough carbohydrate Inner-flexible/muscles-movement

Characteristics Cephalization- brain/sensory structures located at anterior end Appendages around mouth to aid with feeding Antennae specialized for detecting chemicals

Characteristics Open circulatory system Compound eyes- eyes made of many individual light detectors with lenses

Molting Molting- shedding of the exoskeleton to grow Hormones trigger molting Arthropods usually hide during this stage because they are vulnerable to predators

Evolution & Classification Trilobites- ancient & extinct arthropod Tagma- specialized for feeding, locomotion, & reproduction Two major mouthparts: mandibles- jaw-like chelicerae- pincer-like

REVIEW!!! Name three characteristics of arthropods. Why do arthropods molt?

Section 2 Subphylum Crustacea Chapter 36 Section 2 Subphylum Crustacea

Characteristics Two-pairs of antennae Mandibles Pill bugs, lobster, crayfish Nauplius- free-swimming larva stage

Diversity of Crustaceans Range of sizes, but most are small Copepods- no larger than a comma ( , ) Japanese spider crab- 13 feet

Aquatic Crustaceans Copepods- marine (plankton) Water fleas (Daphnia)- freshwater Barnacles- marine- sessile; attach to many different surfaces Cirri- appendages that sweep food particles into barnacle’s mouth

Terrestrial Crustaceans Isopods- pill or potato bug Lose water quickly through thin exoskeleton Live in moist environments Roll into a ball when threatened as a defense Feed on decaying vegetation

Crayfish Freshwater crustacean Similar to lobster Well-studied because of abundance Decapods- crayfish, lobster, crab, & shrimp (10-feet)

External Structure Body divided into abdomen & cephalothorax- consists of head & thorax- eight segments & lies behind head Carapace- dorsal exoskeleton Abdomen- six segments behind cephalothorax

External Structure Two pairs of antennae- touch & taste Antennules- touch, taste, balance Mandibles- chew food Maxillae- manipulate food & draw water over gills Maxillipeds- manipulate food

External Structure Cheliped- capture food & pincer defense Swimmeret- creating water current & transferring sperm Telson & uropods- paddle-like tail Move in backward movement called “tail flip”

Digestion Esophagus  stomach  teeth-like structures in stomach grind food to fine paste  mixed with enzymes secreted by digestive gland  enters intestine for digestion & absorption  anus

Respiration Feather-like gills for respiration As crayfish walk, circulate water over gills

Circulation Open-circulatory system Circulatory fluid called hemolymph Exchanges carbon dioxide with oxygen in water Gills  dorsal part of crayfish  heart

Excretion Green glands- excess water, along with wastes is eliminated Waste from green glands leaves through a pore at the base of the antennae

Neural Control Ganglia Controls mandibles, maxillae, & maxillipeds Ventral nerve cord runs from the ganglia into the thorax & abdomen

Sensory Organs Sense vibrations & chemicals by sensory hairs over entire body Compound eye sense light

REVIEW!!! Name three appendages of the crayfish and the function of each appendage. How do crayfish digest food? How do crayfish sense their environment?