INVERTEBRATES

YOU MUST KNOW…• THE TRAITS WHICH ARE USED TO

DIVIDE THE ANIMALS INTO GROUPS

• EXAMPLES AND UNIQUE TRAITS FOR EACH PHYLUM DISCUSSED

• THE EVOLUTION OF SYSTEMS FOR GAS EXCHANGE, RESPIRATION, EXCRETION, CIRCULATION, AND NERVOUS CONTROL

INVERTEBRATES• LACK

BACKBONES• 95% OF ALL

KNOW SPECIES ARE INVERTEBRATES

SUBKINGDOM PARAZOA• SPONGES, PHYLA CALCEREA AND SILICEA• SESSILE (ANCHORED), LACK TRUE TISSUES• DIPLOBLASTIC (2 LAYERS OF CELLS)• NO NERVES OR MUSCLES• WATER IS DRAWN THROUGH THE PORES INTO

THE SPONGOCOEL AND FLOWS OUT THROUGH THE OSCULUM THROUGH THE MOVEMENT OF FLAGELLATED CHOANOCYTES

• SPICULES COMPRISE A SKELETAL FRAMEWORK

SUBKINGDOM EUMETAZOA• ANIMALS WITH TRUE TISSUESA. RADIALLY SYMMETRICAL ANIMALS1. PHYLUM CNIDARIA – POLYP (SEA

ANEMONE) AND MEDUSA (JELLYFISH) FORM

GASTROVASCULAR CAVITY (A CENTRAL DIGESTIVE COMPARTMENT), CNIDOCYTES (CELLS THAT FUNCTION IN DEFENSE AND CAPTURING OF PREY)

EX. CNIDARIANS – HYDRAS, JELLYFISH, CORALS

• BILATERALLY SYMMETRICAL ANIMALS

1. ACOELOMATES – NO BODY CAVITYA. PHYLUM PLATYHELMINTHES

(FLATWORMS) – TAPEWORMS, FLUKES

• FLATTENED BODIES WITH CEPHALIZATION, EXCRETION BY FLAME BULBS AND PROTONEPHRIDIA, NO SPECIALIZED ORGANS FOR GAS EXCHANGE OR CIRCULATION, GASTROVASCULAR CAVITY WITH A SINGLE OPENING

2. PSEUDOCOELOMATES

A. PHYLUM NEMATODA (ROUNDWORMS) – PINWORMS, HOOKWORMS

• CYLINDRICAL BODIES WITH A TOUGH CUTICLE, COMPLETE ALIMENTARY CANAL, NO CIRCULATORY SYSTEM

3. COELOMATES

A. PHYLUM MOLLUSCA (SOFT-BODIES ANIMALS) – SLUGS, CLAMS, SNAILS, SQUIDS, AND OCTOPUS

• MUSCULAR FOOT FOR MOVEMENT, A VISCERAL MASS CONTAINING MOST OF THE ORGANS, AND A MANTLE THAT SECRETES A SHELL

• OPEN CIRCULATORY SYSTEM, EXCRETION THROUGH NEPHRIDIA

B. PHYLUM ANNELIDA (SEGMENTED WORMS) – EARTHWORMS, LEECHES

• INTERNAL AND EXTERNAL SEGMENTATION, EXCRETION BY METANEPHRIDIA IN EACH SEGMENT

• CLOSED DIGESTIVE SYSTEM WITH SPECIALIZED REGIONS (CROP, GIZZARD, ESOPHAGUS, AND INTESTINE)

• BRAINLIKE CENTRAL GANGLIA WITH A VENTRAL NERVE CORD, CLOSED CIRCULATORY SYSTEM

C. PHYLUM ARTHROPODA (JOINT-LEGGED ANIMALS) – INSECTS, ARACHNIDS, MILLI- AND CENTIPEDES, CRUSTACEANS

• EXOSKELETON OF CHITIN, MOLTS TO GROW

• JOINTED APPENDAGES, OPEN CIRCULATORY SYSTEM, VARIOUS ORGANS FOR GAS EXCHANGE INCLUDING GILLS, BOOK LUNGS, TRACHEAL SYSTEMS

• VENTRAL NERVE CORDS• UNDERGO METAMORPHOSIS• (INCOMPLETE) – EGG, NYMPH, ADULT

(GRASSHOPPER)• (COMPLETE) – EGG, LARVA, PUPA, ADULT

(BUTTERFLY)

4. DEUTEROSTOMIA• CONTAIN A DIVERSE ARRAY OF

ORGANISMS FROM SEA STARS TO CHORDATES

• HAVE RADIAL CLEAVAGE AND SHARE COMMON DEVELOPMENTAL PROCESSES

A. PHYLUM ECHINODERMATA – SPINY-SKINNED ANIMALS – SEA STARS, SEA URCHINS, SAND DOLLARS, SEA CUCUMBERS

• LARVAE HAVE BILATERAL SYMMETRY, ADULTS RADIATE FROM THE CENTER

• HAVE A THIN SKIN COVERING AN EXOSKELETON

• HAVE A WATER VASCULAR SYSTEM – NETWORK OF INTERNAL CANALS THAT BRANCH INTO TUBE FEET USED FOR MOVING, FEEDING, AND GAS EXCHANGE

B. PHYLUM CHORDATA – INCLUDES 2 INVERTEBRATE SUBPHYLA AS WELL AS ALL VERTEBRATES