CHAPTER 7 MARINE INVERTEBRATES

OBJECTIVES DESCRIBE THE FEATURES OF INVERTEBRATE MARINE ORGANISMS SPECIFICALLY INCLUDE: CNIDARIANS, WORMS, MOLLUSKS, ARTHROPODS, AND ECHINODERMS

ANIMAL SYMMETRY ANIMALS ARE OFTEN GROUPED AND CLASSIFIED ACCORDING TO THE GEOMETRIC SYMMETRY OF THEIR BODIES. BILATERAL SYMMETRY: BODY CAN BE DIVIDED IN HALF BY A SINGLE PLANE. THE HALVES ON EACH SIDE OF THE PLANE ARE A NEAR MIRROR IMAGE. RADIAL SYMMETRY: BODY PARTS ARE ARRANGED AROUND A CENTRAL AXIS. BODY CAN BE SPLIT LIKE A PIZZA INTO IDENTICAL PARTS.

CLASSIFICATION OF LIVING THINGS KINGDOM – ANIMALIA, PLANTAE, FUNGI, PROTISTA, BACTERIA PHYLUM CLASS ORDER FAMILY GENUS ▪ SPECIES Human Classification: Kingdom: Animalia Phylum: Chordates Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: sapiens

INVERTEBRATES  SOFT-BODIED ORGANISMS WITHOUT A BACKBONE  MAJOR PHYLA IN ORDER OF INCREASING COMPLEXITY 1.PORIFERA 2.CNIDARIA 3.WORMS 4.MOLLUSCA 5.ARTHROPODA 6.ECHINODERMATA

PHYLUM: PORIFERA “HOLE BEARING”  EXAMPLES: SPONGES  THE MOST PRIMITIVE ANIMALS  NO SYMMETRY  SESSILE (DOESN’T MOVE) AND BENTHIC (LIVES ON THE BOTTOM)  ALMOST ALL ARE MARINE  DEPEND ON CURRENTS FOR FEEDING AND SEXUAL REPRODUCTION.  NO DIGESTIVE, CIRCULATORY, RESPIRATORY, OR NERVOUS SYSTEM

PHYLUM: CNIDARIA “NETTLE”  EXAMPLES: CORALS, ANEMONES, JELLYFISH, HYDRA  CONTAIN STINGING CELLS: NEMATOCYSTS  USED TO STUN PREY  RADIALLY SYMMETRICAL (CAN BE DIVIDED LIKE A PIZZA AND ARE EQUAL)  SIZE RANGE: MICROSCOPIC TO 20M (60 FEET!)  CARNIVOROUS: STUN PREY AND USE TENTACLES TO MOVE IT TO MOUTH

 TWO FORMS: POLYP AND MEDUSA  POLYP: SESSILE, MOUTH AND TENTACLES FACE UP  MEDUSA: PLANKTON, MOUTH AND TENTACLES FACE DOWN  SIMPLE DIGESTIVE AND NERVOUS SYSTEMS

WORMS BILATERALLY SYMMETRICAL: TWO EQUAL HALVES  POSSESS DIGESTIVE AND NERVOUS SYSTEMS (SMALL BRAIN)  WELL FORMED TISSUES AND ORGANS THREE PHYLA: PLATYHELMINTHES NEMATODA ANNELIDA

PHYLUM: PLATYHELMINTHES – FLAT WORMS EX – FLUKES, TAPEWORMS, MARINE FLATWORMS PREDATORS AND SCAVENGERS; SOME ARE PARASITES SMALLER THAN 3CM REPRODUCE ASEXUALLY AND SEXUALLY; INDIVIDUALS HAVE BOTH TESTES AND OVARIES.

 PHYLUM: NEMATODA – ROUND WORMS  EX. HOOKWORMS  COMPLETE DIGESTIVE SYSTEM (MOUTH AND ANUS)  REPRODUCE SEXUALLY – DISTINCT MALE AND FEMALE FORMS  PRESENT IN ALMOST ALL TYPES OF ENVIRONMENTS  MOST ARE MICROSCOPIC PARASITES  PHYLUM: ANNELIDA – RING WORMS  EX. EARTHWORMS, LEECHES, MARINE TUBEWORMS AND POLYCHAETES  BODIES DIVIDED INTO SEGMENTS  EACH SEGMENT CAN HAVE ITS OWN CIRCULATORY, RESPIRATORY, EXCRETORY, NERVOUS, MUSCULAR AND REPRODUCTIVE SYSTEM

Platyhelminthes Annelida

PHYLUM: MOLLUSCA = SOFT BODIED EX. CLAMS, CHITONS, SQUID, OCTOPUS, SNAILS HAVE AN EXTERNAL OR INTERNAL SHELL BILATERALLY SYMMETRICAL WELL-DEVELOPED NERVOUS AND DIGESTIVE SYSTEMS

PHYLUM: MOLLUSCA: THREE MAIN CLASSES: GASTROPODA: “STOMACH FOOT” SNAILS, CONCH, ABALONE 1 EXTERNAL SHELL BIVALVIA: “TWO DOOR” CLAMS, OYSTERS, SCALLOPS 2 EXTERNAL SHELLS CEPHALOPODA: “HEAD FOOT” SQUID, OCTOPUS INTERNAL SHELL

PHYLUM: ARTHROPODA “JOINT FOOT”  EXAMPLES:  LOBSTER, CRABS, KRILL, SHRIMP, CRAYFISH, AMPHIPODS, BARNACLES, COPEPODS  LARGEST PHYLA  STRONG EXOSKELETON  STRIATED MUSCLE (QUICK MOVEMENT)  ARTICULATED APPENDAGES: CAN BEND  CLASSES: CRUSTACEA (SEA), INSECTA (LAND)

CRUSTACEANS

PHYLUM: ECHINODERMATA HEDGEHOG SKIN EX. SEA STARS, SAND DOLLARS, URCHINS, SEA CUCUMBER ALL ARE MARINE RADIALLY SYMMETRICAL: BASED ON FIVE LARVAE ARE BILATERALLY SYMMETRIC LACK EYES, HEART, AND BRAINS CALCIFIED ENDOSKELETON COVERED BY SKIN WATER VASCULAR SYSTEM REPRODUCE SEXUALLY SLOW MOVING BENTHIC REGENERATION OF LIMBS, ORGANS, OR SPINES

Oral surfaceAboral Surface Copy this for the study guide! Eyespot Ambulacral groove Tube feet Madroporite Mouth Arm Central disk