BIOL 112 – Chapter 33: The Invertebrates PDF

BIOL 112 – Chapter 33 The Invertebrates  General Points About Invertebrates Contains all the phyla except part of phylum Chordata Most species are marine or aquatic Defining characteristic – Lack of a backbone Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostom...

BIOL 112 – Chapter 33 The Invertebrates  General Points About Invertebrates Contains all the phyla except part of phylum Chordata Most species are marine or aquatic Defining characteristic – Lack of a backbone Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia  Phylum Porifera – Sponges ~ 9,000 species Sessile animals with no true tissues (no nerves or muscles) Primarily marine Suspension feeders Hermaphroditic Can reproduce asexually by fragmentation Grantia (class Calcarea) Class Hexactinellida Yellow Barrel Sponge (class Demospongae) Encrusting Sponge Porifera Eumetazoa Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia  Phylum Cnidaria ~ 10,000 species Simple body plan with two forms Single central cavity & single opening Predatory – Capture using tentacles with cnidocytes  Muscles & Nerves Very simple muscles made of bundles of contractile microfilaments Movements controlled by a nerve net (no brain) Sensory receptors feed into nerve net allowing stimulus/response Colonial Hydroid on Coralline Algae Velella velella Various Hydrozoan Medusas – California Coast Pelagia colorata Haliclystus – Stalked Jellyfish Chrysaora fuscescens – Sea Nettle Sea Wasp – Chironex fleckeri Sea Wasp Stings Anthopleura elegantissima – Aggregating Anemone Tealia crassicornis Balanophylla elegans – Orange Cup Coral Cup coral with tentacles extended Porifera Cnidaria Bilateria Lophotrochozoa Ecdysozoa Deuterostomia  Lophotrochozoa Molecular-defined clade Lophophore – a crown of ciliated tentacles that functions in feeding Trochophore larvae Some members share neither of the above traits  Acoelomates – Phylum Platyhelminthes ~ 20,000 species Free-living & parasitic Body dorsoventrally flattened More complex (have mesoderm) with true muscles, gastrovascular cavity with one opening 4 Classes – Turbellaria, Monogenea, Trematoda & Cestoidea  Class Turbellaria Mostly free-living and marine (Dugesia is aquatic) No respiratory or circulatory system Excrete nitrogenous waste through skin Planarians (e.g. Dugesia) – Move by cilia on slime trail – Head with eyespots & lateral flaps for smell – Hermaphroditic, sexual or asexual Dugesia A Marine Turbellerid Worm  Class Trematoda – Flukes Live primarily as internal parasites Specialized for reproduction Complex life cycles with sexual and asexual stages and sometimes intermediate hosts. Schistosoma mansoni Lung Fluke  Class Cestoidea – Tapeworms Parasitic, hermaphroditic No digestive tract Scolex with hooks attaches to host Mature proglottids release eggs – Expelled in feces and ingested by alternate host – Alternate hosts can be pigs, cows or even fleas – Mature tapeworms in humans can reach 20 m! Taenia Scolex Native of New Guinea eating a tapeworm from a tree kangaroo.  Phylum Rotifera ~ 1,800 species Mostly aquatic, size of protists, but multicellular Complete digestive tract Fluid filled pseudocoelom acts as circulatory system Reproduction by parthenogenesis – Generally all females – Other times both sexes, but males degenerate and only make sperm & die  Lophophorates: Ectoprocts and Brachiopods Lophophorates have a lophophore, a crown of ciliated tentacles around their mouth Lophophorates have a true coelom Lophophorates include two phyla: Ectoprocta and Brachiopoda  Bryozoans Ectoprocts (also called bryozoans) are sessile colonial animals that superficially resemble plants A hard exoskeleton encases the colony, and some species are reef builders Occur in both fresh and saltwater  Bryozoans Kelp encrusting marine bryozoan Freshwater bryozoan colony Lophophores, marine bryozoan  Brachiopods Brachiopods superficially resemble clams and other hinge-shelled molluscs, but the two halves of the shell are dorsal and ventral rather than lateral as in clams Brachiopods are marine and most attach to the seafloor by a stalk  Brachiopods Lophophore in a marine brachiopod  Phylum Mollusca 150,000+ species, mostly marine, some aquatic or terrestrial Most have a hard calcium carbonate shell Includes shellfish, snails, slugs, squids and octopuses, all having a common body plan Larval planktonic stage called trochophore in marine mollusks 8 Classes  Class Polyplecophora – Chitons Entirely marine Shell composed of eight plates, mantle sometimes covering shell. Foot used for locomotion Head reduced, radula present Grazers Tonicella lineata – Lined Chiton Katharina tunicata – Leather Chiton Cryptochiton – Gumboot Chiton  Class Gastropoda 40,000+ species Asymmetrical body, torsion. Coiled shell in most Foot for locomotion Radula Herbivores (grazers) or predators Littorina sp - Periwinkle Cypraea – Cowries Conus pennaceus – Cone Shell Collisella – Limpets Trinchesia cocochroma – Brown Aeolid Hermissenda crassicornis – Glowing Nudibranch Haplotrema sportella – Land Snail Banana Slug  Class Bivalvia Flattened with shell in two halves Head reduced, no radula Paired gills, mantle modified into siphons Suspension feeders Attach to rocks or pilings by byssal threads or burrow in sand or mud using foot Anodonta anatina – Duck Mussel Panope generosa - Geoduck Razor Clam Pholas dactylus Tridacna Squamosa – Giant Clam Hinnites giganteus – Rock Scallop  Class Cephalopoda No or very reduced internal shell (except in nautiluses) Mantel covers visceral mass Mouth at center of several long tentacles Beak used to inject venom Use water jets for locomotion Ink gland used to deter predators Well-developed brain & nervous system, advanced sensory organs, closed circulatory system Octopus dofleini – Giant Pacific Octopus Blue Ring Octopus Loligo opalescens – Opalescent Squid Giant Squid Exhibit Chambered Nautilus  Phylum Annelida – Segmented Worms ~15,000 species Marine, aquatic, moist soil Segmented body, complex digestive system, closed circulatory system Waste removed and expelled by metanephridia Hermaphroditic but cross-fertilizing, sometimes asexual. Recent Classification of Annelida Recent molecular analyses indicate that the annelids can be divided into two major clades – Errantia – Sedentaria  Errantians Most members of clade Errantia are mobile, marine organisms Many errantians have a pair of paddle-like or ridge-like structures called parapodia (“beside feet”) on each body segment Each parapodium has numerous chaetae, bristles made of chitin Parapodia are not unique to this clade  Sedentarians Sedentarians tend to be less mobile than errantians Some species burrow into the substrate, while others live in protective tubes Tube-dwelling sedentarians often have elaborate gills or tentacles used for filter feeding This clade also contains the leeches and the earthworms Earth Worm Nereis virens – Clam Worm Serpula vermicularis – Red Tube Worm Rag worm (Nereis) Head Platynereis Trochophore Medicinal Leeches Haementeria ghilianii  Leech in Eye Leeches in the eye of an unfortunate soul who drank from the wrong pond in India. Porifera Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia  Ecdysozoa Molecular based clade Organisms that molt their exoskeleton. Nematoda & Arthropoda  Phylum Nematoda - Roundworms ~ 90,000 species, maybe ~ 900,000 exist Parasitic & free-living Unsegmented, tapered at both ends, fluid filled pseudocoelom, longitudinal muscles Male & female, sexual, resistant zygotes Abundant in soil & detritus  Notable Nemotodes Caenorhabditis elegans Trichinella spiralis Numerous other parasites in man and other animals Plant root parasites  Ascaris lumbricoides – Worms Expelled from Human Intestines  4 cm ruler Hookworm  Phylum Arthropoda 1,000,000+ species described, 2/3 of all organisms Dominant by sheer numbers Main Characteristics – Segmented (head, thorax & abdomen) – Hard exoskeleton (requires molting) – Jointed appendages This body plan dates to the Cambrian explosion (535–525 million years ago)  Arthropoda - Characteristics Extensive cephalization and well-developed sense organs Open circulatory system with hemolymph Gills or other specialized surfaces for gas exchange  Cheliceriformes – Class Arachnida Scorpions, ticks, spiders, mites Cephalothorax, 1 pair chelicerae, 1 pair pedipalps, 4 pairs of legs Book lungs (rarely tracheae) Spinnerets produce silk in many spiders Limulus polyphemus – Horseshoe Crab Desert Scorpion Theraphosa blondi – Goliath Birdeating Tarantula Lycosa carolinensis – Carolina Wolf Spider Lactrodectus mactans – Black Widow Spider Brown Recluse Brown Recluse American Dog Tick Ixodes scapularis – the black- legged or deer tick Deer Tick Head  Myriopoda – Classes Diplopoda & Chilopoda Class Diplopoda – Millipedes – Wormlike, many legs (2 pairs per segment) – Eat plant material Class Chilopoda – Centipedes – Pair of antennae on head – Three pair of appendages modified as mouth parts, jawlike mandibles – One pair of walking legs per segment – Predators, poison claws Millipede Centipede  Hexapoda – Class Insecta In all terrestrial environments, some aquatic or marine Many fly and have 1-2 pairs of wings Open circulatory system, complex digestive system, Malpighian tubules for excretion Gas exchange by tracheae, open to air by spiracles  Hexapoda – Class Insecta Incomplete vs. complete metamorphosis Reproduction usually sexual Fertilization generally internal, but sperm packets sometimes attached externally  Class Insecta - Orders Coleoptera – beetles Isoptera – termites Dermaptera – earwigs Lepidoptera – butterflies & moths Diptera – flies & mosquitoes Odonata – dragonflies & damselflies Hemiptera – true bugs Orthoptera – crickets, Hymenoptera – bees, grasshoppers, mantids, ants, wasps roaches Phthiraptera – lice Siphonoptera – fleas Anatis rathvoni – Ladybird Beetle Coleoptera Pityobius murrayi – Click Beetle Coleoptera Dung Beetle Coleoptera Forficula auricularia – Earwig Dermaptera Bittacomorpha occidentalis – Phantom Crane Fly Diptera Caliprobola pulchra – Golden Syrphid Fly Diptera Tabanus punctifer – Western Horsefly Diptera Mosquito Diptera Leaf-footed Bug Hemiptera Zelus socius – Leafhopper Assassin Bug Hemiptera Apis mellifera – Honey Bees Hymenoptera Vespula pennsylvanica – Western Yellow Jacket Solenopsis invicta – Red Fire Ant Dasymutilla coccinea – Red- haired Velvet Ant Hymenoptera Reticulitermes hesperus – Western Termite Isoptera Danaus plexippus – Monarch Butterfly Caterpillar Lepidoptera  Danaus plexippus Monarch Butterfly Pupa Lepidoptera Danaus plexippus Monarch Butterfly Lepidoptera Libellula pulchella – Ten-spot Skimmer Dragonfly Odonata Damsel Flies Odonata Stenopelmatus fuscus – Jerusalem Cricket Orthoptera Schistocerca nitens – Gray Bird Grasshopper Periplaneta americana – American Cocroach Orthoptera Stagmomantis carolina – Carolina Mantis Orthoptera  Phthiraptera Head Louse Siphonoptera Dog Flea  Siphonoptera Cat Flea  Subphylum Crustacea ~40,000 species, marine and aquatic Multiple appendages with extreme specialization, 2 pairs of antennae Walking legs on thorax, appendages on abdomen, lost appendages regenerate Gills or simple diffusion for gas exchange Open circulatory system Sexes separate, generally swimming larvae  Classes of Crustacea Class Malacostraca – Order Isopoda – dorsoventrally flattened – Order Amphipoda – Laterally flattened – Order Decapoda – Crabs, shrimp, lobsters, crayfish Class Copepoda – Most abundant primary consumer Class Cirripedia - Barnacles Cirolana harfordi – Isopod Talorchestia megalophthalma Big-eyed Beach-flea Amphipoda Hemigrapsus nudus – Purple Shore Crab Decapoda Panulirus interruptus - California Spiny Lobster Decapoda Callianassa californiensis Ghost Shrimp Decapoda Euphausia pacifica – Krill, Euphasiid Shrimp Aetideopsis armata Copepoda Balanus sp. – Acorn Barnacles Cirripedia Pollicipes sp. – Gooseneck Barnacle Cirripedia Deuterostomes  Phylum Echinodermata ~7,000 species, all marine Early developmental similarities to chordates Radially symmetrical as adults, planktonic larvae bilaterially symmetrical Water vascular system, hydraulic canals & tube feet used in gas exchange, locomotion & feeding Separate sexes, external fertilization Pisaster ochraceus – Ochre Seastar Asteroidea Henricia leviuscula – Blood Starfish Asteroidea Patiria miniata – Bat Star Asteroidea Amphiodia occidentalis – Brittle Star Ophiuroidea Gorgonocephalus eucnemis Basket Star Ophiuroidea Strongylocentrotus purpuratus – Purple Urchin Echinoidea Dendraster excentricus – Eccentric Sand Dollar Echinoidea Crinoidea  Squat Lobster: Allogalathea elegans Squat Lobster (actually a crab) is perched in the center of a crinoid's arms Cucumaria miniata – Red Sea Cucumber Holothuroidea Concentricycloidea