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Invertebrates I: Porifera, Cnidaria, Ctenophora, Platyhelminthes, Annelida, Sipuncula, Echiura

Invertebrates I: Porifera, Cnidaria, Ctenophora, Platyhelminthes, Annelida, Sipuncula, Echiura. Tree of Life. Invertebrates - Background Kingdom Animalia 97% of all animal species are invertebrates Animals without a backbone

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Invertebrates I: Porifera, Cnidaria, Ctenophora, Platyhelminthes, Annelida, Sipuncula, Echiura

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  1. Invertebrates I:Porifera, Cnidaria, Ctenophora, Platyhelminthes, Annelida, Sipuncula, Echiura

  2. Tree of Life

  3. Invertebrates - Background • Kingdom Animalia • 97% of all animal species are invertebrates • Animals without a backbone • All major groups have marine representatives (some are exclusively marine) • (3-15 million species)

  4. Phylum Porifera (Sponges) • Simplest multicellular animals • Most are marine (~9000 species) • Sessile (attached to substrate) • Diversity of shapes, sizes, colors, habitats • Found from low tide line to 3.5 miles deep

  5. Cellular organization-complex aggregation of specialized cells • No true tissues/organs, cells largely independent from each other • No organs, movable parts, appendages • Thus, cells are plastic, can change from one type to another Fig. 7.2

  6. Shapes: Tiny cups, broad branches, tall vases, encrusting round masses

  7. Phylum Porifera (Sponges)-Gr. “pore-bearers” Complex sponge many chambers, oscula Simple sponge 1 chamber, 1 osculum • Body Plan (Structure)- Asymmetrical • Ostia – water enters-pumped through these pores • Choanocytes – Collar cells; line chambers • Beat flagella to pump water through sponge • traps food particles • Osculum – water exits (driven by collar cells acting in synch) • Spongin – Elastic protein (spongy texture) • Spicules – Calcareous or siliceous structures, structural support, discourage predators • Amebocytes (wandering cells)– Secrete spongin and spicules, transport and store food particles, transform into other types of cells, repair

  8. Water-OUT through osculum Water/food IN through ostia • Phylum Porifera (Sponges) Feeding (Digestion is intracellular) Suspension feeders Filter feeders (active suspension feeders) Reproduction Asexual budding, break off tips of branches “branches” regenerate, identical to parent Sexual

  9. Most are hermaphrodites • both male and female structures produce both types of gametes (eggs and sperm) • Broadcast spawning of sperm (clouds) • swept into sponge • fertilize eggs • eggs develop into larvae • swept out via water currents Fig. 7.3

  10. II. Phylum Porifera • 3 classes – defined by internal skeleton • Class Calcarea • CaCO3 spicules • Shallow tropical waters (Leucosolenia, Scypha, Leucandra, Leucilla) • (drawing of Scypha slide)

  11. II. Phylum: Porifera • Class Hexactinellida • Glass sponges, silica spicules • Deep waters • (Euplectella specimen-Venus’s flower basket sponge, spicules slide) • Gr. Plecta = lace, this genus is known for lace-like skeleton fused glass spicules

  12. II. Phylum: Porifera • Class Demospongiae • Silica, spongin, or both, or lack skeleton • Bath sponge, rounded, spongin fibers • Encrusting forms, bright colors on rocks and corals • Boring types, through CaCO3 • (Spongia specimen, note siliceous spiculation, internal budding)

  13. Phylum Cnidaria • Big steps from simple sponges to evolution of tissues • > 10,000 species • All are aquatic, mostly marine • Sea anemones • Corals • Jellies

  14. III. Phylum Cnidaria Radial symmetry- similar parts of body are arranged and repeated around central axis. Look the same from all sides and have neither head or tail, front or back Oral surface (mouth) Aboral surface (opposite) Fig. 7.5

  15. III. Phylum Cnidaria 2 basic forms • Polyp: anemone, tube with a mouth surrounded by tentacles, specialized in sedentary (sessile) life attached to substrate • Medusa: jellyfish, bell-shaped free-floating, swim by pulsating contractions

  16. III. Phylum Cnidaria-feeding No true organs Tube/sac with single opening (mouth) Mouth opens to gut Tentacles capture food • CNIDOCYSTS (stinging cells, NOTE NAME) • Defense • Prey capture • Contain NEMATOCYSTS =thread bag (stinging capsule) • Simple nervous system Trap food using mucus secreted at mouth and tentacles Some with symbiotic zooxanthellae, provides host with nutrients, O2, use up CO2

  17. Cnidocyte with nematocyst Trigger hair fluid coiled thread Undischarged < 0.1 mm Discharged www.calacademy.org/research/izg/nematocyst.htm

  18. III. Phylum Cnidaria • Reproduction-asexual and sexual, details to follow • Asexual • Budding, binary fission (split down lateral axis), regenerate • Sexual

  19. III. Phylum Cnidaria 4 Classes of cnidarians Class Hydrozoa (includes hydras, hydroids, hydromedusae, chondrophorans, siphonophores, hydrocorallines) Feathery, bushy colonies of tiny polyps attach to pilings, shells, surfaces Alternate between polyp and medusa form

  20. III. Phylum Cnidaria Class Hydrozoa • Polyp forms • colonial • Specialized polyps (zooids) • Gastrozooid - Feeding • Gonozooid – Reproduction • Dactylozooid – Defense (tentacles), studded with nematocysts • (examples: Hydra with budding (Hydra littoralis), Hydra nematocyst slides • Medusa forms • Siphonophores – Colonial (e.g.- Portugese man of war) – polyps and medusa forms simultaneously • Medusae serve as floats-propel colony through water • Polyp morph represented by gastrazoids, gonozooids, and dactylozooid (Obelia colony slide (label gastrozoids and gonozooids), Obelia medusa slide)

  21. III. Phylum Cnidaria, Class Hydrozoa gastrozooid gonozooid

  22. Fig. 7.7

  23. III. Phylum Cnidaria Class Scyphozoa-jellyfishes • All marine species, few hundred • Medusae large (dominant stage) • E.g. – Cyanea capillata (Lion’s Mane) • Bell > 2 m • Tentacles 60+ m • Swim by contracting bell rhythmically, pulsing contraction, at mercy of currents • Stings *, sometimes fatal Desmonema glaciale Aurelia aurita

  24. Cyanea capillata

  25. III. Phylum Cnidaria Class Anthozoa (most are) • Polyp (more complex than hydrozoan, scyphozoan • Sexes usually separate • Oviparous (egg-bearer) and viviparous (young bearing) • Passive suspension feeders • Solitary forms • Sea anemones • Colonial forms • Corals • Stony corals – branching and massive • - Some build reefs • Soft corals • Gorgonians • Sea pens • Sea pansies • (Drawings: Brain coral and Gorgonian specimen) Anthopleura xanthogrammica

  26. Branching Corals Doming Corals

  27. Sea Pen Soft Corals Sea Pansy

  28. Gorgonians (Sea Whips)

  29. Gorgonians (Sea Fans)

  30. III. Phylum Cnidaria Class Cubozoa, “scyphozoa cubed” • Sea wasps, Box jellyfish • square bell-cuboidal swimming bell • 4 tentacles or bunches • Highly toxic

  31. IV. Phylum Ctenophora (comb-bearing) Exclusively Marine (100 species) Aka comb jellies Resemble Cnidarians Most primitive Biradial symmetry (radial + bilateral symmetry) • 8 rows of ciliary combs (ctenes) • Equally spaced on body surface • Each row is a ridge, paddle of fused cilia • Beat aboral to oral, propels mouth forward • Organ system: Digestive system-mouth to pharynx to stomach • Predatory and Carnivorous • Lack nematocysts • Capture prey with sticky colloblasts • May occur in swarms • Heavy predators • (consume lots of fish larvae)

  32. Pleurobrachia Beroe

  33. Flatworms - Dorsoventrally flattened Flatness enables O2/CO2 exchange, hiding Bilateral symmetry Simplest organisms with organs and organ systems Central nervous system, organs Digestive tract has 1 opening (like Cnidarians and ctenophores) No circulatory, respiratory, skeletal systems Hermaphroditic V. Phylum Platyhelminthes

  34. V. Phylum Platyhelminthes Class Trematoda (Flukes) • Largest group of flatworms (6000 species) • Parasitic – Feed on tissues, blood, gut contents • Complex life cycles • Adults in vertebrate • Larvae in invertebrates • Vertebrate eats intermediate host (fluke larvae) • Body covered with cuticle resistant to digestion • Clonorchis slide (label suckers), common liver parasite

  35. V. Phylum Platyhelminthes Class Cestoda (Tapeworms) • Parasitic • Live in vertebrate intestines – (uncooked meat) • Head attaches w/4 suckers or hooks • Gutless – absorb nutrients through body wall • Body covered with cuticle resistant to digestion • 50 feet!! (sperm whales) • Dipylidium slide (label solex-head w/4 suckers, and proglottid-sections onneck)-common dog tapeworm • Proglottids stem from neck at rate of several per day (fast growth)

  36. V. Phylum Platyhelminthes C. Class Turbellaria • Mostly free-living carnivorous species • commensal animals-live in close relation to other animals, or on their surface, (oysters, crabs, etc.) • Most commonly seen marine flatworm (Why?) • Planaria slide (label ocelli=eyespots) • Planarians are the freshwater species

  37. VI. Phylum Annelida Segmented worms (1mm-3m) – flex/move more easily • Internally and externally, internal structures in tandem • Protective elastic cuticle • Bilateral symmetry • Digestive system of many has 2 openings, mouth and anus (some have no gut) Body composed of repeated segments • Gut runs through all segments in body cavity (coelom-space around gut) • Coelom filled with fluid – hydrostatic skeleton • Coelom divided with septa-correspond to segments

  38. Leech Sabella pavonina Nereis sp. Lumbicus terrestris

  39. VI. Phylum Annelida Class Polychaeta – tube worms, feather dusters • Body segments have pairs of parapodia • Parapodia for locomotion, feeding, gas exchange, protection • tipped with setae (bristles), often 4 pairs • Respiration: some with gills, exchange through body

  40. VI. Phylum Annelida Class Polychaeta • Larva = Trochophore • Band of cilia around body • Diverse lifestyles (mostly benthic, some pelagic) • Free-living predators • Burrowing • Tube building • (parapodia slide, feather duster)

  41. Fig. 7.14

  42. VI. Phylum Annelida Class Oligochaeta - earthworms • Few marine species • Benthic – mud and sand (deposit feeders) • No parapodia • Locomotion – expansion and contraction • (oligochaete slide) © 2004 Amanda Demopoulos ©2004 Amanda Demopoulos

  43. VI. Phylum Annelida • Class Hirudinea (Leeches) • Freshwater mostly • No parapodia • One anterior/one posterior sucker to attach • Hirudin – anticoagulating chemical so blood does not clot • (leech specimen)

  44. VII: Phylum Echiura • Sand/mud burrows, rock crevices • 140 species so far, shallow mostly • Mm to 8 cm • Proboscis-used for feeding, contains brain, can’t be retracted • May extend > 25 times size of animal (200 cm for 8 cm animal) • Cilia move food to gut • Most are deposit feeders (few suspension feeders) • Trochophore larvae • Bonellia viridis (males contained w/in females-up to 20) • Sex of embryos not determined at fertilization • Only at contact with female’s proboscis (turns male)

  45. VIII: Phylum Sipuncula • All marine, 350 species • Vermiform – worm shaped, no segments • Found in burrows, sand, mud, shells, tubes • Introvert-unlike proboscis, can be retracted into body • Lack circulatory system w/heart and blood vessels • Pelagospera larva-trochophore larva develop into this, can disperse over long distances • http://www.flickr.com/photos/80125969@N00/256020109/

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