phylum porifera(sponges) cnidaria(hydra & jellyfish) platyhelminthes (flatworms)

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Major Aquatic Invertebrate Taxa. Phylum Porifera(sponges) Cnidaria(hydra & jellyfish) Platyhelminthes (flatworms) Gastrotricha(gastrotrichs) Rotifera(rotifers) Nematoda(nematodes) Mollusca(snails/bivalves) Annelida(oligochaetes/leeches) Bryozoa(moss animals) - PowerPoint PPT Presentation

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  • PhylumPorifera(sponges)Cnidaria(hydra & jellyfish)Platyhelminthes (flatworms)Gastrotricha(gastrotrichs)Rotifera(rotifers)Nematoda(nematodes)Mollusca(snails/bivalves)Annelida(oligochaetes/leeches)Bryozoa(moss animals)Tardigrada(water bears)Arthropoda(arthropods)Major Aquatic Invertebrate Taxa

  • Review of major invert classifications--Radially symmetrical animalsPhylum: Cnidaria

    --Bilaterally symmetrical animals

    Acoelomates animals that lack a body cavity: Phylum: Platyhelminthes

    Pseudocoelomates animals that have a body cavity but no peritoneum.Phlya: Gastrotricha, Nematoda, Rotifer

    Coelomates animals with internal body cavity lined with peritoneum.

    Protostomes:Phyla: Mollusca, Annelida, Tardigrada, Arthropoda Deuterostomes:Phyla: Echinodermata, Chordata

  • PhylumPorifera(sponges)Cnidaria(hydra & jellyfish)Platyhelminthes (flatworms)Gastrotricha(gastrotrichs)Rotifera(rotifers)Nematoda(nematodes)Mollusca(snails/bivalves)Annelida(oligochaetes/leeches)Bryozoa(moss animals)Tardigrada(water bears)Arthropoda(arthropods)Major Aquatic Invertebrate Taxa

  • Phylum: PoriferaAbout 5,000 species worldwideAbout 25 species are freshwater

  • Collection and Identification of sponges

  • Pinacocytes: skin cells, thin, leathery and tightly packed.

    Choanocytes: striking resemblance to choanoflagellates(a single-celled protist). Their function is to create active pumping of water and major site of nutrient uptake.

    Archaeocytes: These cells are totipotent. They can change into all of the other types of cells. Ingest and digest food caught by choanocyte collars.

    Schlerocytes: Create and excrete spicules.General physiology

  • Reproduction--All sponges can reproduce sexually

    --Generally monoecious and produce eggs and sperm at different times.

    --Produce flagellated parenchymella larva that exit via exhalent current.

    --Larval motility is the principal dispersal mechanism

    --Sponges have great powers of regeneration

  • Feeding--Sponges feed on fine particulate material in the inflowing water.

    --Food particles generally range from 5- to 50 m and are phagocytized by archeocytes.

    --After digestion is complete, the archeocytes and associated wastes are expelled into the water.

  • Phylum: CnidariaClass Hydrozoa (only freshwater rep)over 3,000 speciesonly 14 freshwater speciesClass Cubozoa (sea wasps)Class Scyphozoa (jellyfishes)Class Anthozoa (sea anemones and corals)

  • polypmedusaDimorphism in Cnidaria

  • Reproduction--Cnidarians reproduce both asexually and sexually. Medusa are produced by budding of polyps but not vice versa.

    --Generally dioecious and reproduce sexually during warmer periods.

    --Embryos develop into ciliated free-swimming larva called planula.

  • Crespedacusta bowersi the only freshwater jellyfish

  • Feeding--Cnidarians are carnivorous but have limited powers of movement.

    --Essential to the feeding process are thin, flexible tentacles.

    --Nematocysts are specialized cells located on tentacles that aid in capture of prey.

    --Amino acids released by prey can trigger the tentacles to bend toward the mouth by ciliary action.

    --Common foods of Hydra include invertebrates and sometimes small fish.

  • Nematocycts Food, protection, anchoring

  • PhylumPorifera(sponges)Cnidaria(hydra & jellyfish)Platyhelminthes (flatworms)Gastrotricha(gastrotrichs)Rotifera(rotifers)Nematoda(nematodes)Mollusca(snails/bivalves)Annelida(oligochaetes/leeches)Bryozoa(moss animals)Tardigrada(water bears)Arthropoda(arthropods)Major Aquatic Invertebrate Taxa

  • Review of major invert classifications--Radially symmetrical animalsPhylum: Cnidaria

    --Bilaterally symmetrical animals

    Acoelomates animals that lack a body cavity: Phylum: Platyhelminthes

    Pseudocoelomates animals that have a body cavity but no peritoneum.Phlya: Gastrotricha, Nematoda, Rotifer

    Coelomates animals with internal body cavity lined with peritoneum.

    Protostomes:Phyla: Mollusca, Annelida, Tardigrada, Arthropoda Deuterostomes:Phyla: Echinodermata, Chordata

  • Platyhelminthes (flatworms):

    Free living- Class Turbellaria (planarians)mostly predaceousfree livingepidermal rhabdites

    Parasitic Class Trematoda (internal flukes)exclusively parasiticcomplicated life-cyclesClass Cestoda (tapeworms)exclusively parasitic

  • Platyhelminthes (flatworms):Trematodes --- black spot disease; yellow grub

  • PlanarianDugesiaPhylum: PlatyhelminthesAbout 200 species in N. America

  • Turbellarians: General morphologyepidermismesenchymegutrhabditesneoblasts

  • General physiology--Triploblastic (3 layers). 0.5 to 5 cm long.

    -- Respire/excrete by diffusion.

    -- No body cavity other than gut. No anus.

    --Rhabdoids: Cells that produce mucus and poison for prey immobilization/predator deterrence.

    --Neoblasts: Small, ameboid like cells that initiate regeneration of lost parts.

  • Identification of planariansNutritive cellsSimple intestine3-lobed intestineMany-lobed intestineAcoela Neorhabdocoela Tricladids Polycladids

  • Reproduction--Most turbellarians are monoecious.

    --Penal stylets (Penis) that can be used for both reproduction and defense.

    --Embryos develop into a free-swimming, ciliated stage called Mullers larva. Short-lived, nonfeeding stage.

    --Can produce asexually by fission, fragmentation or both.

  • Life history and ecologySome species are univoltine:

    produce one generation a yearMost turbellarians are multivoltine:

    produce several generations a year--Widely distributed in N. America

    --Occur in both lakes and streamsStream-dwelling species more differentiated than lake species

    --Species diversity increases in temperate areas 20 to 60 species per lake

  • Feeding--Effective predators on other invertebrates including rotifers, nematodes, cnidarians, bryozoans, small crustaceans, annelids and other turbellarians.

    --Turbellarians use slime to entangle prey. They use a muscular protrusible pharynx to help ingest prey.

  • PhylumPorifera(sponges)Cnidaria(hydra & jellyfish)Platyhelminthes (flatworms)Gastrotricha(gastrotrichs)Rotifera(rotifers)Nematoda(nematodes)Mollusca(snails/bivalves)Annelida(oligochaetes/leeches)Bryozoa(moss animals)Tardigrada(water bears)Arthropoda(arthropods)Major Aquatic Invertebrate Taxa

  • Review of major invert classifications--Radially symmetrical animalsPhylum: Cnidaria

    --Bilaterally symmetrical animals

    Acoelomates animals that lack a body cavity: Phylum: Platyhelminthes

    Pseudocoelomates animals that have a body cavity but no peritoneum.Phlya: Gastrotricha, Nematoda, Rotifer

    Coelomates animals with internal body cavity lined with peritoneum.

    Protostomes:Phyla: Mollusca, Annelida, Tardigrada, Arthropoda Deuterostomes:Phyla: Echinodermata, Chordata

  • Phylum: GastrotrichaAbout 450 speciesFewer than 100 freshwater species

  • Gastrotrichs--Nearly ubiquitous in the benthos of freshwater habitats.10,000 to 100,000 per m2.

    --Colorless animals 50 to 800 um long.

  • General physiology--Sensory organs include ventrally located cilia

    --Most are photosensitive

    --Most species exhibit tactile chemical sense.

    --Excretory system consists of a midbody pair of protonephridia that empty through pores on the body surface.

    --No circulatory or respiratory system per se.

  • Reproduction--Believed to produce 3 types of eggs:

    2 types are parthenogenic 1) tachyblastic eggs develop immediately and hatch quickly (within 1-2 days)2) opsiblastic eggs thick shelled resting eggs that are very resistent to freezing and drying

    1 type of sexual reproduction?

    --Newly hatched Gastrotrichs already have parthenogenetic eggs and reach maturity in several days.

    --No larval stage in gastrotrichs.

  • OPSITACHY(2N)(N)Gastrotrich reproductionjuvenileparthenogenetichermaphroditic

  • Feeding ecology--Gastrotrichs typically feed on bacteria, algae, protozoans, detritus and inorganic particles.

    --Bacteria are probably most important.

    --Predators include amoeba, cnidarians and midge larvae.

    --We know very little about what controls gastrotrich populations in the natural environment.

  • Phylum:RotiferaThe wheel animals

  • Rotifers--About 2000 species (mostly freshwater)

    --Possess 2 distinctive features:1) ciliated corona near head region2) a muscular pharynx, the mastax

    --Small, (100-1000 um) herbivores and predators.

    --Can be very abundant (up to 1000/L) and found in nearly all habitats from open water to soils and attached to plants.

    --Exhibit cyclomorphosis

    --Two major classes:1) Bdelloidea2) Monogononta

  • Rotifer diversity

  • General Rotifer morphology

  • Rotifer reproduction--Rotifers are dioecious and males are always smaller than females.

    --Parthenogenesis predominates, but males do appear sporadically.

    -- Mostly oviparous; producing 3-50 eggs.

    --Monogononta have only 1 gonad; Bdelloidea has paired gonads but no males are known.

  • --2 types of females: Amictic and dimictic. Morphologically indistinguishable, but functionally distinct.Rotifer life-cycle

  • Functional role--Because of their sheer abundance and quick turnover time, they can exert significant grazing pressure on phytoplankton.

    --Can represent up to 50% of zooplankton production in lakes/ponds.

    --Generally have lower filtering rates as com

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