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BISC 306 (1)

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Simon Fraser University
Biological Sciences
BISC 306
Michael Hart

BISC306 PORIFERA General: Rigid, perforated bag lined with flagellated collar cells or choanocytes (inside). o Generate currents to maintain circulation o Capture small food particles o Capture sperm Empty space in the middle is called the spongocoel Between inner choanocyte layer and outer pinacocyte (epidermis) layer is the mesohyl. o Gelatinous, acellular o Contains free floating archaeocytes (amoeboid) Digest food, give rise to sperm/eggs, defense, eliminating wastes and specialization for secretion of spicules Spicules are siliceous or calcareous o Discourage predation Spongin is also a supporting material Gemmules are dormant structures from which a sponge emerges o Resistant to dessication, etc o Alternative to tissue regression Pinacocytes form the pinacoderm (outer layer) o Do not secrete a basal lamina o Contractile Ostia (ostium) in, oscula (osculum) out Water comes in through porocytes Asconoids are the simplest body type. A bag. Syconoids are more complex, with pockets of choanocytes Leuconoids lack a large spongocoel. Pockets and pockets of choanocytes increase surface area, and instead of one osculum, they have many oscula. Hermaphroditic, or reproduction by fragmentation Internal fertilization and development Secrete poisons that range from large organic molecules or small ones o Have anticancer, etc, properties Calcarea Demospongiae Hexactinellida Bear CaCO s3icules Spongin or silica spicules (but Supported entirely by never CaCO )3 Also contain interconnected six-rayed chitin. spicules of silica and chitin Include asconoid, syconoid and Nearly all leuconoids Syconoid or leuconoid leuconoid 80% of all sponge species Symmetrical, bilaterally Only asconoids are in this class Outer layer is multi-neuclei-ed No pinacoderm layer CNIDARIA General: Two adult stages o Polyp Mostly stationary Asexually reproduces Tubular body o Medusa Swims Reproduces sexually Not hermaphroditic Basic radial symmetry Two layers of living tissue, separated between them by a mesoglea (gelatinous) o Mesoglea is nonliving but may contain living cells (amoebocytes) o Epidermis and gastrodermis All cnidarians secrete nematocysts o Defensive structures o Secreted within cells called cnidoblasts (or nematoblasts) o Cnidae are the most widespread o Rounded proteinacious capsule with an opening at one end o Hollow tube shoots out explosively, turning inside out o Triggered by chemical and tactile stimulation o Specialization for wrapping small objects, sticking to surfaces, penetrating, secreting toxins o Function in food collection, defense and locomotion (sort of) Food passes through only one hole, the mouth Mostly carnivorous, though some eat phytoplankton Reef building (hermatypic) corals generally have symbiotic algae or something to colour them No central nervous system, but nerves and muscles o Nerve nets o Slow conducting branched nerve system that goes both ways o Less branched fast conducting neurons have more directed transmission Greater diameter, fusion of smaller fibres during development Diploblastic Musculature cannot originate in the mesoderm o Muscle layers are composed of elongated, contractile bases in the mesoglea in the ecto and endodermal cell layers Epitheliomuscular cells Form either longitudinal or circular musculature Mesoglea acts as support system, oxygen store Nematocysts secrete digestive enzymes and then phagocytose and digest intracellularly Planula larvae result from sexual union Polymorphs of polyp colonies o Gastrozooids eat o Gonozooids fuck o Dactylozooids defend Myxozoa (Non-medusozoans) o Extracellular, spore-forming parasites o Possess organelles called polar filaments coiled in polar capsules o No well defined nervous system o Sometimes worm shaped Hydrozoa Anthozoa Cubozoa Scyphozoa Greater polyp No medusa stage at all Small, highly toxic, Asexual replication by representation No operculum or most derived strobilation Gastrodermal layer cnidocil cnidarians (Polyp strobilates in layers lacks nematocysts Coelenteron partitioned Medusa stage to release ramets [ephyra, by mesenteries (septa) dominates juvenile medusa]) Order Hydroida All marine Four tentacles or Marine Marine and Gametes produced by clusters of tentacles freshwater polyp planula (feeds near four rhopalia Thick mesoglea on phytoplankton and Complex, possibly Jellyfish Mesoglea is firm Rhopalia, manubrium, stuff like that) image forming eyes gelatin gonochronistic medusa Reproduce asexually by Polyp stage does not Medusoid with Shelf of tissue (velum) pedal laceration (cutting strobilate, polyp stage nematocyst studded increase propulsion off pieces of foot) as it buds more polyps that tentacles Stolon (connects GVC moves along slowly become ramets of different polyp Mouth opens into Anthozoa Subclass Mouth at the end of a polymorph), hydranth tubular pharynx and Hexacorallia muscular cylinder, the (oral end of a polyp) siphonographs (one or Possess tentacles and manubrium. Commonly encased in two discrete ciliated perisarc [surrounding grooves from pharynx mesenteries in multiples of six the hydranth = to mouth) Most are solitary thecate] Increase surface area Lack specialized Order Siphonophora for secreting digestive covering Well developed system of Free floating enzymes and absorbing fluid filled gastrovascular polymorphic colonies Never polymorphic canals, distributed among nutrients best known ones are Some have stony (true) corals that four gastric pouches nectophores for Mesenteries are either secret calcareous Also obtain nutrients from propulsion lack complete or incomplete zooxanthellae that live mouth and tentacles Free edge is trilobed, skeletons symbiotically in tissues Also called Pneumatophores filled ciliated and studded scleractinian corals (are Sensory organs: rhopalia with gas so they float with nematocysts, cells both reef-building and [statocysts, ocelli],sensory mesoglea absent that secrete digestive not) lappets distributed Modules within the enzymes, and others along margins of colony occur in Symbiosis with that phagocytose zooxanthellae drive the swimming bell clusters cormidia- bacteria reaction to make Gonochoristic (single arranged on a stem Contain longitudinal CaCO 3 sexed) medusae Phyllozooids bracts muscles and bear of nematocysts gonads Usually gonochronistic, Planula is nonfeeding, and but sometimes develops to a scyphistoma hermaphroditic (sessile, no sensory stuff) polyp Order Hydrocorallina Acontia are at the Subclass Octocorallia Polyp has thinner Colonial, secret CaCO3 bottom of the Tentacles and mesoglea skeleton mesenteries and can be mesenteries in eights Restricted to warm extended near the base Tentacles are pinnate waters for defense or offense bear numerous Dactylozooids Acrorhagi are little outfoldings called Polyp reproduces by especially abundant round bulges in rings pinnules budding, then creates and potent around the body just All form modular medusae by strobilation Not true corals below the tentacles col
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