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Biology 3229F/G Midterm: Animal-Diversity-Midterm-Review

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Biology 3229F/G
Graeme Taylor

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Animal Diversity Midterm Review Phylum Cnidaria - Ancestral, not derived, primitive, simplistic in design - No invertebrate or vertebrate (no common ancestor shared) o Humans have Bilateral Symmetry - 11,000 species o Anthozoa, Scyphozoa, Cubozoa, Hydrozoa - Cambrian explosion is an example of adaptive radiation at the phyla level o Don’t know how groups are related after the explosion and length of time - Exam: What is a cnidarian *9 characteristics that define the group o Best characteristic is the cnidae – complex cell in animal kingdom that harbours a harpoon like structure - 4 Classes within Cnidaria, all share 9 traits that unify them o Radial symmetry – primary body axis is oral-aboral o Gastrovascular cavity – only body cavity, called coelenteron o Diploblastic – ectoderm and endoderm separated by mesoglea (snotty stuff – ectodermally derived – acellular) o “Simple net” NS – composed of naked and large nonpolar neurons  Start seeing concentration of NS in active cnidarians o Without head, centralized NS, discrete gas exchange, excretory or circulatory structures  Only 2 tissue layers - thin and in proximity to the environment – exchange gas and waste and stuff  Allows for their size o Epitheliomuscular cells – formed from ectoderm and endoderm (adult epidermis and gastrodermis)  Muscle tails connected to mesoglea? o Cnidae – stinging/adhesive structures – resides in a cell – cnidocyte  Most common cnidae are nematocysts  Tentacles wrap around you and cell fires harpoon and injects neurotoxin into body – thousands of injecting harpoons  30 different types  Cnidocil (stinger) can be stimulated by mechanical frequencies throughout the water  Force = 40,000g o 2 forms – alteration of generations – polyps and medusa  Dioecious (separate sexes)  Planktonic, form blooms and release sperm and egg in water to give rise to planula larvae  Swims through cilia o Planula larvae – ciliated, motile, gastrula larvae  Ciliary movement in medusa as well - Cambrian Explosion o 600 million years ago o Forms of the animals occurred so rapidly o Was it the oxygen levels? Was it gradual or quickly? We don’t know - Class Anthozoans – generally all marine - corals o Solitary or colonial o Medusa stage absent o 6000 species o Thick and well developed column o Circular MT DNA o No operculum and cnidocil o Ciliated siphonoglyph (extends into pharynx) o Mesenteries/septa in coelenteron o Order Scleractinia – true corals  3600 species – largest taxon  Majority are colonial  Small polyps (1-3mm diameter – 100,000 polyps)  Calcium carbonate skeleton  Polyp sits atop  Reef builders (hermatypic) have zooxanthellae  Colour from this algal partner – white is unhealthy – bleaching  Can form mucus layers over tissue – stick organic particles to mucus and drag though ciliary action  Diploria labyrinthiformis – Grooved Brain Coral  Slow growing  Acropora cervicornis – Staghorn Coral  Fast growing  Hit hard by climate change and increased hurricanes o Order Pennatulacea – sea pens & sea pansies  Bilateral symmetry  Single, long axial polyp with smaller polyps on side branches  Anchors in soft bottoms  Broad surface into current to capture prey  No medusoid stage  Adult is polyp – gametes are made from polyp  Circular and longitudinal muscles  Disk attached through some nematocyst – can get up and move o Asexual Reproduction  Longitudinal or transverse fission  Segmentation of body  Pedal laceration  Small pieces of pedal disk breaks off into smaller anemones  Fragmentation in corals o Acontia  Thick filaments in the coelenteron  Loaded with nematocysts and secretory cells  Can be extended outside body through pores in body wall  Defend and attach (also digestion)  Acrorhagi – competing for territory or space - Class Scyphozoa o Medusa is the dominant stage in the life cycle  Polyp stage is reduced o 200 species – all marine – many large – many colourful  Discovering more as we explore mesopelagic zone  Gastrovascular canal (extension of gut) throughout body – lined with cilia – in essence their circulatory system  Middle is the manubrium – off of that oral arms  Robust mesoglea – mainly the skeleton o Medusoid Locomotion  Very simple in design, successful for a long time  “Swimming bell” and stomach  Epidermal musculature developed  Sheets under the bell  Circular muscle contracts and closes bell – forces water out in a bolus – propelled forward – bell must come back and motion is stalled  Drifters – strong ocean currents move them around  Vertical travel – up and down to avoid predators o Around edge of medusa are sensory organs known as rhopalia  Light cell organs made of pigment spot ocelli, statocysts and pigment cup ocelli (primitive eye spots) o Gonads develop from endoderm – typical tell between male and female o Pelagia  Lifecycle occurs entirely in the pelagic environment o Aurelia  Exploits the pelagic environment  Dioecious adult – giving rise to polyp in a cave (scyphistoma) and undergoes “weird thing”  Asexual and referred to as stobolation (so it strobolates) – gives rise to these little tiny jellys known as ephyra (immature medusa) from its strobilus - Class Cubozoa – box jellyfish o Evolution has been “driving” the box jelly into complex structures o Medusa is four sided – single or cluster of tentacles at each corner  Key difference from Scyphozoa – presence of Velum in medusa (skirt) o Incredibly complex eyes – up to 24 eyes/pigment cups  Or have an eye with cellular lens and retina  Could have nervous cluster to that eye so they can resolve an image or utilize it to see if its being attacked by something larger o Tripedalia  Short-lived polyp phase  Cubozoan polyp does not strobilate  Buds off single medusa then dies o Chironex – Sea Wasp  Nematocyst sting is sufficiently painful beaches close when present - Class Hydrozoa o Mostly marine in shallow and deep environments o Somewhat thick mesoglea but lack cells o Gastrodermis lacks cnidocytes o Gonads epidermal o Small medusa with velum (skirt) o Polyp more complex o Most diverse in terms of their complex life history  Hydra is a specialized polyp  Fresh water so it doesn’t have the water movement  Harbour developing embryo?  Adult female, egg and sperm, zygote  Specialization of the medusa stage  Free-swimming actinula larvae  Specialized reproductive polyp – defensive and feeding polyps  Start to see specialization o Colonial Hydrozoans  Portugese man-of-war  Floatation device full of gas – utilizes wind to send across oceans – uses as a sail  Long tentacles act as a net  Polyp stage, not a medusa o Modified into specialized structures o Gastrozooid is involved in feeding o Dactylozooid defensive for attacks  Gonophore for reproduction  Pelagic organism that is colonial  Can grab onto fish, fill with venom to paralyze, and take prey into mouth – consequences for swimmers Hydrozoa, Scyphozoa and Anthozoa summary at end of Lecture 2 Phylum Nematoda – The Round Worms - Large, many unidentified, pseudocoelomate phylum including plant and animal parasites as well as free-living worms - Most abundant organism on planet*** o Root tissue, leaves, grasses, creeks, oceans, shallow water, mines o Biggest one – 9 meters in a whale uterus o 1 million/meter in freshwater benthos o 4 million/meter in marine benthos o 90,000 in a rotten apple - Annelids have clear head – nematodes taper in both ends - 2 billion people are infected with nematodes – low sanitation o Ascaris (pig parasite)– infective stage is the egg – quite resistant to treatment, bleaches or even some preservatives o Females produce 200,000 eggs a day o No real excretory system o Ascaris is a large whale relative to other nematodes o Loa Loa worms – infect eye - 16-22,000 described – actual number closer to 100,000 to millions o Primarily parasitic, but many different niches - Bauplan of Nematoda o Homogenous morphology o ‘Worm’ form – long and tapered at both ends o Bilaterally symmetrical (except anterior region) o Mouth terminal – with 3 or 6 lips o Cellular or syncytial tissue o Species specific number of cells o Mostly no cilia (some have ciliated gastrodermal cells) - Musculature, Internal Pressure and Locomotion o Circular and longitudinal muscles – alternating contractions  Sinusoidal waves o If worm has citae or apendages with those segments it has something to move along o Syncytial in parasitic form o Permeable, quite thin and flexible o Have to live in aquatic or moist terrestrial environments o Longitudinal and circumferential arrangement of fibers  No mobility allowed – fibres do not extend o Spiral arrangement of fibres allows length and diameter change without change in volume o Success due to protective cuticle from harsh environments  External cuticle layer  homogenous layer  3 fibrous layers  Basal lamina  Under high pressure (gives them roundness) cuticle structure acts as skeleton - Eggs hatch as small nematodes o Cuticle means it has to molt in order to grow o Continuously grow – molt period represents plateau event o 4 moult stages as they develop to the adult form - Epidermis arranged in 4 fields o Dorsal nerve o Longitudinal muscle o Excretory canal o Ventral nerve - Myoneural system o Unusual – rather than motor neurons running from the nerve cord to the muscles each muscle cell extends a process to the nerve cord - High internal fluid pressures o 70mmHG Ascaris – between 16-225mmHG in other nematodes o Tends to collapse the gut o Pharynx acts as a muscular pump concentrating food and forcing it back into the gut o Pharynx opens, draws in food, makes bolus, moved back through a valve into the intestine Phylum Porifera – The Sponges - Found in fresh water - Dried sponges are the skeleton of the animal – spongent fiber - Solitary and colonial - Diverse shape and colours – mostly “chimney” at top o Osculum – chimney hole - Some eat organisms, others have symbiotic relationships - Mostly eat small organic nutrients, bacteria, etc. - Colourful near upper regions of benthos, lack thereof in deep water - Colours have to do with symbiosis with algae or bacteria - Hard skeletons o SiO o2 CaCO 3 o Hard skeleton of spicules o Dolphins use sponge on nose as protection from sand - Soft skeleton of sponging o Collagen polymerized to thick fibers o Clastic – huge variety in shape as opposed to being fixed - Archaeocyatha o Evolved during the Precambrian o Good fossil record 1000 genera o 20% still extant o Sponge has no nerve net (cnidarians) but does show coordination - Classes of Porifera o Calcarae  Calcareous spicules  Lack sponging  Small (<15 cm) o Demospongiae  Silica spicules  Some have sponging  Most successful group of sponges  Can be large (>2m) o Hexactinellida  Silica spicules Lack sponging  Very odd, deep sea taxon  10-30cm o Homoscleromorpha  Lack spicules (some silica)  Distinct basal membrane (clear and under epithelium)  Epithelial cells bear cilia - Flow Rates o Steven Vogel (1974) measured flow rates In situ in Bermuda - The Sponge Pump o Pumps a volume of water equal to its body volume every 5 seconds o 1L sponge pumps about 720L of H2O in one hour  3x as much as a human heart  Human heart (vol 0.28L) pumps 280L in one hour o Lack true muscle and nerves, how do they pump?  Sponge lives in a world of flowing water  Water flows by the sponge and enters through pores  Water currents moving overtop create a negative pressure at the top of the chimney, that draws the water back out  Active and passive movement of water through a sponge  Choanocytes  Villi move 360 degrees like helicopter  Collar flagellated cells  Beat and move things around - 1L volume sponge = 400 million ostia (ostium = pores) - Sponge design o Water is incompressible – volume in equals volume out o Ostia added up the cross-sectional area is much greater than the Osculum – creates Jetstream through that o Wall contains choanocytes and flagella – increases the area itself by slowing water down to extract food particles - Evolutionary trends in body plan Asconoid Syconoid Leuconoid o Asconoid  Simplest, single chamber, spongocoel lined w/ choanocytes o Synconoid  Intermediate, multi-chambered, radial canals lined with choanocytes o Leuconoid  Complex branched canal system, multi-chambered, choanocytes in small spherical chambers o Amazing thing about the sponge – few cell types work together (20)  Porocyte with ostium – cross the boundary  Pinacoderm (pinacocyte) – if this was a true tissue layer it would have a basal lamina with it  No true connections between cells on surface – loosely associated – would need cell junctions  Archaeocytes float freely in mesohyl  Ability to transform, highly plastic in morphological design  Spicules from archaeocyte cells - Mesenchyme cells secrete the sponge skeleton o Spicule formation – scleroblast o Spongin formation – fibroblasts - Anatomy-ish o Osculum can close up using contractile cells  Encircle oscula – can open and close in response to environmental stimuli - Sex and Development o Asexual reproduction through budding o Also sexual – male sponges release clouds of sperm – enter ostia o Hermaphroditic – sequential  One day they’ll have the egg, next day have the sperm o Internal fertilization  Egg is held in tissue of adult sponge (mesohyl)  Engulfed by choanocyte cells  Egg engulfs sperm thing?  Takes some sorta DNA thing?  Zygote formation o Develop into larvae  Amphiblastula larva  Many types – interesting developments in group as a whole  Ball with cilia/flagella on the outside (larva) o Find suitable substrate and metamorphose into a young sponge where the flagella are then internalized  External used for moving  Choanocytes used for eating now - What is required to become a multicellular organism? o Cell recognition systems, o Cellular adhesion systems, o Elaboration of a matrix or connective tissue, o Skeletal systems to permit increase in size o Feeding, reproduction and dispersal mechanism Phylum Annelida – Ringworms - 16,500 species - Can get up to 3m, not as large as parasitic nematode (still quite large) - Meiofauna – group of organisms that live in the interstitial spaces of sand or soil - Serial homology – true segmentation – units are homologous to one another - 3 Classes (ordered least to most derived) o Polychaeta – least derived (not terrestrial) o Oligochaeta - earthworms o Hirudinea – leeches (false segmentation) - Smooth outer tissue – cuticle – soft and squishy with rings - Clatelium – fatty tissue in reproduction (band on worms) - Giant earthworms in Australia live in water filled burrows o Enormous egg cocoons – direct development (indirect in polychaeta) - Ectoparasites – live in water – suckers at both ends - Terrestrial in areas where it’s heavily moist – difficult controlling moisture - Leeches used in Europe for medical purposes – anti-coagulant properties - Spaghetti worm o On the sides are parapodia (or setae) that come out from each segment o Worms are sedentary (burrow) – setae grip onto substrate or act as respiratory organs o Active ones have full parapodium used in locomotion - Metamerically segmented coelomates o Coelom is a schizocoel  Secondary body cavity (primary is blastocoel) o Each segment refers to a coelomic cavity o Homonomous – segments are repeated and similar o Heteronomous – marine polychaete – shows extreme specialization of each of the segments - Differentiated Head o Clearly differentiated head with numerous sensory structures  Tentacles, palps, eyes, cirri, parapodium - Class Polychaeta o Lives in a burrow o Forms a mucus bag repeatedly  Piston like things to drive water through the burrow and allows it to filter particles – eats the mucus bag full of food o Pharynx of many has, when fully everted, jaws for prey capture o Bloodworms have 4 jaws – each with duct opening for venom o Many active have eyes - Annelid eyes o Pigment cup – shadow detection o Lens + Pigment cup = movement detector?  Pelagic polychaeta with eyes capable of forming images - Well developed CNS o Paired cerebral ganglia o More active polychaetas have a fore brain and hind brain o Circumoesophageal nerve ring, sensory nerves o Double ventral nerve cord (can be fused) o Ganglion will form at each segment o Ventral nerve cord includes giant neurons  Runs through segmental ganglia without making frequent synaptic contacts o Why have giant fibers?  Faster electrical transmission  Small = 0.05m/sec Giant = 10-20m/sec  Instantly tells if somethi
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