Kingdom AnimaliaAnimals are multicellular heterotrophs, and usually mobileFood is usually ingested and digested in an internal cavityDiversity in formMost are invertebrates - Only 1% of all species are vertebrates37 animal phyla (10 to be covered in these lectures)Size ranges from microscopic forms to enormous whalesMost are marine, some are freshwater, few are terrestrialThree phyla dominate the land: arthropods, mollusks, chordatesAnimal cells lack cell walls - their cells are relatively flexibleCells are well organized into tissues, except for spongesTissue: made of cells specialized to perform specific functionActive movement - made possible by muscles - flexible contractilecells combined with rigid resistant structures - a hard skeletonor incompressible water-filled spacesSexual reproductionAll animals have gametic meiosis - a diploid organism produceshaploid gametes by meiosis in specialized tissuesEmbryonic developmentZygote becomes an adult through process of embryonic development - organization and differentiation of tissue layersPattern of development important in determining evolutionaryrelationshipsClassification of AnimalsSubkingdom Parazoa - the SpongesSubkingdom Eumetazoa - all animal phyla with true multicellularity -well developed tissuesRadiata - phyla with radial symmetry, two tissue layers(Phylum Cnidaria and Phylum Ctenophora)Bilateria - all remaining animal phyla have bilateral symmetry andthree tissue layers: ectoderm, mesoderm, and endodermMultipleplanes ofsymmetryOne plane ofsymmetryWithin the Bilateria there are types of tissue organizationCoelom: a body cavity lined completely with mesodermAcoelomates haveno body cavity -flatwormsPseudocoelomateshave a body cavity(pseudocoel) withmesoderm to theoutside only -roundworms androtifersCoelomates have a coelom - all remaining animal phylaWithin the coelomates there are two ways that embryonicdevelopment occursProtostomes have spiral cleavage, the blastopore becomes themouth, mosaic development - molluscs, annelids, arthropodsDeuterostomes have radial cleavage, the blastopore becomes theanus, regulative development - echinoderms, chordatesSignificance of characteristicsBilateral symmetry allows for greater specialization of body regions- a head, midbody, and tail - have different functionsmore efficient locomotiona head with sensory structures and coordination of the nervoussystem - cephalizationA coelom can be used for storage of energy rich compounds ( fat)reproductive products – eggs, sperm, embryosOrgans can develop with separation from other tissuesAllows for specialization of regions of the digestive systemWater filled space that can be used to move body partsAllows for circulation of fluids around organsPhylum Porifera - SpongesMostly marine, few freshwater species,most lack any symmetryThree basic shapes - ascon, sycon, leuconMany are colonial, all are sessile as adultsLittle coordination among cellsSimple mass of cells in a gelatinous matrixCells are specializedChoanocytes - collar cells - for feedingEpithelial layer of flattened cells, frequently contractile in natureAmoebocytes - found in Mesohyl - intermediate gelatinous layerMay possess minute, needles called spicules made of silica or calciumMay possess fibrous protein “spongin”Filter feedersWater flows through system of pores and canalsIn through pores (ostia), out through osculum, passageways linedwith choanocytes capture food and pass it through to other cells inthe sponge bodyReproductioncan fragment and reorganize for asexual reproductionSexual reproduction via production of egg and spermSperm differentiate from choanocytes and leave spongeeggs differentiate from amoebocytes in mesohylSperm are captured by choanocytes and taken into mesohylLarval sponges undergo development within adultsHave external choanocytes when releasedExist as free-swimming planktonic form for a short timeSettle on a suitable substrate to begin transformation to sessileadult liferadial symmetryhave endoderm and ectoderm but no mesoderm or well developed organsCarnivores, capture food with tentacles that surround mouth using specialized stinging cells - “cnidocytes”No blood vessels, No respiratory system, No specialized body cavity,Nerve cells organized into nets to coordinate muscle contractionHave two body forms - polyp and medusaPhylum Cnidaria – jellyfish, hydras, anemonaes, coralsnearly all are marinePolyp: cylindrical, tentacles surround mouthgenerally attached to substratesolitary or colonialmay form hard internal or externalskeletonMedusa: bell-shaped, tentacles atedges of “bell”free-floating, mouth faces downSome groups have only polyps oronly medusaeSome groups alternate between thetwo body formsSometimes called “alternation ofgenerations”An internal digestive cavity enables cnidarians to consume largefood itemsenzymes secreted into a primitive gut begin digestion Particles digested further by cells of gastrodermis Undigested food particles expelled from gut through mouthCnidocytes are cellsspecialized forfood capture anddefenseLocated on tentacles and bodyEach cnidocytecontains a harpoon-like nematocystthat dischargeswhen touchedReproductionPolyps reproduce asexually by budding, form polyps or medusaeSexual reproduction produces fertilized eggsDevelops into a free swimming, ciliated planula larvaClasses of CnidariansClass Hydrozoa - HydroidsClass Scyphozoa - JellyfishClass Anthozoa - Corals and AnemonesClass Cubozoa - Box JellyfishClass Hydrozoa - HydroidsMostly marineOften have both polyp and medusa formsin life cyclesome colonial forms like ObeliaOthers include Portuguese man-of-war and freshwater HydraClass Scyphozoa - JellyfishConspicuous medusae alternatewith inconspicuous polyp formsMedusa is bell-shaped, tentacleshang around marginsOuter epithelial layer containscontractile cellsSex produces planula larvaePolyps can reproduce asexuallyClass Cubozoa - Box JellyfishOnce included within Class ScyphozoaMedusa is box-shaped, polyps are inconspicuous or unknownTentacle found at each corner of boxStrong swimmers, voracious predatorsMany have powerful stings - some can be fatal to humansClass Anthozoa: Sea Anemones and CoralsSolitary and colonial marine organismspolyp body form onlyCorals secrete hard calcium carbonate skeletons and form coral reefsLive primarily in shallow warm waters, harbor symbiotic algae - “zooxanthellae”Waters that support corals are nutrient poor - corals do well because of algaePhylum Ctenophora -