Hemichordata and Invertebrate ChordatesPhylum HemichordataSlide 3Class EnteropneustaMaintenance FunctionsSlide 6Nervous systemRespirationCirculatory systemReproduction and DevelopmentEvolutionary ties b/w hemichordatres and echinodermsClass PterobranchiaSlide 13Slide 14Slide 15Slide 16Slide 17Phylum ChordataSlide 19Subphylum UrochordataSlide 21Body wallSlide 23Slide 24Slide 25Subphylum CephalochordataSlide 27Maintenance FunctionSlide 29Slide 30Slide 31Hemichordata and Invertebrate ChordatesPhylum HemichordataBilaterally symmetrical. Body divided into three sections, a proboscis, a collar and a trunk. Characteristics of Hemichordata:-All live marine environments.Body cavity a truecoelom divided intothree cavities.Complete digestive tract, feeds on fine particles in the water. Dorsal, sometimes tubular, nerve cord.Class EnteropneustaBurrow in sandy and muddy substratesCiliated epidermis and glandscover acorn wormsMarine wormsCommon name ‘acorn worms’Maintenance FunctionsVentral MouthLateral Pharyngeal slits,few to several hundredCilia and mucus assist acorn worms in feedingCiliary tracts converge near the mouth and form a mucoid string that enters the mouthEnteropneusta extends its posterior end out of the burrow during defecation.Eww!!!Nervous system•Ectodermal in origin•Lies at the base of the ciliated epidermis•Consist of dorsal and ventral nerve tracts•No major ganglia•Sensory receptors are unspecializedRespiration•Simple diffusion of metabolic waste•Cilia associated with Pharyngeal slits circulate water into mouth and out of body•Gas exchange as water passes through pharyngeal slitsCirculatory system•Colorless blood moves nutrients and wastes•Dorsal and ventral contractile vessel•Blood moves anteriorly in dorsal•Posteriorly in ventral vessel•Branches from theses vessels lead to open sinuses (Partially open circulatory system)•Anterior flowing blood moves through glomerulus (excretory organ)•Waste filtered into proboscis coelom and out through pores found in wall of proboscisReproduction and DevelopmentDioecious!!External Fertilization pheromonesEvolutionary ties b/w hemichordatres and echinodermsCiliated larvaeClass Pterobranchiapteron- wing branchia- gillDeep marine waterSome live in shallow watersBody divided into three regionsSize 0.1 - 5mmIndividuals called zooidsMost live in secreted tubes in asexually produced coloniesMaintenance FunctionsFilter feedersCilia on tentacles trap and transportFood to mouthRespiration and excretory exchange by diffusionReproduction and DevelopmentAsexual budding is common and responsible for colony formationAlso some posses one or two gonadsMost species are dioeciousExternal fertilizationPlanula-like larva (cnidarian) Settles to a substrate, forms cocoon and metamorphoses into an adultPhylum ChordataCharacteristic of the chordatesDeuterostome embryo development Notochord, phayngeal slits or pouches, dorsal tubular nerve cord, and postanal tailCoelomate animalsBilateral symmetryEndoskeletonTwo major groups: nonvertebrate chordates and vertebratesSubphylum Urochordata•Uro, tail and chorda, cord•Class ascidians –Tunicates or sea squirts•Solitaire or colonial•Sessile adults•Attach to solid substrates•two siphons that permit seawater to circulate through the body •Oral siphon also the mouth•Atrial siphonBody wall•Tunic- gown•Connective tissue like covering•Tough secreted by the epidermis•Composed of proteinsSalts, cellulose•Stolons extensions of tunic help rootMaintenance Functions•Longitudinal and circular muscles below the body wall epithelium•Nervous system largely confined to body wall•Forms nerve plexus with a single ganglion between oral and atrial opening•Sensitive to mechanical and chemical stimuli around siphon but no complex sensory organsReproduction and Development•Tadpole larva•Attaches to substrate by adhesive papillae located below the mouth•During development internal structures rotate 1800 bending the digestive tract into a U-shapeReproduction and Development•Monoecious•Self fertilization and cross fertilizationSubphylum Cephalochordata•Elongated laterally flattened nearly transparent •Lancelets•Size up to 5 cm tadpole like animals•All four chordate characteristics persist throughout life•Shallow waters•genera Branchiostoma (Amphioxus)Reproduction and Development•Dioecious•Gonads shed gametes into the atrium •Leave the body through the atriopore•External fertilization •Bilaterally symmetrical larva•Larva free swimming•Larva Settle to substrate then metamorph into adultsMaintenance Function•Filter feeders•Buried in sandy substrate•Mouth pointed upward•Cilia on lateral surfaces of gill sweep water into mouth •Food sorted in the cirri •Edible particles move along cilia to the gut•No true heart•Contractile waves in the walls of major vessels propel blood•Blood contains amoeboid cells and bathes tissues in open spaces•Excretory tubules are modified coelomic cells closely associated with blood vessels.• Coelom reduced- restricted to canals near the gill bars, endostyle and the