Chapter 33: EcdysozoansA. Phyla Nematoda (roundworms)Colorless round body with tapered endsWith thick flexible cuticle (outer coat) that is shed as it grows; made of collagenGood for studying; developmental biology because it’s a protostomeWell developed digestive tractWhip like motion, contracts opposite longitudinal musclesPseudo-coelom fluid distributed nutrients from gut to entire bodyDistinctive thrashing movementNo circulatory systemMost widespread of all animals; can live anywhereMost important free-living decomposers in soilParasites in plants and animalsWheat rootsTrichina worm-under cooked porkFilarial worm- elephantiasisB. Phyla OmychophoraAncient group close to athropodaFlexible cuticle with chitinSegmented, but legs are soft and un-jointedUsed to be marine in Cambrian eraNow we only have terrestrial, only in tropical forestsSquirt out sticky goo to trap organisms then poison itC. Phyla TardigradaSegmented with stubby lobe like legsVery small (<.5 mm)Mostly colorlessPiercing mouth pieces, feed on cell fluidsLive in water films on plants and soilsFamous for living in dormant state years without water, 2% water in cells SURVIVE IN SPACE!!!!!D. Phyla AthropodaSegmented body with hard exoskeleton and jointed appendagesAllows for more movementSegments are highly specializedCuticle made of chitin and proteinsAdditional waxes prevent water lossCalcium carbonate in marine arthropodaSupport protection and attachment of musclesLimits body sizeMust be shed to grow; costs energyOpen circulatory systemHemolymph= fluid pumped in vessel and bathes tissuesUsed to move nutrients and wasteUses spiracles to move oxygenGas exchange varies:Aquatic species: hymolymph pumped through feathery gillsSpider’s book lungs exchange gases in air with hemolymph (in chamber to be kept moist)Insects: separate tracheal system for gas exchange at cell level (branched into cells and air sacs)TrilobitesEarly marine group, all extinctHighly diverseMany simple appendages and segmentsMouth under flapCheliceraeChelicerae for feeding (spiders with poison)Body plan: cephalothorax and abdomenNo antennae, simple eyes (multiple)First chelicerae were marine/fresh water: eurypteridsWater scorpions (not scorpions)Major predators (variation in size)2 aquatic groupsSea spidersHorseshoe crabs- scavengers, cell biologyMost are arachnidsLand predators or parasitesFour walking leg and one pair feeding appendages (pedipalps)Include scorpions and spidersBrown recluse-hemotoxinBlack widow- neurotoxinSpiders only organisms to catch prey with silkIncludes ticks and mitesVinegaroon- spits vinegar at you (not scorpion)Camel spider (not spider)MyriapodsMany identical segments and legsMandibles for feeding; 1 pair antennaeAlmost jawsMillipedes are scavengers2 pairs of legs for each segmentSome secrete cyanideCentipedes are predatorsHexapodaExtremely successful on land; many in freshwater1st animals to flyWings derived from cuticle extensionsAnatomy:Body has three parts (head, thorax, abdomen)Thorax has 3 pairs of walking legs, 0-2 pairs of wingsHead with 1 pair antennae, compound eyesMandibles for feeding (adapted for piercing)Complex organ systems including unique malpighian tubules for excretion of metabolic wasteDiverse feeding habits/ecological rolesHerbivores, predators, parasites, decomposersSome with complex social systemsQueen bee, sisters, jobsTermites are socialLand-adapted reproductionMetamorphosisIncomplete: stinkbugComplete: butterfly, aquatic insectsHuge ecological impactPollination for cropsInsect damage of cropsAnimals depend on insectsCarry diseasePestsScience for experimentsCrustaceansMostly marine; some freshwater, some landMost are predators/scavengersHave branched legs on thorax and abdomen2 pairs of antennae, feed with mandiblesIncludes lobsters, shrimp, crayfish, krill, crabs, barnacles, water-fleas, copepods, pillbugs, sowbugsE. Phyla EchinodermataPente-radial symmetry as adultsReflected lifestyle of cnidariansNo head, no brainOral/aboral side; central mouthA. CraniatesHave a headCranium holds brainPaired sensory organsNeural crest cellsGive rise to parts of skull and more [34.7]Skull bones/cartilage creationGills have muscular supportHeart with 2-4 chambersClosed circulatory systems with hemoglobin in blood cellsMyxini (hagfish)Eel like marine scavengersChemosensory organsNo fins, skull of cartilage, no jawsNo vertebrae, use notochordB. VertebratesMost aquaticCraniates with vertebrates enclosing spinal cordsReplace notochord as main body support1st made of cartilage, then boneDorsal, ventral, and/or tail finsSupported by fin raysEarly vertebratesAll jawlessLater jawless fish with bony armor platesPetromyzontida (lampreys)Most basal vertebratesCartilageJawless parasite on fishSucker like mouthC. GnathostomesJaws, usually with teethLike derived from gill slitsLarger forebrain (smell/sight)Paired lateral fins/limbsUsually 2 pairPectoral and pelvicLateral line system for aquatic speciesPick up pressure movements of prey/enemyPlacoderm: early jawed fishBony armored skin ~450 million years agoHuge head ~ 1 meterLater fish with mineralized bones3 lineages:1) Cartilaginous2) Ray finned3) Lobe finnedChondricthyes (sharks, ray, kin)Skeleton mostly cartilage (derived)Bony teeth and scalesLost boniness because of buoyancyMost are active predatorsInternal fertilization, development variesOviparous: egg laid, embryo develops within eggOvoviviparous: egg in mother, live birthViviparous: embryo fed directly by maternal tissue, live birthOsrerchthyes (bony fish)Paraphyletic group (omits tetrapods)Aquatic gnathostomes with ossified skeletonCalcium phosphateSwim bladder provides buoyancyDerived from lungs used to gulp air in oxygen poor shallow waterDorsal to digestive tractFlat scales and slime protect and reduce dragOperculum gill coversUsually oviparous, external fertilizationActinoptergii (ray fish)Thin fins supported by thin flexible raysMost diverse groupBoth in marine and freshwater areasHerbivores, predators, and scavengersAlmost all bony fishSeahorses, lionfish, eelsLobe fin fishPelvic and pectoral fins supported with bones and musclesActinista (coelacanths) [34.19]Dipnoi (lungfishes)Gulps air into lungs in stagnant pondsD. TetrapodsEvolutionCharacteristics4 limbs with digitsNeck (way to rotate head independently)Pelvic girdle fused to backbone (lifts body up off the ground)Lung breathing as adultsLobe fin fish line to 1st tetrapodsTiktaalik fossil [34.20] was freshwater fish with tetrapod like featuresFlat
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