phylum arthropoda - west chester...
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Phylum Arthropoda
Arthropod Characteristic= “jointed limbs”Segmented body = metamerism= grouped into 2/3 regionsPaired segmented appendagesChitinous exoskeletonTubular alimentary canalCoelom reduced to hemocoelOpen circulatory systemRespiration by gills, tracheaeor spiraclesAnterior ganglion, pairedconnectives & nerve cordsMalphigian tubes = excretionSeparate sexes
Arthropod Fun FactsAphids are born pregnantNo two spider webs are alikeAdult bed bugs can survive 1 yearwithout foodHornet sting has highestconcentration of AChEBed houses 6 billion dust mitesAnt queen can live 15 yearsDragon flies can reach 60 MPHEach year insects eat 1/3 earth’sfood cropCitronella irritates mosquito feetMosqitos prefer children toadults, blondes to brunettes
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Arthropod Fun FactsLobster blood = blue, insect =yellowFlea leap = greater accelerationthan space shuttleBlack widow venom morepowerful than rattlesnakeParasitic wasp = smaller thanhousefly eyeMore insects in 1 mile2 thanhumans on earthHoneybee kills more people thanpoisonous snakesAmong the deadliest insects arekissing bugs and African ants
Arthropod Generalized Bauplan
1. Longitudinal viewThree distinct sections or tagmata: head, thorax andabdomen (different classes have slightly different names)Head = antennae, mouthparts, tightly fused = cranium =difficult to determine # of segments involvedThorax = locomotor part of the body, three segments(often fused)Abdomen = may or may not contain appendages
Arthropod Generalized Bauplan2. AppendagesLack ciliation formovement = evenduring larval stagesProblem = rigidexoskeletonSolution = appendagesof plates andcylindersSkeleton + muscles =leverageAdapted for differentfunctions on types oflocomotionUni- or biramous
Arthropod Generalized Bauplan
3. Cross sectionLoss of coelom associated with open circulatory systemHemocoel = internal organ are bathed in body fluidsBody size demands pumping organCephalization, ganglions due to metamerism
Arthropod Generalized Bauplan
4. Exoskeleton= secreted by epidermal cellsEpicuticle = outermost, hard protein cross link, waxylipoprotein (cement layer, waxy layer and cuticulin)Procuticle = bulk of exoskeleton, made of exo-andendocuticle, flexible, composed largely of chitin,strengthened by calcium
Moulting or EcdysisInvolvement ecdysone (hormone)
a) Old skeleton detached fromepidermis
b) Epidermis secretes epicuticlec) Enzymes degrade exoskeletond) Secretion of new procuticlee) Old skeleton splitsf) Extrication from old skeletong) “Sclerotinization” = tanningh) Some animals consume old
skeleton
Generalized Bauplan Differentiation
Subphylum Cheliceriformes
Cheliceriformes Characteristics65,000 described speciesSome paleozoic forms were2 m lengthRich fossil recordMost species live on landMites secondarily inhabitedaquatic habitatsBody composed of:Prosoma = cephalothorax (6segments)Opisthosoma = abdomen (12segments)! bearing telsonBook lungs or gills
Cheliceriformes CharacteristicsAppendages: chelicerae,pedipalps, walking legs= multiarticulate/uniramousExcretion by coxal glands/Malphigian tubulesSimple medial eyes,sometimes compund eyesMost gonochoristic/dioecious
Class Chelicerata
Subclass Merostomata
1. Carapace2. Telson3. Compound eye4. Anterior spine
Preserved specimen ofLimulus polyphemus
Called horsefoot by Thomas HariotHarmless and non poisonousTelson used as lever or rudder
Asian horseshoe crabs = delicacy (up to $50/animal,American horseshoe crabs = bait ($1-2/animal)
12
3
1. Chelicera2. Pedipalps3. Walking legs4. Chilaria
1. Genital operculum (covering genital pores)2. Gill opercula (covering book gills)3. Carapace5. 4th chelate walking leg
Ventral view ofabdomen of Limulus.
Hemolymph = analogous to human bloodOxygen carrying protein = hemocyanin
Whelk fishermen use 20-25,000horseshoe crabs annually as bait
Breeding grounds = Delaware Bay
Subclass ArachnidaCarapace-like shieldOpisthosomaappendages modified= spinnerets/pectines
Book lungsAlmost all terrestrialOver 60,000 speciesCarnivorousEyes and tactile hairs
1
2 3
1. Eyes2. Cheliceraewith fangs3. Pedipalps
Spinnerets
The “Joy” of Spider ReproductionGonochoristicSexual dimorphism
Intricate mating duels(other males)CourtshipSperm deposited in webFertilized eggs in silkcocoon
Spider Art
Class Pycnogonida= sea spiders600 speciesCarnivoresDt extendsinto legsCold water
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