intro to invertebrates tz sp15
Post on 13-Aug-2015
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Shared Animal Characteristics
Multicellular Most have tissues and organs
Aerobic heterotrophsReproduce sexuallyDevelop from embryosMotileToday we will focus on invertebrates
No internal backboneCompare similarities and differences
through several basic features
Symmetry
Radial symmetry: body parts arranged around a central axis
Bilateral symmetry: have a front and back end and right and left side
Embryo Tissue Layers
Zygote develops into a mass of cellsPrimary tissue layers form
Simple radial animals have two layers Outer ectoderm Inner endoderm
Bilateral animals have a third layer, mesoderm in the middle
Pattern of Development
Protostome: first embryo opening becomes the mouth Examples: flatworms, molluscs, roundworms,
arthropods
Deuterostome: second embryo opening becomes the mouth Example: Echinoderms, chordates
Body cavity: Coelom
Cavity between the gut and the wall that is lined with tissue Cushions organs Helps organs grow and move independently
3 types of body cavities
Acoelomate: no body cavity Flatworms
Pseudocoelmate: false cavity Partially lined Roundworms
Coelomate: true cavityHigher animals
Animal Phylogenetic tree
Sponges: Phylum Porifera
No true tissuesNo germ layersAcoelomatesNo symmetrySessile adultAsexual and sexual reproductionSpicules: made of different substances; for protectionCollar cells (choanocytes)-flagellated, create water
currentsAmoebocytes-digestion, secretionEpidermal cells-cover surfaceOsculum: largest opening for water
Grantia slide
Jellyfish Phylum Cnidaria
Radial SymmetryTwo germ layersSimple tissuesAcoelomatesPolyp and/or medusa stageStinging cells—Cnidocytes with nematocysts
Fluid filled capsule with thread
Nerve net
Hydra-cnidarian example
Look at slides and live specimens
Roundworms: Phylum Nematoda
Bilateral symmetryThree germ layers Molt their cuticlePseudocoelomatesCephalization with brainComplete digestive system (2 openings)Many parasites
Roundworm examples
Ascaris: intestinal parasite, infects humansTrichinella: encysts in human muscles
causing trichinosisVinegar eels: live specimen
Three germ layersCoelomatesBilaterally symmetricalJointed appendagesExoskeleton with chitinSpecialized segmentsCephalization
Phylum Arthropoda
Arthropod Lineages
Trilobites (all extinct)Crustaceans (crabs, shrimps, barnacles) Chelicerates (spiders, mites, scorpions)Uniramians (insects, centipedes, millipedes)Today: dissect a crayfish
Wear goggles, gloves, and lab coatsCarosafe safety proceduresPut specimens in correct containers
No gloves or paper towels with tissue waste
No unauthorized dissections-please treat specimens with respect
Clean all dissection equipment at conclusion
Important Dissection Notes
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