Invertebrate Phyla for Bio (1) (1).pdf - PORIFERA - Sponges...

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PORIFERA-Sponges• most primitive multicellular animals• epithelial and connective tissues, but lack true organs• individual cells retain high degree of individuality• sessile• mostly marine,MK7000 species• body plan built around complex system of waterchannels2KOLMKRQNULK9SKOLWKVSRQJLK
±(4HVLRHXSLY°3 layers:1.Pinacoderm:- outer epidermis (skin)2.Mesohyl:- middle layer- amorphous, no firm cell structure- contains “amoebocytes” that candevelop into any other cell type(high regenerative ability)- spicules3.Choanocytes:- inner layer- flagellated cells- create water flow through sponge- responsible in feeding
Sponge skeleton• skeletal elements in mesohyl, can project to outside• spicules: calcareous, siliceous, protein fibers• shape of spicules important taxonomiccharacteristic• spicules secreted from cells in mesohylone sclerocyte required for each ray
Choanocytes and water flow• used in feeding:suspended particles get trapped at microvilli collarabsorbed into food vacuoles• respiration:O2-rich water reaches inner spongediffusion of O2into sponge, CO2released into water• excretion:metabolic waste (ammonia) released into water• reproduction:release of sperm into waterchoanocytes take up sperm and release itto eggs located in mesohyl
CNIDARIAentirely aquatic, mostly marine• ca. 10 000 living speciestwo forms: polyp and medusa• originally alternation between forms in life history• two epithelia:epidermis(skin) andgastrodermis(inner gut lining)radial symmetrywith oral and aboral side (mouth present butno anus)• in between both epithelia lies an amorphous layer:mesogloeamesogloea: water (90%) with mucopolysaccharides and collagenmesogloea aids in buoyancyserves as hydrostatic skeleton(locomotion: jet propulsion;movement of tentacles; bending of body; etc.)• some groups also with internal or external hard skeletons
General body plan Cnidaria• in life history: alternation between two body forms• polyp form reproduces asexually• medusa form produces sexually
Nematocyst structure and function• typical cell type for cnidariansstinging cells• used in defense and prey capture• concentrated in tentacles• nematocyst bursts open, triggeredby mechanical or chemical reception• thread shoots out and uncoils• hooks anchor to prey integumentthread uncoils inside prey• end of thread with toxins or glue• also used to entangle prey
1.Class Hydrozoa- alternation of polyp and medusa stage, often reductions/depressionsExample:life historyof9LOOLKsp.JLOLOHFSVFQT
2. Class Scyphozoadominant form is medusa“jellyfish”• polyp form small and inconspicuous• can be large in size (up to 2mdiameter)• manubrium short but long oral lobesumbrella usually with eightsegments,divided by sensorycomplex (rhopalium)• radial canals with multiple branches• gonads located in stomach

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Cnidaria

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