Lecture8ZooplanktonII

Lecture8ZooplanktonII - Zooplankton II You’ve met the...

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Unformatted text preview: Zooplankton II You’ve met the characters, now what DO they DO? Cliona limacina What do they do? • Eat • Avoid being eaten • Reproduce • Migrate • Defecate/excrete • Die • Sink Let’s Eat! Lots of water must be processed because the ocean environment is dilute (see below) so filtration of some form is usually involved…. – mucous nets : salps, larvaceans, pteropods – collect/pick particles using setae: copepods, euphausiids (krill) ________________________________ ________________________________ ___________________ SOME CHARACTERISTIC SCALES (values representative of coastal waters to an order of magnitude) organism linear dimension numerical density mm 3 m-3 (ppb) spacing in body lengths copepod 1 mm 5 liter-1 2600 6 cm 60 dinoflagellate 35 µ m 10 ml-1 225 5 mm 150 diatom 10 µ m 10 3 ml-1 525 1 mm 100 cyanobacterium 0.6 µ m 10 5 ml-1 11 200 µ m 350 bacterium 0.5 µ m 10 6 ml-1 65 100 µ m 200 virus 0.07 µ m 10 7 ml-1 2 50 µ m 650 Feeding by mucous net: • Salps strain water through a mucous mesh; feed best on particles > 1 μ m in size, but some smaller particles may stick to the net. • Larvaceans pump water through a mesh filter that is part of their house structure, provides a filter that keeps large (> 13 um) particles out; funnels carry flow of water to chambers, finer mesh filters inside work by “tangential flow” filtration, water exits tail. • Filter feeding pteropods don’t push water through a filter, they rely on particles sticking to a mucous feeding net that they extrude, hangs while it collects, then it retracts back into the body, discard it when it gets clogged. Larvaceans in house Cliona limacina (pteropod) Note that all these mucousy nets are a great source of carbon; concentration of particles will increase downward flux of C From Miller, Fig. 7.2 Anteriorly-directed setae form a filter basket (closed in (a), open in (b)). Fills from front when legs are opened, exopods control flow Crustaceans use a different approach…they collect or pick particles from the water – and they can be discriminating! Euphausiids use a “filter basket” made from setae; smaller and smaller projections creates screens beneath the body on either side; Food is shoved in mouth, ground by mandibular blades, ground again by “meshing” teeth in the crop Particle capture Dye stream Copepod feeding has been well studied…especially in Eucalanus and Calanus Koehl & Strickler, 1981 Antennae move apart, draws water towards mouth A particle is sensed, maxillae swing out to surround it and draw it between them Maxillae close and squeeze water out from around the particle http://www.uwm.edu/~jrs/ Feeding by Eucalanus pileatus , tethered Life at low Reynolds number...
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This note was uploaded on 12/14/2011 for the course BIOL 450 taught by Professor Ms.richardson during the Fall '10 term at South Carolina.

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Lecture8ZooplanktonII - Zooplankton II You’ve met the...

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