differences between freshwater hydra and marine hydra?
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The difference between any organism's freshwater and marine counterparts are in homoestatic fluid balance.\n\nA marine hydra has a problem with maintaining enough water in its body. The salt concentration outside the hydra leads to diffusion of water outward. The hydra has to actively either take in water or remove salt (it does both).\n\nFreshwater hydra have a problem with having too much water in its body. Because there is more salt in the hydra than outside, water diffuses into the hydra. To maintain balance, the freshwater hydra actively transports water out of its cells.\n\nMany of these same issues can be said of freshwater fish and ocean fish, too.
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invertebrate\n\nmore info at\nhttp://www.ipm.ucdavis.edu/WATER/U/ceriodaph.html
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GO TO:\nhttp://aquarium.ucsd.edu/challenger/index.cfm
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This is what the larva looks like\nhttp://www.imagequest3d.com/catalogue/larvalforms/thumbnails/d004_jpg.jpg\nhttp://nai.arc.nasa.gov/library/images/news_stories/old/urchin_larva.jpg\n\nAnd these are the adults\nhttp://www.elasmodiver.com/BCMarinelife/images/green-sea-urchin.jpg\n\nI guess you can find several major differences.\nAnd I second the answer above :)
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Meroplankton is a type of zooplankton. Meroplanktons [larvae are planktons while adults are nektons or benthos] - Supraneutsons  use the surface tension of the water to walk over the surface. Their feathery appendages are also water replent. Planktons abound in estuaries, upwelling regions and are patchy in that they concentrated in zones of convergence.
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http://en.wikipedia.org/wiki/Hydra_%28genus%29
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ATLANTIC DEVIL RAY\nOrder - Myliobatiformes\nFamily - Mobulidae\nGenus - Mobula\nSpecies - hypostoma\n(i think this is the one u were asking about)\n\n I didnt know which animal u were exactly asking for. so check out the sites below
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Medusae is that of a jelly fish, Hydra is that of a coral!!!!
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Quick answer...one has a high salt content and the other does not.  Longer answer...when looking at salt and freshwater, it depends on the content of salt in the water.  Saltwater wetlands are usually along a sea or ocean, or along a tributary leading to them.  The salt content from teh ocean seeps up the river and hits the wetlands.  Freshwater wetlands are unsalanized and contain little or no salt.  This water supports freshwater fish and is a great watering spot for mammels and animals who need fresh (not ocean) water.
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DEFINITELY a dolphin, it is the smallest aquatic mammal. otters are not wholely aquatic. and sea monkeys sea lions etc are not mammals. whales are the largest mammals.
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The density is different - sea water being more dense than fresh.\n\nFreezing point (lower for sea water) and boiling point (higher for sea water) would be slightly different.\n\nElectrical conductivity would be different (higher for sea water).\n\nAll these things are different - but the differences are also all due to the salinity difference that you mentioned.
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Dear Hydra is part of our ecosystem and It is food of alots of organism and feeds upon microorganisms.Thus it plays crucial role in balance of very small water bodies.\nWe all learn basic principles of development and physiology with Hydra a model.It is also a model for studing regeneration.Finally it make you curious enough and you asked this question.
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http://images.google.com/images?q=nile%20crocodiles&ie=utf-8&oe=utf-8&client=firefox-a&rls=org.mozilla:en-US:official&sa=N&tab=wi
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go to howstuffworks.com search for hydralics they've got a great article on them
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Using Google Scholar I found at least one review of osmoregulation in marine mammals: \n\nhttp://jeb.biologists.org/cgi/content/full/204/11/1831\n\nAnd by using a few keywords, many articles come up. Try that :-)
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Cnidarians live mainly in marine environments. Examples of cnidarians are the jellyfish, sea anemones, and corals. They are different from sponges because sponges have assymmetry which means they have no definite shape. Cnidarians have radial symmetry.
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Good question!  You obviously know that glacial ice is not the same as frozen water in an ice cube tray in your freezer!  (glacial ice is compressed snow)  My initial response was that icebergs float, so yeah, it would float.  Then I thought that seawater is salty, which can cause more dense things to float and doesnt nescessarily provide a good proxy for a cup of drinking water.  Thennnnnn (you like following my train of thought here?) I remembered that icebergs calve into fresh water lakes, too and float.  So my long-winded non-quantitative answer is yes.  :)\n\nI have no idea if there is a difference in rate of melting, but my best guess is that it might take SLIGHTLY longer to melt.