Andrew is a freelance marine biologist in North Carolina focused on population and conservation genetics in hydrothermal vent communities.



David is a graduate student in Florida. He studies the ecology and conservation of sharks.




Amy is a graduate student in North Carolina studying local ecological knowledge within small scale fisheries.



Chuck is a graduate student in North Carolina focusing on apex predators and how they interact with fisheries.




Lyndell is a graduate student in North Carolina, studying the feeding ecology of cownose rays.




Iris is a graduate student in Washington studying habitat use and feeding habits of juvenile Pacific salmon and herring in Puget Sound.



Michael is a graduate student in Maryland investigating the visual systems of mantis shrimp.



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Urea and Shark Osmoregulation

One of the challenges inherent in a marine lifestyle is in maintaining an internal balance against external osmotic pressures. Cell membranes are permeable to water, and water tends to flow from areas of low ion concentration to areas of high ion concentration (which is called ‘osmosis’). Though the cell is incredibly complex, from an osmotic perspective it is basically a small sack of water with some ions in it. If cells aren’t isosmotic (i.e. containing the same  concentrations of ions) to the surrounding environment, then water will flow across a cell membrane. Depending on the relative ionic concentration of the cell to the environment, water may flow either into or out of a cell. Either way, this water flow is bad for the organism and may result in cells shriveling up or bursting.

Image from PhSchool.com

Continue reading Urea and Shark Osmoregulation