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Shark Osmoregulation

Submitted by mtracy on Fri, 09/21/2018 - 23:58


Sharks are osmoconformers. That is, they actively regulate their internal salinity to match the salinity of their outside environment. In most organisms the kidney regulates internal salt levels. While sharks have kidney’s there is an additional organ which aids in their salt regulation, the rectal gland. The rectal gland receives hormonal inputs, mainly from Angiotensin-II and 1-a-hydrxicorticosterone (1a-OHB), the latter of which is only found in Elasmobranchs such as sharks and rays. When receiving these signals, the rectal gland will shut off blood flow and retain osmolytes, which contain solutes. Through this process, a shark may match its environments salinity, perhaps even exceed it which allows it to take in water easier when in a salty environment. This also means a shark may enter fresh water, though it will need time to accumulate since regulation takes time and does not occur immediately. Due to this ability to osmoconform, sharks can populate a variety of environments. On several occasions, sharks have even swam up a large rivers such as the Amazon or the Mississippi river. Sharks have even been spotted as far up as Chicago, a long way from the ocean.



i liked how you let know the reader how sharks have the ability to live in different environments such as common places where there are people thanks to their adaptation to survive in diverse environments.