Naked Science Forum
Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: CapnRedChops on 04/05/2009 13:26:08
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Hello all,
Having listened to several 'Question of the Week' podcasts I decided to bite the bullet, register on the forum and submit a question that has been on my mind for years...
You see, I have recurring dreams that back when rivers could be described as mighty, before we took much of their flow for human purposes, whales would swim up the largest of them (presumably to 'spawn'), and then return to the sea. In these dreams, I see whales gently breaching as they swim upstream in a river that is often 500 metres wide, sometimes wider. Obviously they would not go all the way to the source!
These dreams are unusually vivid, and have a captivating effect on me - I remember most of the details from these dreams, which are always different.
Is there any evidence that whales once swam up the larger rivers, perhaps prior to human history?
Could this possibly explain beaching - perhaps whales beach themselves based on a racial memory of a river mouth that was once located there, but has, in the twisting nature of rivers, moved away? Perhaps there is a similar river related theory that could explain beaching?
Is there any physiological reason that we can be certain of as to why the whales of the distant past could not do this?
On a tangent, I note with sadness that a species of river dolphin from China has just become extinct.
This is a tragedy.
On yet another tangent, Amazonian river dolphins (the best known river dolphins) are exquisite creatures, with much more flexible necks that marine dolphins - in my opinion, they look a lot more human as a result. They have existed in a mutualistic relationship with the native peoples, herding fish into the fisherman's net and receiving a cut of the catch in return.
I couldn't find the forum guidelines about embedding videos or posting links (yes, I looked), so I'll just advise you to search for river dolphins in youTube.
CRC
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You are not going to find an Amazonian river dolphin in China. The Amazonian River dolphin is on the endangered list.. the recently announced extinct dolphin is the Chinese river dolphin the Baiji . And it is a shame that in this day of knowledge in conservation that we still lose species.
As for the whale thing.. another theory is that the use of sonar by shipping industries is interfering with whales communication.
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Sorry, I should have separated the 2nd and 3rd last paragraphs: I did not mean to imply that the Amazonian River Dolphin is found in China, I just abruptly switched tangents.
CRC
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There are (or were) 3 species of freshwater dolphin. Amazon river dolphins, Yangtze river dolphins and Indian river dolphins. Also the Irrawaddy dolphin and Tucuxi dolphin, which are oceanic species, are known to enter fresh water at times, as is the Finless Porpoise. There are a number of Whales which venture into brackish and fresh water. Humpbacks, Grays and even the odd Orca have been seen in rivers such as the St. Lawrence, Sacramento, Thames & Clyde. But it is the White Whale of Moby Dick fame, the Beluga, which is the most commonly seen whale in fresh water. I believe that there was even a report of a Blue Whale being stranded in a river (Tasmania)in the early 19c!!! Personally I would imagine this to have been a case of taking a wrong turn, but who knows? However, to the best of my knowledge, no whale lives in freshwater permanently.
Oh! With one exception!!!
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fresearch.yale.edu%2Fpeabody%2FCICHLID%2FPP%2Fpolli.jpg&hash=fb9223b1088cb77260a4f45963f843cc)
Pollimyrus castelnaui Common names, Dwarf Stonebasher or Baby Whale, but it is a fish, not a whale.