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Dolphins

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Flash
51120.  Tue Feb 14, 2006 9:54 am Reply with quote

Q: What do dolphins drink?
F: Water
A: They don't drink at all.

As they live in seawater dolphins live as desert animals, without any access to fresh water at all. They obtain fluids from their food (fish, squid, etc) and by metabolizing (burning) fat (which releases water).

Dolphins half-sleep by shutting down one half of their brain and the opposite eye. The other side stays awake and watches out for predators and obstacles, and remembers to go to the surface to breathe. Two hours later, the sides flip. (need to check what other animals do this).

The Chinese White Dolphin is pink (and extinct, according to Gray), as is the Amazon River Dolphin.

Killer Whales (orcas) are actually dolphins. (or not - at a minimum we need to clarify what we mean by this)

After Hurricane Katrina the Observer carried a story that 36 US Navy-trained attack dolphins had escaped and were roaming the sea armed with toxic dart guns. The story seems to have been a hoax; apart from anything else, dolphins aren't trained for attack, only for finding things.

Fish which live in salt water constantly lose fluids through osmosis, so they have to drink (their gills get rid of the salt and minerals), but freshwater fish do not have this problem, so don't drink at all (though they do absorb water through skin & gills). Some fish do both: salmon drink saltwater but when they enter freshwater streams to spawn, they stop drinking and instead absorb water through osmosis. So someone who 'drinks like a fish' is very abstemious.

Pictures/clips: dolphins swimming/leaping, pink dolphins, mock-up of dolphin with a dart gun?

Links to: other animals/people with unusual drinking habits (gemsbok, bushmen - both possibly linked to deserts).

 
Flash
51125.  Tue Feb 14, 2006 10:03 am Reply with quote

http://www.zoophile.net/dolphin.php answers all your questions about inter-species sex with dolphins, including "How do I know if a dolphin wants to have sex?" "What do I do if a dolphin wants to mate with me?" and "Where can I find a dolphin to mate with?"

 
Flash
51126.  Tue Feb 14, 2006 10:04 am Reply with quote

BTW, this question was originally one of Dan's.

 
Gray
51285.  Tue Feb 14, 2006 2:44 pm Reply with quote

Dolphins have nipples, of course, being mammals.

They each have a unique 'signal whistle' which seems to count as their name, but unlike our names, they are the only ones that use it - other individuals do not. They repeat it while in their groups, apparently as a message to let all the others know they are there without having to look for them.

There's a similar thing going on in China using bicycle bells. In the West, we use the bell to signal to someone to move it. In China, however, because there are so many cyclists, everyone rings their bells constantly. This gives each rider a 'sonar picture' of all the other riders around them so that they don't have to turn their heads to know who's near.

Males dolphins copy their mother's signal whistle very closely, possibly to avoid incest later on.

 
Flash
51299.  Tue Feb 14, 2006 3:10 pm Reply with quote

Quote:
There are nine million bicycles in Beijing, that's a fact, that's a thing you can't deny

... except, isn't that untrue nowadays? Maybe a Gen Ig thread here, but haven't bicycles actually been banned in some Chinese cities because they get in the way of the cars?

 
brackett
51314.  Tue Feb 14, 2006 3:34 pm Reply with quote

Actually my question was:

QUESTION

What do dolphins do once every two hours?

ANSWER


Shed their skin (Their entire body of skin, I believe, if that doesn't sound too crazy) This was discovered by Japanese scientists and it explains why dolphins glide through the water so well.

I'll have to find my original source for this, and get back to you - It came from New Scientist.

I think I put the dolphin half sleep in the Stephen notes to this question- I can't remember if it made it on the DVD though.

 
Flash
51316.  Tue Feb 14, 2006 3:42 pm Reply with quote

Ref the bikes in China, I think we're onto something, but I'll nip over to the GI forum to post it.

Tring tring!

 
MatC
58091.  Wed Mar 08, 2006 12:00 pm Reply with quote

Newborn dolphins and killer whales don’t sleep at all for a month after birth. Not a single wink.

Source: www.planetark.com/dailynewsstory.cfm/newsid/31478/story.htm

 
Gray
58108.  Wed Mar 08, 2006 12:35 pm Reply with quote

According to the IUCN:
Quote:
On the basis of surveys conducted in 1985 and 1986, Chen and Hua (1989) estimated that the total population was around 300 individuals. Numbers are thought to be much lower today. An intensive survey in November 1997 produced a total count of only 13 dolphins (Wang 2000). There may be no more than a few tens of Yangtze dolphins in existence today.

So they may be extinct, and according to Mark Carwardine's lecture that I attended last year, they probably are.

 
MatC
58944.  Sat Mar 11, 2006 10:30 am Reply with quote

“A naturally-occurring neurotoxin called domoic acid has been responsible for the deaths of hundreds of sea lions in southern California during the last few years. Domoic acid is a chemical that is produced by algae or plankton when it blooms. Domoic acid was not discovered until the late 1980s, and scientists still don't understand why or when the algae blooms occur, nor can they predict which blooms will produce toxins and when they will impact wildlife. What is known is that anchovies, sardines, clams, mussels and other sea life ingest the algae. Then when sea lions (and to a lesser extent, dolphins) eat the anchovies and other affected sea life, they become sick.
The toxin affects the part of the brain known as the hippocampus and causes rapid deterioration. Affected sea lions exhibit head weaving, bobbing, bulging from the eyes, mucus from the mouth, disorientation and sometimes seizures.”

- www.surfrider.org/a-z/domoic_acid.asp

 
MatC
60415.  Fri Mar 17, 2006 7:47 am Reply with quote

Skate - the fish - “possesses an almost exact replica of the human penis and testicles. In Normandy the fishmongers coyly place a little frilled paper cap over the offending genitals.”

I don’t have much confidence in the source here (‘The Compendium of Nosh’ by Jack McLean [John Murray 2006]), and have been unable to find anything elsewhere. Any offers?

(Sharks don’t have penises at all, though, according to http://oceanlink.island.net/ask/chondrichthyes.html)

 
Flash
63446.  Sun Apr 02, 2006 3:18 pm Reply with quote

For the dolphin notes, maybe:

Amongst the many curious stories relating to Scott's Antarctic expedition there's one about killer whales preying on their ponies. Apparently if the ponies were on an ice floe the orcas would throw themselves up onto the floe, causing it to tip. The ponies then slid into the water and got eaten. Presumably this is a strategy they use against seals, but they are known to have been quite inventive in other hunting methods. They drown juvenile Blue Whales by surrounding them and preventing them from surfacing, and an orca in Friendship Cove aquarium discovered that it could regurgitate fish onto the surface to attract sea gulls which it would then eat, and other orcas then learned the behaviour by example.

They are dolphins, as has been noted elsewhere on this board, but the distinction between 'whales' and 'dolphins' is not a scientific one so it isn't altogether clear to me what that means (the Delphinidae are members of the cetacean suborder Odontoceti, the toothed whales). There's a slightly bad-tempered discussion of the issue in the Wiki discussion page for the Orca article at: http://en.wikipedia.org/wiki/Talk:Orca/Is_it_a_dolphin%2C_a_whale%2C_both%3F%21

 
eggshaped
136380.  Fri Jan 19, 2007 9:49 am Reply with quote

Just for reference, I've found a link for Brackett's fact about dolphins shedding their skin.

http://physicsweb.org/articles/news/8/5/8/1

 
fishfool
371695.  Tue Jul 01, 2008 5:05 am Reply with quote

Dolphins are extremely and almost constantly vocal. They are capable of two kinds of sounds. A specialized mechanism in the nasal passages just below the blow-hole enables them to emit short, pulse-type sounds. These sounds, called clicks, can be produced in such rapid succession as to sound like a buzz or even a duck like quack. The clicks are used as a form of sonar, in which echoes of sounds from surrounding objects enable the animals to detect obstacles, other dolphins, fish, and even tiny bits of matter in the water. The military uses dolphins and this ability to help them find water minds. This ability is termed ECHOLOCATION. Some Scientists have speculated that dolphins also use the sounds to deliver an acoustic shock for stunning of killing small prey.- taken from the dolphinplace.com - -Fishfool

 

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