View previous topic | View next topic

Eels

Page 3 of 4
Goto page Previous  1, 2, 3, 4  Next

Flash
161039.  Thu Mar 29, 2007 5:21 am Reply with quote

Ooops.

 
Gray
161046.  Thu Mar 29, 2007 5:30 am Reply with quote

From eggshaped's link:
Quote:
Before this, coordinated hunting was only seen in mammals and birds. In addition, until now the only other examples of cooperative hunting between species were seen with humans and dogs or humans and dolphins, Bshary said.


Hmm. Honeyguide birds, honey badgers and humans; cheetahs and humans; falcons and humans, dolphins, sharks and skewers/gannets/petrels; dolphins and tuna/jack; badgers and coyotes, fish and sea-snakes...

'Cooperation' is used a bit vaguely here - you could say that any animals near any other animal that is benefitting is 'cooperating'. The fact that they can see each other, and act accordingly, means that they are cooperating.

And also, all the different species of colonial animals that make up siphonophores (types of jellyfish) and all the other endosymbiotic cellular creatures (ourselves included), all of whose different cell species 'hunt' together.

The eukaryotic cell itself is an example of several different types of non-nucleated bacteria 'hunting' together, and eventually becoming symbiotic and forming the modern cell. Animal cells have mitochondria, which were separate species of bacteria, with their own DNA. Plants have chloroplasts - ditto.

 
dr.bob
161051.  Thu Mar 29, 2007 5:39 am Reply with quote

Quote:
Before this, coordinated hunting was only seen in mammals and birds. In addition, until now the only other examples of cooperative hunting between species were seen with humans and dogs or humans and dolphins, Bshary said.


What about humans and cormorants?

 
Flash
161063.  Thu Mar 29, 2007 6:05 am Reply with quote

I've witnessed whales herding small fish which then leap out of the water in an attempt to escape and get grabbed in mid-air by gulls.

 
MatC
161069.  Thu Mar 29, 2007 6:21 am Reply with quote

Farmed eels retain the instinct to “return” to the Sargasso Sea, no matter where they are born and raised.
- Western Daily Press, 24 March 07

 
dr.bob
161141.  Thu Mar 29, 2007 8:46 am Reply with quote

Flash wrote:
I've witnessed whales herding small fish which then leap out of the water in an attempt to escape and get grabbed in mid-air by gulls.


That's not really co-operation, though, is it? Like Gray was pointing out, that's just one animal exhibiting feeding behaviour for its own benefit, and another animal sneaking in and taking advantage.

A bit like seagulls hanging 'round a trawler.

Ooer! I seem to have turned into Eric Cantona.

 
Flash
161143.  Thu Mar 29, 2007 8:48 am Reply with quote

True, true.

 
Gray
161297.  Thu Mar 29, 2007 1:25 pm Reply with quote

The thing is, the whales will have adapted their behaviour to take advantage of the fact that the fish don't want to get too close to the surface (for fear of being speared by the birds), so they're actually benefitting from each other in the long term.

It's cooperation - it just doesn't appear that way because we like to think of the animals being 'mindful' (whatever that is) of the cooperation. It still happens, though. I expect the whales, in their whaley way, might be thinking "Ah yes, those birds are here now, we can go a little higher and really trap them."

This is all the purest, hard-nosed science, you understand.

 
dr.bob
161477.  Fri Mar 30, 2007 5:35 am Reply with quote

Surely fish tend to get trapped near the surface of the water since most of them have yet to figure out how to swim through the air. I'd imagine whales would take advantage of this fact whether the birds were there or not.

 
Gray
161567.  Fri Mar 30, 2007 9:41 am Reply with quote

Well quite, but you can see how it might apply in other species - that was just a bad example I chose. Still, 'cooperation' is a quite subjective term. It helps to think about the directions that information is travelling, especially in terms of the visual cues that each animal takes from the other.

The honey-guide/honey-badger one is better, because the outcome is obvious, and virtually impossible for either one alone. And the fact that the bird then goes and does the same trick on humans is unnerving. Birds - a lot smarter than we thought.

 
Molly Cule
163180.  Thu Apr 05, 2007 6:27 am Reply with quote

In the Fens people used to tie eels skin around their legs. Both men and women made garters from eels. They dried strips of eel skin in the sunshine and greased it with fat, then put the skin in a bag filled with thyme, marsh mint and lavender and buried for the whole of the summer. When the skin was dug out it was re-greased, polished and then tied around legs to ward off the fen ague which was common in those damp parts of the world.
S http://links.jstor.org/sici?sici=0015-587X(195806)69%3A2%3C112%3ASFBOTF%3E2.0.CO%3B2-3
The Book of Eels, Tom Fort

 
Molly Cule
163181.  Thu Apr 05, 2007 6:28 am Reply with quote

Eel skin used to be used to make door hinges. It was also used as a sieve for filtering things out of liquids.

According to Alexandre Dumas’s ‘Le Grand Dictionnaire de Cuisine’ the Egyptians ‘placed eels on a par with the gods…. They raised them in aquariums, whose priests were charged with feeding them with cheese and entrails.’
The Book of Eels

 
Molly Cule
163270.  Thu Apr 05, 2007 8:27 am Reply with quote

Sigmund Freud was interested in eel’s sexual organs. He worked in Trieste looking cutting up hundreds of eels to find out how their systems worked. He published a thesis called ‘observations of the form and fine structure of the looped organs of the eels considered as testes’ in which he wrote about how he thought he might have found the an immature testicle when looking at all these eels. He concluded that all of his research was a waste of time as he was no nearer to understanding the eels bits than when he first started.

The Book of Eels, Tom Fort p 80

 
Molly Cule
163272.  Thu Apr 05, 2007 8:32 am Reply with quote

As Autumn approaches and eels prepare to swim back to the Sargasso Sea of their birth, throughout the waters of the world they change physiologically; their backs turn darker, almost black, their bellies turn silver. They toughen up, storing fat in their muscle. Their eyes expand. Their nostrils dilate. They stop eating and their digestive tracts degenerate. The salt content in their bodies goes down. Their sex organs swell up. Then on a dark and stormy night when the waning moon is in it's last quarter the eels begin their exodus.

The book of eels p 136

 
Molly Cule
163273.  Thu Apr 05, 2007 8:34 am Reply with quote

Eels are able to live in salty and fresh water and to survive out of water for some time. Their skin can absorb up to 90% of its oxygen requirement. Their skin is so thick and covered in mucus so it stops osmosis from happening in salty water - other fish like salmon, trout, shad.. can't go in salty water as the salinity invades their bodies and kills them. An eel is perfectly happy in salt and fresh water alike.

 

Page 3 of 4
Goto page Previous  1, 2, 3, 4  Next

All times are GMT - 5 Hours


Display posts from previous:   

Search Search Forums

Powered by phpBB © 2001, 2002 phpBB Group