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24

The answer to this, I reckon, is that they don't. They use molecular oxygen (O2) dissolved in the water for respiration, where it acts as a terminal electron acceptor, just as we use molecular oxygen in the air for respiration. We can speak of the water as being oxygenated. Water is split in photosynthesis, where reducing equivalents from water are used ...


10

Answer The mechanism for salmon natal homing isn't exactly known, but there are really two good hypotheses out there. Salmon have an extremely good sense of smell. One hypothesis is that they retain an imprint of their birthplace's odor, and manage to recognize it again at a later time (as explained by this article). Another hypothesis: the Earth's ...


5

Intelligence is something which has to have a definition, and there are many, but I would cautiously say no. The reason that I say this is because swarming behavior can be largely reproduced by a simple set of rules - matching distance to your neighbors and direction and speed as well. To me this really removes any intention or even conscious element to ...


4

The mechanisms of osmoregulation is different for sharks (and other elasmobranch fishes) and teleost fishes. In Elasmobranchs the body osmolarity is maintained equal to the seawater by Na⁺ Cl⁻ and urea. Toxicity because of high concentrations of urea (strong chaotrope) is counteracted by high levels of trimethylamine oxide (TMAO). So, the elasmobranchs do ...


4

I can't answer your third, but I can answer your first two. With one word, in fact: Bioluminescence http://brightnepenthe.blogspot.com/2010/08/palate-cleanser-90.html That's the deep ocean at night for ya. Unlike underground environments and caves, it's not pitch black pretty much anywhere in the ocean. There are things to see everywhere, and they play ...


3

It's probably bacteria. Here's a pdf describing the phenomenon, along with an in-depth history of the reported occurrence, which should tell you everything you might want to know. These seafood products exhibited luminescence due to the presence of certain bacteria that are capable of emitting light. Luminescence by bacteria is due to a chemical ...


2

To add some detail to Christian H's answer, while fish tend to move from side to side (lateral undulation), the land ancestors of marine mammals had their limbs under them and so their spines were adapted to up and down movement (dorsoventral undulation). Hence, vertical tails in the former and horizontal in the latter (the wikipedia article on fins gives ...


2

Wikipedia has some revealing information here: Not all puffers are necessarily poisonous; Takifugu oblongus, for example, is a fugu puffer that is not poisonous, and toxin level varies wildly even in fish that are. A puffer's neurotoxin is not necessarily as toxic to other animals as it is to humans, and puffers are eaten routinely by some species of ...


2

Indeed tuna are present in the Baltic sea, and they can also grow in the Pacific and Indian oceans. A lot of the tuna we see in tuna cans in supermarkets comes from the stocks in the Indian ocean, but it is possible to have fresh tuna from the Baltic. Sorry, I only found a French answer from a famous French news paper: ...


2

I only found this two references, but these are only secondary sources at the moment. Look here "Clown Fish Anemone" and here "Choosing Clownfish and Anemones for Your Aquarium". It seems that there are only around two handful of anemones capable of supporting clownfish. Here are some primary sources which confirm the 10 anemone species: "The anemonefish ...


1

When we talk about "artificial intelligence" we are talking about the ability to solve problems not directly specified in the code. It doesn't need to have "intention" or "conscience", as @shigeta suggests. So, I'd say swarms are intelligent, it's just another "hardware" where intelligence appears. Like shigeta said, our own mind is not different in essence ...


1

Sockeye salmon species definitely do, although admittedly the interesting salmon are those that spend significant time in the ocean. Here's some evidence that carp can. Raindbow trout are also capable. Zebrafish are also able. Japanese eels too, of which some are freshwater.


1

If by 'fishery' you mean "amount of fish caught", the answer is a qualified no. Sweden's catch has been stable or perhaps slightly increasing since a low in 2005, but the catch is still much lower than a decade ago (Statistics Sweden). This is presumably due in large part to the quotas set on Total Allowable Catch for various sea regions. If by 'fishery' ...



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