42 votes
Accepted

Why do diseases in the tap water of developing countries affect people from developed countries more?

You can expect that someone drinking from a water source regularly will develop immunity to the pathogens in that water source by being repeatedly exposed to them. However, it's not quite right to say ...
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18 votes
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Does human organism consume water or is it only used as solvent?

Humans and all other animals actually are net producers of water ("metabolic water") by oxidizing sources of energy including fats, proteins, and carbohydrates - effectively the opposite of the ...
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  • 36.6k
9 votes
Accepted

What are these tiny creatures swimming around my aquarium?

Hard to tell because of the poor picture/video quality, but almost immediately the body shape, distinct "face", size and behavior made me think of a small invertebrate animal called a ...
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6 votes
Accepted

What terrestrial trait makes cetaceans so successful in an aquatic lifestyle?

Thermoregulation and echolocation both depend on evolutions that occurred on land and seem to be less accessible to fish than to the ancestors of mammals. The heat capacity of water is much greater ...
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  • 3,260
6 votes
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Do electric eels produce current as they just move about, and how/why?

You are right - the 800 Watts are not constantly produced: There are three types of electrical discharge: (i) low voltage (ii) high voltage doublets or triplets and (iii) high voltage high frequency. (...
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  • 666
6 votes
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What is a false crocodile?

If you keep reading the next sentence it makes clear what is meant (emphasis mine): Crocodiles (subfamily Crocodylinae) or true crocodiles are large semiaquatic reptiles that live throughout the ...
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6 votes
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Nutrient limitation in terrestrial and freshwater ecosystems

The traditional explanation for this is that nitrogen compounds are more mobile than phosphorus compounds. As a result, nitrogen is more likely to flow through terrestrial ecosystems and accumulate in ...
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  • 166
5 votes
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What is this plant/creature in my freshwater aquarium?

That is a hydra. They are a kind of jellyfish, and as such they do technically have stinging tentacles. However, they're also very small, so they're not a danger to most fish or shrimp. If you're ...
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  • 3,988
4 votes
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Which animal dug this 5 cm diameter hole deep into mud and build a large mound around it?

A crustacean (land crayfish). There are a lot to choose from. http://web.nchu.edu.tw/~htshih/crab_fw/fw-crabe.htm
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4 votes
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What kind of fish is this? Spotted or largemouth?

This looks like a spotted bass (Micropterus punctulatus). Here's an image showing some quick differences between some common bass species: Using the above photo and this source to guide our judgment ...
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4 votes
Accepted

Where does the mass come from when you grow plants in water?

Short answer Plants with storage compartments can grow for extended periods on water alone. Background It indeed seems the question is indeed different from the suspected dupe after all. According ...
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3 votes

How many Watt-hours can an electric eel produce in a day?

This research states that an eel whose size is 90 cm can provide 6.05 mW, which is 145 mWh every day. They say you'd need 165 eels to be able to read for 24 hours using a 1W lightbulb like the one on ...
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3 votes
Accepted

Are there any natural forms of aquatic vegetation which do not stand up in water?

Yes there are many aquatic plant species which do not stand up in water. You need to look at the lifeform of the plants, such as introduced by Raunkiaer ( https://en.wikipedia.org/wiki/Raunki%C3%...
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  • 358
3 votes
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The effect of depth on net primary production in aquatic ecosystems

After a quick glance at the book "Light and Photosynthesis in Aquatic Ecosystems" by Kirk (2010), I think that the cause for the productivity dip towards the surface partially lies in photoinhibition, ...
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2 votes

How does eutrophication yield lower levels of dissolved oxygen?

From Wikipedia: Eutrophication arises from the oversupply of nutrients, which leads to over growth of plants and algae. After such organisms die, the bacterial degradation of their biomass consumes ...
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2 votes

Do unique communities of bacteria form inside water storage in plants?

As stated in Plant Signal Behav. 2010 Dec; 5(12): 1568–1570: Phytopathogenic bacteria do not enter plant host cells, but proliferate in the intracellular space. But as they can reach the apoplast,...
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  • 121
2 votes

Land Shrimp Sighting (Western Europe): What is it?

The size (~2 inches), broad "quadrate" head, and long posterior abdomen leads me to believe this is a relative large larva of a Predaceous Diving Beetle (family Dytiscidae). The larvae are ...
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2 votes

Can someone identify this creature?

This is a Burrowing Mayfly nymph (order Ephemeroptera), more than likely of the family Ephemeridae. The Bugguide site has very few photos of nymphs, but you'll find a near miss here (the species ...
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2 votes

Are there adaptations in tropical fish to compensate for less oxygen in water?

Many can breath air directly ; examples - bettas, gouramis, paradise , some catfish . No doubt others that do not come to mind .
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2 votes
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Are there adaptations in tropical fish to compensate for less oxygen in water?

Fish that live in cold water for most of the year actually have particularly strong hypoxia-tolerance adaptations, i.e. from summer heatwaves and algal blooms, compared to fish that are better ...
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2 votes

What terrestrial trait makes cetaceans so successful in an aquatic lifestyle?

Advantages of air breathing over gills? Keeping in mind water-breathing animals could still evolve lungs. Not being vulnerable to parasites and diseases of the gills, which are obliged to have blood ...
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1 vote
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Fresh Water Fish Identification

Could well be the Rosy Barb, which is a common beginner fish (I believe, not being an owner of a tank at all). They have a distinctive reddish colouration which is brightest when in the mating season, ...
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  • 7,773
1 vote

How can animals that rely on SONAR not see color?

Color is a characteristic of visible electromagnetic spectrum, see the graph here. Electromagnetic means here that it has the same nature as radio-waves, X-rays, and gamma radiation, whereas visible ...
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  • 3,772
1 vote
Accepted

How many Watt-hours can an electric eel produce in a day?

I found some information on how much energy an electric eel can theoretically produce for an hour, but not per day. Thanks to this excellent answer from dtrades and my own research. Apparently, ...
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  • 273
1 vote

Did humans evolve the ability to swim? Or is it just luck that we are able to swim?

The Jane Goodall website says: "You’ll rarely see a chimp paddling about in the water as they don’t like to swim. Their low body fat ratio causes them to sink and their top heavy body composition ...
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1 vote

Is this aquatic plant duckweed or something else?

That looks very much like a duckweed. The multiple roots rule out most genera within this group and so this is probably a Spirodela. The apparently relatively large size and red undersides are ...
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  • 5,302
1 vote

I want to know the name of this water plant?

This is a water-primrose Ludwigia, probably Ludwigia peploides but I am not sure about the species (also because you didn't provide a location). Luwigia peploides and L. grandiflora are native to ...
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  • 3,647
1 vote

Can an Ichthyologist identify this Canadian freshwater fish?

Judging from the curved caudal (tail) fin, which is more square in brown trout, this appears to be a chinook salmon. The mouth also appears to be black whereas in brown trout the mouth is white. ...
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  • 1,007
1 vote

The effect of depth on net primary production in aquatic ecosystems

I think it has to do with what wavelength of light is absorbed by photosynthetic organisms at what depth. Ultraviolet light with short wavelength is absorbed closest to the surface. Red light (which ...
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1 vote

How does eutrophication yield lower levels of dissolved oxygen?

The oxygen is used up by bacterial decay of the plants and algae that overgrow when there is too much phosphorus or nitrogen available; the plants grow so quickly that they compete with each other for ...
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