What animals or beings on Earth use water as their primary and ONLY source of energy/food ?

Answer 1

There is no organism on the surface of the planet, (NONE) that would use water as only, primary or secondary source of energy....
THey must have access to nitrogenated compounds such as nitrites, and ammonia,,They need to sinthesize proteins, structural or functional (enzymes) and that is impossible to achieve without a source of nitrogen..,the CO2 can be taken from the atmosphere, however, using ONLY water as source of energy, in itself, sounds absolutely impossible...
The aquatic plants may give you that impression, however, they thrive from nitrogen compounds syntezised in their floating roots, carried out by saprophytic bacteriae, that split nitrites, ammonia etc into simpler conmpounds that can be absorbed by he roots..
To prove this, jut try to grow, an acuatic plant in pure distilled water...It wont grow....or will die in 1-2days....
All living organisms, even monocellular either procariotic or eukariotic, need six molecule carbon compounds ( fructose or glucose phoshate) and phoshorous, to produce ATP in mitochondriae (if they are eukariotic) , or chloroplasts (if they are prokariotic)....
Water does not work as source of energy (unless we are talking here, about an atomic plant with all the uranium and deuterium water employed in the productionof heath) however the latter is not a living organism....

Answer 2

None.

There are plenty of animals which use their food as their primary source of water -- this is even possible without the food containing actual water. However this is an answer to a different question...

Andrew G -- your answer is to another question too. Insects and other organisms which survive on water alone are not using it for their energy, they are using their stored food for that.

Edit -

Sehr_Klug 50 -- good answer, but a couple of misunderstandings.

You are right that all organisms need a source of nitrogen -- however, this is not necessarily a source of energy -- for plants and other photosynthetic organisms it can be a non-food, inorganic nutrient. The energy source for water plants (as for all photosynthetic organisms) is of course light.

ATP is indeed produced in both mitochondria and chloroplasts. However, neither are found in prokaryotic cells, which by definition do not have organelles such as these. Only eukaryotes have organelles.

To be clear:

- Plants (and photosynthetic protists) have both mitochondria and chloroplasts. They produce ATP (therefore energy) in either, depending upon whether it is light, and on whether it is a green part of the plant. Plants in the dark, or plant parts such as roots or petals, don't photosynthesise, they just respire.

Animals, fungi, non-green plants and non-photosynthetic protists just have mitochondria, and so can only respire, not photosynthesise.

Prokaryotes also respire, and many (so-called blue-green algae) also photosynthesise. However, they do both (producing ATP) in the body of the cell, not in mitochondria or chloroplasts.

Even a nuclear-powered organism would not be using the deuterium in heavy water for energy -- as I recall, that's for damping the chain reaction. The energy comes from splitting unstable large atoms such as U235 or Plutonium.

Answer 3

Nothing can use water as a source of energy/food. All life needs water/fluids to prevent dehydration but besides that we all need some other form of nutrition (plants get it from the sun, animals get it from either eating plants or other animals).

Answer 4

Some animals can survive on water only, for instance some mature insects. Their bodies contain sufficient reserves of food for them to continue living; but when those reserves are used up they die. In these cases, the sole purpose of the adult stage is to procreate, and they do not need a source of energy to continue growing. They might need ater though, to help convert the food reserves to energy.
Many animals can survive on water only; provided they have sufficient energy reserves (eg, in a camel's hump). But without food, they too would eventually die.
People, too can survive for a surprisingly long period without food; living off their body fat. But without water, a person would die after a few days.

Answer 5

None at all. Even bacteria and viruses have other sources of energy: sugars or chemicals dissolved in water.

The sun is the primary source of energy for most ecosystems.

Answer 6

Water is a molecule composed of oxygen and hydrogen. These two compounds alone cannot combine into sugars or proteins therefore cannot support life by themselves. Water provides electrons for plants and in all life is the medium in which biochemistry occurs.

Answer 7

No animal can survive only on water. The water may contain other nutrients and thus help. Pure water cannot sustain life without other food.

Answer 8

none. water isnt an energy source for any specie because water itself, has absolutely no nutritional value. its only used to help other processes in the body.

Answer 9

nothing. water only contains hydrogen and oxygen. no one can live with only that. there should at least be some added carbon source from which energy can be derived.

Answer 10

water does not provide:

1. carbon content
2. mineral content

necessary for synthesis of any organic molecule required for living.