what is the Smallest animal in the world?

Answer 1

Your question has a number of difficult aspects to it, but I have asked a friend of mine to help me do some research into the answer for you and I think he has included a great number of pieces of information that you may find interesting.
Here is what I eventually decided was the most productive answer to give you. I hope it helps you out! (after all, it is 99% his answer I have included below. He generally gives me such good feedback that I try to quote him directly as much as possible.)
Here we go: An animal is:
An organized living being endowed with sensation and the power of voluntary motion, and also characterized by taking its food into an internal cavity or stomach for digestion; by giving carbonic acid to the air and taking oxygen in the process of respiration; and by increasing in motive power or active aggressive force with progress to maturity.
OR:
Any of a kingdom (Animalia) of living things including many-celled organisms and often many of the single-celled ones (as protozoans) that typically differ from plants in having cells without cellulose walls, in lacking chlorophyll and the capacity for photosynthesis, in requiring more complex food materials (as proteins), in being organized to a greater degree of complexity, and in having the capacity for spontaneous movement and rapid motor responses to stimulation" These are the animal subkingdoms, and the principal classes under them:
* Vertebrata, including Mammalia or Mammals, Aves or Birds, Reptilia, Amphibia, Pisces or Fishes, Marsipobranchiata (Craniota); and Leptocardia (Acrania).
* Tunicata, including the Thaliacea, and Ascidioidea or Ascidians.
* Articulata or Annulosa, including Insecta, Myriapoda, Malacapoda, Arachnida, Pycnogonida, Merostomata, Crustacea (Arthropoda); and Annelida, Gehyrea (Anarthropoda).
* Helminthes or Vermes, including Rotifera, Ch�tognatha, Nematoidea, Acanthocephala, Nemertina, Turbellaria, Trematoda, Cestoidea, Mesozea.
* Molluscoidea, including Brachiopoda and Bryozoa.
* Mollusca, including Cephalopoda, Gastropoda, Pteropoda, Scaphopoda, Lamellibranchiata or Acephala.
* Echinodermata, including Holothurioidea, Echinoidea, Asterioidea, Ophiuroidea, and Crinoidea.
* Coelenterata, including Anthozoa or Polyps, Ctenophora, and Hydrozoa or Acalephs.
* Spongiozoa or Porifera, including the sponges.
* Protozoa, including Infusoria and Rhizopoda.

Answer 2

for a "real" animal I guess you couldn't go smaller than a unicellular. Bacteria range in size from 0.5 micron to 5 microns, though the smallest are just 0.2 micron.

viruses would of course be smaller, typically ranging in size from 10 to 300 nanometers (0.01 to 0.3 microns). But they're not really considered animals, being not much more than genetic material protected by a shell.

hope this helps

Answer 3

Since you're asking about animals, that rules out bacteria and protists.
There are several wormlike animals that'd probably fit the bill, then. I'm going to choose rotifers. The ones I've seen were about 100 micrometers, which is about the same size as the bigger protists.
Look up rotifers.

Answer 4

The smallest mammal would likely be the pygmy shrew. The smallest animal, would be some kind of insect, like a louse that lives on other insects.

Answer 5

The smallest animal is a species of shrew, which is related to mice.

Answer 6

I am not sure,but the South East Asia Philippine Tarsier is the most smallest monkey................maybe

Answer 7

yet to be born

Answer 8

Hai,
Ant(Not sure)