What's an animal?

Answer 1

This is absolutely not a dumb question - and in fact it is one that a number of scientists have spent years working on. We all know an animal when we see it running across a field or crawling on a leaf but when we get down to microscopic single-celled organisms it is sometimes very hard to distinguish plants from animals, which have many characteristics in common when you get down to that level. It seems that a clear distinction between animals and other groups of living things will have to be made at a genetic or biochemical level.

Believe it or not, the currently accepted scientific definition is basically "a living thing which is not a plant or fungus", or words to that effect. This is generally considered to be a very poor definition but no-one has yet to come up with a better one!

Attempts to define animals as "living creatures that cannot obtain energy by photosynthesis" collapse because fungi would be counted as animals; or "living creatures with the ability to move from place to place under their own power" collapse because plants like ferns have a sperm-like swimming "seed" to aid in their reproduction. Plants like the Venus Fly Trap and Mimulus have responsive sense organs and move so this cannot be used as part of a definition to distinguish plants and animals. Animals such as barnacles do not move so this excludes the ability to move as part of any definition. In fact all other attempted definitions have so far thrown up "exceptions to the rule".

The recent discovery of a particular type of gene which only seems to occur in animals has raised the possibility of a more acceptable and accurate definition which may be confirmed in the next few years. So far all animals whose DNA has been analysed have been found to contain at least one gene known as a HOX gene and this may well be used to define an animal in the future. During the process of evolution, it may well have been the case that one mutation of DNA to produce the first HOX gene was what created a living thing which was the ancestor of ALL animals from amoeba to elephant, tyranosaurus to human.

So all those people who have answered your question by saying that you're dumb and stating that the answer should be obvious are the dumb ones - your question is one of the most basic, fundamental and important questions in biology and the answer is by no means as obvious as most people think.

Answer 2

animal




an·i·mal [ ánnəm'l ]


noun (plural an·i·mals)

Definition:

1. living organism with independent movement: a living organism that is distinguished from plants by independent movement and responsive sense organs


2. mammal: a land mammal other than a human being

I got his definition off of MSN Encarta Premium Dictionary (& Thesaurus).

Instead of being a total jerk and just taking 2 points from you, I decided to actually ANSWER this girl/guy's question. (I assume your a girl.) Why do people have to be so inhumane sometimes? I wonder...

Answer 3

How could you ask that? I mean, an animal is an animal, not anything else!

Answer 4

Amphibian, reptile, herbivore, carnivore, insectovore, cnidarians, marsupial, introskeletals, extroskeletals, fish, sloth, human. Insect, arachnids, centipede, millipede, caterpillar, worm, butterfly, slug, snail, moth, ant, termite, moocow, chicken and other fowl. Why, did you want a specific answer?

Answer 5

i'm an animal, baby

Answer 6

Well that was dumb, if you don't know what an animal is you are deffinately in trouble, that's like asking what are you.

Answer 7

a living being

Answer 8

What? Need more details

Answer 9

a living creature...not a plant or human though.

Answer 10

what kind of question is that?Wait I know the answer! A dumb question!