Words of Wisdom:

"Just living is not enough... One must have sunshine, freedom, and a little flower. " - Kat197826

Animals

  1. An Argument For Animal Research
    part to conserve. It takes a lot of time, money, and care to take care of animals that are going to be subjects of tests. "No responsible scientist would incur the...
  2. Animal Rights
    paper will discuss the pros and cons of animal experimentation and research, animals in the classroom, animal organizations and hunting. Along with these topics my...
  3. Animals In The Research Lab
    new ideas. But, in the end, the results obtained must be verified in appropriate animal systems and, possibly as the final step, in clinical trials using humans who...
Date Submitted:
06/17/2010 07:47 AM
Flesch-Kincaid Score:
33 
Words:
2726
Essay Grade:
no grades
Flag
Join Now!

Already a Member? Login Now

Animals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also heterotrophs, meaning they must ingest other organisms for sustenance.

Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago.
Etymology
The word "animal" comes from the Latin word animal (meaning with soul, from anima, soul). In everyday colloquial usage, the word usually refers to non-human animals.[1] Frequently only closer relatives of humans such as vertebrates or mammals are meant in colloquial use.[2] The biological definition of the word refers to all members of the Kingdom Animalia, encompassing creatures ranging from insects to humans.[3]

Characteristics
Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and are multicellular[4] (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic,[5] generally digesting food in an internal chamber, which separates them from plants and algae.[6] They are also distinguished from plants, algae, and fungi by lacking rigid cell walls.[7] All animals are motile,[8] if only at certain life stages. In most animals, embryos pass through a blastula stage, which is a characteristic exclusive to animals.

Structure
With a few exceptions, most notably the sponges (Phylum Porifera) and Placozoa, animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissue, which sends and processes signals. There is also typically an internal digestive chamber, with one or two openings. Animals with this sort of organization are called...
Join Now to View the Full Essay

Comments

Express your owns thoughts and ideas on this essay by writing a grade and/or critique.

  1. No comments