Taxonomic Groups
Kingdom:
Many research organisms
are animals--they come from the Kingdom Animalia. Some researchers
use living things from the other kingdoms, Plantae, Fungi, Monera and
Protista.
Phylum
(plural- phyla):
There are several phyla
within each kingdom. Organisms are broken into smaller, more
recognizable groups based on their general body plan. Most
research animals belong to the phylum Chordata, animals that have a
dorsal central nervous system, a notochord during embryonic development
(a stiff cartilage structure under the dorsal surface of the body), and
gills or lungs. Most chordates have a spinal column (and are
called vertebrates). Mammals, birds, reptiles, amphibians, and fish belong
to the phylum Chordata. Other animal phyla include Arthropoda (insects and spiders), Mollusca (snails and clams), Annelida
(earthworms), and Echinodermata (starfish and sea urchins).
Class:
The next level of taxonomy is the class. Several classes are found in each
phylum. The classes of phylum Chordata are:
- Mammalia (mammals)
- Aves (birds)
- Reptilia (snakes, lizards and
turtles)
- Amphibia (frogs and salamanders)
- Osteichthyes (bony fish, such as
trout and goldfish)
- Chrondrichthyes (cartilaginous
fish, such as sharks and rays)
- Agnatha (jawless fish, such as
lampreys)
Mammals are the most
commonly used class of animals in research. They are vertebrates
that nourish their young with milk from the females' modified sweat
(mammary) glands and have skin that is (more or less) covered with
hair.
Order:
Several orders make up
each class. Some common orders of Mammalia used in research
include:
- Primates (monkeys, apes and
humans)
- Lagomorpha (rabbits and hares)
- Rodentia (mice, rats, hamsters
and guinea pigs)
- Carnivora (dogs, cats and
ferrets)
Family:
Several families make up
each order. Family names always end in -idae.
Families in the order Rodentia used for research include Muridae (rats
and mice), Cricetidae (hamsters and gerbils), Cavidae (guinea pigs) and
Chinchillidae (chinchillas).
Genus (plural- genera):
Each family contains from one to many
genera. Animals within the same genus are very closely related.
Genera within the family Muridae include Rattus (the
"Norway" rat) and Mus (the
"house" mouse).
Species:
A species is a group of animals that is reproductively isolated from all
other groups of animals; one species can't, in other words, breed
with another species. This is not an absolute, however, because
some similar species can interbreed (the horse and donkey, for
example, produce a mule when bred together). The species name of the
common laboratory rat is Rattus norvegicus (it can also be
written Rattus norvegicus).
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