Kingdom Animalia
Kingdom Bacteria
Kingdom Protozoa
Kingdom Plantae
Kingdom Fungi
Animals and plants are grouped into several categories which indicate their degree of relationship, one to another.
These, starting from the general to the specific, are:
All taxonomic categories above the species level are to some extent artificial and subjective - and when breeding habits are not known, this applies within the species category too.
Despite this, all categories should ideally reflect evolutionary relationships.
From specific to general:
Species to Orders
Species
The fundamental unit of taxonomy is the species. This is a group of very similar individuals that have the potential to interbreed freely, to produce fertile offspring - but cannot interbreed successfully with individuals from other species.Hence, the mule is a cross between 2 species (the horse and the donkey) but is infertile - as is the zho, a cross between the Himalayan yak and a domestic cow (and with its 'alt. sp.' of "zo", a very useful word in Scrabble© it is too!).
(There are, as ever, exceptions where the rule breaks down, especially in the plant Kingdom. However, in the majority of cases, interbreeding of species does not produce fertile offspring.)
In palaeontology however, it can never be known for certain whether a population with a particular morphology was reproductively isolated or not. Hence, the definition of a fossil species (and most living specimens) must be based almost entirely on morphological criteria. Sometimes, this can be supplemented by a comparison of the chemistry of the shell, but only rarely.
The scientific name for a species consists of 2 parts - it is binomial, with a generic name followed by a trivial (or specific) name.
It is always given in italics, and both names begin with a capital letter, such as Echinocorys Scutata
A species may sometimes be further divided into sub-species, in which case it will have three names. [the third being its WHAT is is called?]
Genus
The generic name refers to the genus, which is a group of species that are fairly closely related - such as the genus Equus which includes several species, such as the Equus caballus, Equus asinus and Equus zebra (domestic horse, wild ass and zebra respectively).The generic name (Equus) can be used alone, to describe a genus, whereas the specific name is always used with the generic name - it is meaningless when used alone.
The generic name always begins with a capital letter, and generic and species names are always printed in italic (or underlined when writing or typing, when italic is not available).
Family
Genera are grouped into families, which are major groups of generally similar organisms; such as Felidae, which includes all cat-like animals from domestic cat to wild lynx to tiger to cheetah to jaguar to snow leopard.Every continent (with the exception of Australia and Antarctica) has its own genus of cat, but all are of the Felidae family.
Family names always end in the letters "ae", but are not printed in any special way.
Order
Families are grouped into orders, whose individuals may vary in many ways; such as the order of Carnivora - which includes cats, dogs and weasels.However; all members vary significantly from the plant-eating animals, such as those in the major order Artiodactyla, which includes the pigs, deer, giraffe and antelopes.
Orders begin with a capital and usually end in "a" - but not always, so it is not always easy to tell what is an order!
Class to Kingdom
Orders are grouped into classes, classes into phyla and phyla into kingdoms.Class
The class is a major division within the animal Kingdom, and form the basis on which most fossil study is based.For example, the phylum Molluscas contains 4 classes: the Gastropoda, Cephalopoda, Pelecypoda and Scaphopoda, of which Gastropoda and Cephalopoda are common vocabulary within the geological, and palaeontological worlds.
Phylum
Classes are grouped into phyla (the plural of phylum), and phyla into Kingdoms.There are only about 30 phyla in the animal kingdom, and only about a dozen of these (including Mollusca and Brachiopoda) leave any fossil remains. Thus, the vast majority of life has left no evidence for us to find.
Within the animal Kingdom, Animalia, the most common phyla are:
- Arthropoda (e.g. insects)
- Mollusca (e.g. snails)
- Chordata (e.g. fishes, amphibians, reptiles, birds, mammals)
- Platyhelminthes (e.g. tapeworms)
- Nematoda (i.e. unsegmented worms)
- Annelida (i.e. segmented worms)
- Cnidaria and Ctenophora (e.g. jellyfish)
- Echinodermata (e.g. starfish)
- Porifera (e.g. sponges - * see below)
Kingdom
Various web resources list either 3, 4 or 5 Kingdoms of life, the most common being that of:| Monera | : prokaryotes (i.e., without a nucleus) |
| Protista | : single-celled eukaryotes |
| Fungi | : unique group of eukaryotes (based on nutrition) |
| Planta | : multicellular algae and plants |
| Animala | : multicellular animals |
