What is phylum in environmental science?

What is the definition of a phylum?

I'm getting into the phylum thing and I'm not sure what the difference is between the phylum, class, order, family, genus, species, and so on.

Is it just a taxonomic classification or do they have something to do with evolution? I'm really confused by this. I'm going to need to find a decent definition of what each of these terms mean. I think I remember reading somewhere that the phylum is the grouping of a bunch of species that have a common ancestor and I think they evolve in the same way.

So I guess a phylum is a clade, but the clade of which class? The family? I think I read somewhere that all species of a phylum are related, but I can't remember where that was. If someone could give me a definition of what a phylum, class, family, genus, species, order, etc. Is and when they relate to one another I'd be very grateful.

2 Answers.
Phyla are defined based on their taxonomic rank. A phylum is an assembly of closely related taxa (eg genera) that share a common ancestor. A phylum can include orders, classes, families, and even genera (subgenus). So you can define a phylum as: a group of closely related taxa that share a common ancestor.

The phyla listed above are not necessarily related, except for Kingdom Protista, Fungi, and Plantae (the three kingdoms of living organisms). Jared L.SantosMar 18 '13 at 17:35 1

@JaredL.Santos, that is exactly what I wanted to hear. Thank you so much for that.

KevinMar 18 '13 at 17:46. 1

What about Archaea?SantosMar 18 '13 at 17:48. 1

This is a great question, and I'll try to answer it as thoroughly as I can. It's a bit long, so let me know if there are any questions.

What class is phylum?

It's the first level of taxonomy, the classification of organisms.

The phylum is defined as: a rank in the classification of animals or plants below that of a. Source: In other words, it is an artificial division into smaller groups based on some distinguishing feature (characteristic) or common origin. This distinction was introduced by Richard Owen in 1842 to separate and distinguish the two groups of animal phyla. He defined the term in his paper as:
In all the orders which I have called by this name, the organs of. reproduction, the generative system, the mode of locomotion, and the. shape of the mouth, are the same in the species of both sexes; but. besides these points of similarity, there is a general agreement as to. the construction of the shell, and the mode of mollusca and vertebrata. in the two classes.