In life, a subphylum is a taxonomic rank intermediate between phylum and superclass. The rank of subdivision in plants and fungi is equivalent to subphylum.

Not all phyla are divided into subphyla. Those that are include:

* Arthropoda: divided into subphyla Trilobitomorpha, Chelicerata, Myriapoda, Hexapoda and Crustacea,
* Brachiopoda: divided into subphyla Linguliformea, Craniformea and Rhychonelliformea,
* Chordata: divided into Urochordata, Cephalochordata, and its largest subphylum Vertebrata.