Editing Gastrulation (section)

==Protostomes versus deuterostomes==
[[File:Protovsdeuterostomes.svg|thumb|upright=1.2]]
The [[Embryological origins of the mouth and anus|distinction between]] [[protostome]]s and [[deuterostome]]s is based on the direction in which the mouth (stoma) develops in relation to the '''blastopore'''. Protostome derives from the Greek word protostoma meaning "first mouth" (πρῶτος + στόμα) whereas Deuterostome's etymology is "second mouth" from the words second and mouth (δεύτερος + στόμα).{{cn|date=April 2022}}

The major distinctions between deuterostomes and protostomes are found in [[embryonic development]]:
* Mouth/anus
** In [[protostome]] development, the first opening in development, the blastopore, becomes the animal's [[mouth]].
** In [[deuterostome]] development, the blastopore becomes the animal's [[anus]].
* [[Cleavage (embryo)|Cleavage]]
** [[Protostome]]s have what is known as ''[[Cleavage (embryo)|spiral cleavage]]'' which is ''determinate'', meaning that the fate of the cells is determined as they are formed.
** [[Deuterostome]]s have what is known as ''[[Cleavage (embryo)|radial cleavage]]'' that is ''indeterminate''.