Entrance into the archenteron as found during early embryonic development.

In addition to the archenteron, the blastopore is the main end product of the process of gastrulation and is a dominant feature of gastrula.

As the archenteron is equivalent to a gut, the blastopore is equivalent to a primitive mouth and/or . See protostome versus deuterostome versus the concept of a gastrovascular cavity such as one sees with jellyfish.