Atriopore

Atriopore is a biological term referring to an external opening of the atrium, a body cavity associated with the pharyngeal region in certain invertebrate and chordate groups. The atriopore functions as a conduit between the atrial cavity and the outside environment, playing a role in the animal’s water flow dynamics, respiration, and feeding processes.

In tunicates (urochordates), the atrium surrounds the pharynx and its slits; water that has passed through the pharyngeal basket collects in the atrium and exits to the exterior through the atriopore, a feature that can be involved in the arrangement of the atrial region and the pathways of water flow. In cephalochordates such as amphioxus, the atrium similarly communicates with the exterior via an atriopore or atrial opening, allowing water to leave after circulating through the pharyngeal region.

Morphology and variation: The number, size, and position of atriopores vary among species and may serve as taxonomic characters in some groups. Some descriptions cite a single atriopore, while others describe multiple small pores along the atrial wall.

Function and significance: The atriopore contributes to maintaining the directional flow of water through the pharyngeal apparatus, supporting feeding and respiration, and aiding in the removal of wastes from the atrial cavity.

Etymology and terminology: The term combines “atrium” and “pore.” Some authors distinguish the atriopore from related terms such as the atrial siphon, depending on the particular anatomy described in a given group.