Branchi

Branchi refers to the respiratory organs of many aquatic animals, primarily fish and some amphibians. These structures are adapted to extract dissolved oxygen from water and release carbon dioxide. In fish, branchi are typically located on either side of the head, often protected by an operculum. They consist of feathery filaments rich in blood vessels. Water flows over these filaments, allowing for efficient gas exchange. The high surface area of the branchial filaments maximizes the rate at which oxygen can diffuse into the bloodstream.

The structure and function of branchi vary among different species. For instance, the arrangement of gill rakers, bony or cartilaginous projections, helps filter food particles from the water as it passes over the branchi. In larval amphibians, branchi are external and may be lost or modified as the animal metamorphoses into a terrestrial or semi-aquatic adult. The term "branchial" is often used as an adjective to describe anything related to these respiratory organs, such as branchial arches or branchial circulation. The health of an animal's branchi is crucial for its survival, as damage or disease can impair its ability to breathe.