gilled

Gilled is an adjective meaning having gills, or relating to gills, the respiratory organs used by some aquatic organisms to extract oxygen from water. In zoology, gilled describes animals that possess these organs. Most fish have gills throughout life, while many amphibians display gills only during larval stages; some salamanders retain external gills into adulthood. Gills typically consist of filamentous tissue with numerous lamellae, increasing the surface area for gas exchange, and they are supplied by a dense network of blood vessels. Gas exchange often occurs by countercurrent flow, which maximizes oxygen uptake from water. Some taxa show variations such as external gills, as seen in axolotls, or internal gill slits that are lost during metamorphosis.

In mycology, gilled refers to mushrooms with gills (lamellae) on the underside of the cap. These gills bear the spore-producing cells and are a principal feature used to identify many species. Gilled mushrooms include numerous edible forms as well as several poisonous ones; their appearance is a key characteristic distinguishing them from poroid (pored) or non-gilled mushroom types.

The term can also appear in broader descriptive contexts, noting gill-like structures in other aquatic organisms. However, its primary senses relate to respiration in fish and certain amphibians, and to the lamellate undersides of many mushrooms.