Definition

Noun: 1. A respiratory organ found outside the body: An "external gill" is a gill that is not enclosed within a body cavity or chamber. It is exposed to the surrounding water or environment and is used for breathing. This structure is a defining feature of the larval stage (e.g., tadpoles) of many amphibians and occurs in some mollusks and other aquatic animals.

Examples of Usage

• Noun:
  • The tadpole uses its feathery external gills to extract oxygen from the water.
  • Unlike fish, which have internal gills protected by an operculum, the axolotl retains its external gills throughout its life.
  • The presence of external gills is a key characteristic of the larval stage in many salamander species.

Advanced Usage

• "Retain external gills": Used in biology to describe a condition where an animal keeps its juvenile gills into adulthood, a phenomenon known as neoteny.
  • The axolotl is famous for its ability to retain external gills as an adult.

Variants and Related Words

• Gill (n): The general respiratory organ of many aquatic organisms.
• Internal gill (n): A gill that is contained within a body cavity, such as the gills of a fish protected by an operculum.
• Branchia (n): The technical zoological term for a gill.

Synonyms

• Branchial plume (n): A descriptive synonym emphasizing the feathery, plume-like appearance of many external gills.

Related Terms (Contextual)

• Larva (n): The immature, juvenile form of an animal that undergoes metamorphosis, often possessing external gills.
• Neoteny (n): The retention of juvenile features in the adult animal.
• Respiration (n): The process of breathing.

Noun

1. occurs in some mollusks and in tadpoles and other immature amphibians