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gill

Primary Information
Secondary Information

Definition

A gill is a respiratory organ that allows fish and other aquatic animals to breathe underwater. Gills are made up of thin, feathery structures called lamellae. The lamellae are arranged in a series of folds, which increase the surface area of the gills. This allows more oxygen to diffuse into the bloodstream.

The gills are located on the sides of the fish's head. They are covered by a flap of skin called the operculum. The operculum helps to protect the gills and to keep water flowing over them.

When a fish breathes, it opens its mouth and takes in water. The water flows over the gills, and the oxygen diffuses into the bloodstream. The blood then carries the oxygen to the rest of the body.

The amount of oxygen that a fish can absorb through its gills depends on a number of factors, including the temperature of the water, the amount of dissolved oxygen in the water, and the activity level of the fish.

How can the word be used?

The gill slits on the fish's sides allowed it to breathe underwater.

gill

Different forms of the word

Noun: gill.

Adjective: gilled.

Verb: to gill.

Etymology

The word "gill" comes from the Old English word "gyl". The Old English word "gyl" comes from the Proto-Germanic word "gilja", which means "branch" or "twig".

Question

What are gills used for?

AQA Science Exam Question and Answer

Question: How do gills work?

Answer:

Gills are respiratory organs that allow fish and other aquatic organisms to extract oxygen from the water. Gills are made up of thin, feathery filaments that are highly vascularized. This means that they have a lot of blood vessels that carry oxygen to the cells of the organism.

When a fish swims, water flows over the gills. The water passes through the thin filaments, and the oxygen in the water diffuses into the blood vessels. The blood then carries the oxygen to the cells of the organism, where it is used for respiration.

Gills are very efficient at extracting oxygen from the water. A fish can extract up to 80% of the oxygen in the water that passes over its gills. This allows fish to live in water that is much lower in oxygen than air.

Here are some additional details about how gills work:

  • The thin, feathery filaments of the gills increase the surface area of the gills, which allows more oxygen to be extracted from the water.
  • The blood vessels in the gills are very close to the surface of the filaments, which allows the oxygen to diffuse quickly into the blood.
  • The beating of the fish's gills helps to create a current of water that flows over the gills, which helps to ensure that the gills are always supplied with fresh water.
  • Gills are very efficient at extracting oxygen from the water, but they can also be damaged by pollution. Pollution can reduce the amount of oxygen in the water, which can make it difficult for fish to breathe.