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Fish gills are organs that allow fish to breathe underwater. Most fish exchange gases like oxygen and carbon dioxide using gills that are protected under gill covers (operculum) on both sides of the pharynx (throat). Gills are tissues that are like short threads, protein structures called filaments. These filaments have many functions including ...
The body of a fish is denser than water, so fish must compensate for the difference or they will sink. Many bony fishes have an internal organ called a swim bladder, or gas bladder, that adjusts their buoyancy through manipulation of gases. In this way, fish can stay at the current water depth, or ascend or descend without having to waste ...
The density of the water prevents the gills from collapsing and lying on top of each other; [such collapse] happens when a fish is taken out of water." [ 4 ] Usually water is moved across the gills in one direction by the current, by the motion of the animal through the water, by the beating of cilia or other appendages, or by means of a ...
In fish, the long bony cover for the gill (the operculum) can be used for pushing water. Some fish pump water using the operculum. Without an operculum, other methods, such as ram ventilation, are required. Some species of sharks use this system. When they swim, water flows into the mouth and across the gills.
Other polymers, such as polyethylene and polystyrene, do not normally absorb much moisture, but are able to carry significant moisture on their surface when exposed to liquid water. [33] Type-6 nylon (a polyamide) can absorb up to 9.5% of its weight in moisture. [34]
Nearly all seafood, including fish and shellfish, contains trace amounts of mercury from the surrounding water, which they absorb when they feed, per the U.S. Food and Drug Administration.
The anatomy of fish is often shaped by the physical characteristics of water, the medium in which fish live. Water is much denser than fish, holds a relatively small amount of dissolved oxygen, and absorbs more light than air does. The body of a fish is divided into a head, trunk and tail, although the divisions between the three are not always ...
Evidence that fish are being contaminated by pharmaceuticals introduced into wastewater keeps building. That's clear as scientists look beyond drug levels in bodies of water and directly measure ...