Search results
Results from the WOW.Com Content Network
A fish's hypoxia tolerance can be represented in different ways. A commonly used representation is the critical O 2 tension (P crit), which is the lowest water O 2 tension (P O 2) at which a fish can maintain a stable O 2 consumption rate (M O 2). [2]
The African lungfish is an example of how the evolutionary transition from breathing water to breathing air can occur. Lungfish are periodically exposed to water with low oxygen content or encounter situations in which their aquatic environment dries up.
Whether fish sleep or not is an open question, to the point of having inspired the title of several popular science books. [ 2 ] [ 3 ] In birds and mammals, sleep is defined by eye closure and the presence of typical patterns of electrical activity in the brain, including the neocortex , but fish lack eyelids and a neocortex.
Breathing air is primarily of use to fish that inhabit shallow, seasonally variable waters where the water's oxygen concentration may seasonally decline. Fish dependent solely on dissolved oxygen, such as perch and cichlids , quickly suffocate, while air-breathers survive for much longer, in some cases in water that is little more than wet mud.
In species like the spiny dogfish and other sharks and rays, a spiracle exists near the top of the head that pumps water into the gills when the animal is not in motion. [5] In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange. The muscles on the sides of the pharynx push the oxygen ...
The shared trait of breathing via gills in bony fish and cartilaginous fish is a famous example of symplesiomorphy. Bony fish are more closely related to terrestrial vertebrates, which evolved out of a clade of bony fishes that breathe through their skin or lungs, than they are to the sharks, rays, and the other cartilaginous fish. Their kind ...
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish (but not cartilaginous fish [1]) that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, which expends more energy. [2]
Because of their capability to use atmospheric oxygen, these fish generally are not so dependent on a form of aeration in their tanks, as they can rise to the surface of the water and take a breath, or breathing apparatus. Many of the labyrinth fish are peaceful and do well in most community tanks. However, individual males, especially the ...