Fish physiology

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IX. Metabolism
Send this link to let others join your presentation: The red myotomal muscles derive their colour from myoglobin , an oxygen-binding molecule, which tuna express in quantities far higher than most other fish. In other projects Wikimedia Commons. The fish is now able to split ATP at a higher rate and ultimately can swim faster. In some cases, the openings may be fused together, effectively forming an operculum. Fish circulatory system In circulatory system:

The digestive system


The pancreas may be embedded in it, diffused through it, or broken into small parts spread along some of the intestine.

The junction between the stomach and the intestine is marked by a muscular valve. Pyloric ceca blind sacs occur in some fishes at this junction and have a digestive or absorptive function or both.

It is short in predacious forms, sometimes no longer than the body cavity, but long in herbivorous forms, being coiled and several times longer than the entire length of the fish in some species of South American catfishes. The intestine is primarily an organ for absorbing nutrients into the bloodstream. The larger its internal surface, the greater its absorptive efficiency , and a spiral valve is one method of increasing its absorption surface.

Sharks, rays, chimaeras , lungfishes , surviving chondrosteans , holosteans , and even a few of the more primitive teleosts have a spiral valve or at least traces of it in the intestine. Most modern teleosts have increased the area of the intestinal walls by having numerous folds and villi fingerlike projections somewhat like those in humans.

Undigested substances are passed to the exterior through the anus in most teleost fishes. In lungfishes, sharks, and rays, it is first passed through the cloaca, a common cavity receiving the intestinal opening and the ducts from the urogenital system. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Your contribution may be further edited by our staff, and its publication is subject to our final approval.

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The digestive system The digestive system , in a functional sense, starts at the mouth , with the teeth used to capture prey or collect plant foods. Previous page The skin. Page 6 of 9. Next page The respiratory system. Learn More in these related Britannica articles: Of the approximately species of freshwater fish of the United States, Canada, and Mexico, about 40 have become extinct in the past….

The earliest known vertebrates were jawless fishes of the class Agnatha, and their only living representatives are the cyclostomes—the lampreys and the hagfishes.

The modern agnathans retain much of the general organization of the ancestral vertebrates, and, therefore, much of their musculature is…. Similar to other vertebrates, fish have discrete taste and smell systems; however, since they live in water, the taste system is not confined to the oral cavity. For example, taste buds occur on the lips, the flanks, and the caudal tail fins of some….

Bony fish and sharks are known to be a single circulation species. The Heart What is single circulation? The Countercurrent System First, the blood in the gills flows in the opposite direction to the water passing over them.

When the water has passed over the gills, the blood is "hungry" for the oxygen that is there. The blood then becomes rich in oxygen.

Single circulation is when the blood passes through the heart once every time it circulates. Gas Exchange Gas exchange is when diffusion takes place, in the gills, only if oxygen is more concentrated in the water than in the blood. However, once the oxygen is diffused into the gills, the water surrounding the fish is depleted, and gas exchange loses its efficiency.

This is then solved by a countercurrent system. The Circulatory System When the fish is in a stable state, deoxygenated blood flows into the fisrt chamber of the heart from the body. The blood is then pumped into the second chamber of the heart, and is brought to the gills where gas exchange takes place. Once the oxygenated blood is carried back to the body by its arteries, it is then branched out into thin-walled capillaries that allow nutrients flow to a cell.

Veins are the largest vessel that brings the deoxygenated blood to the heart which repeats the cycle. Around the pyloric caeca or in that same area in fish lacking them is pancreatic tissue. In fish the pancreas is usually diffuse, not a discreet body.

As in all vertebrates, the pancreas has two digestive functions. It is the source of: The liver in fish produces bile which is stored in the gall bladder until a bolus passes the stomach, at which time the bile is expelled into the intestine. Bile contains waste products of liver activity which pass out of the fish in the feces. Bile has a digestive function in that it emulsifies lipids, greatly increasing their absorbtion in the intestine. The liver is key in the anabolism and catabolism of amino acids absorbed during digestion and is also the site of storage of food energy in the form of glycogen.

A. Digestive System