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Instead, the gills are contained in spherical pouches, with a circular opening to the outside. Like the gill slits of higher fish, each pouch contains two gills. In some cases, the openings may be fused together, effectively forming an operculum. Lampreys have seven pairs of pouches, while hagfishes may have six to fourteen, depending on the ...
Many aquatic animals have developed gills for respiration which are specifically adapted to their function. In fish, for example, they have: A large surface area to allow as much oxygen to enter the gills as possible because more of the gas comes into contact with the membrane; Good blood supply to maintain the concentration gradient needed
The blood carries oxygen to other parts of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians.
Oxygen diffuses into water from air and therefore the top layer of water in contact with air contains more oxygen. This is true only in stagnant water; in running water all layers are mixed together and oxygen levels are the same throughout the water column. One environment where ASR often takes place is tidepools, particularly at night. [34]
The combination of gases in the bladder varies. In shallow water fish, the ratios closely approximate that of the atmosphere, while deep sea fish tend to have higher percentages of oxygen. For instance, the eel Synaphobranchus has been observed to have 75.1% oxygen, 20.5% nitrogen, 3.1% carbon dioxide, and 0.4% argon in its swim bladder.
Many marsupials have a permanent bag, whereas in others the pouch develops during gestation, as with the shrew opossum, where the young are hidden only by skin folds or in the fur of the mother. The arrangement of the pouch is variable to allow the offspring to receive maximum protection.
Monkeys have open cheek pouches within the oral cavity, but they open out in some rodents of America. Hence the name "diplostomes" is associated with them, which means "two mouths." In some rodents, such as hamsters , the cheek pouches are remarkably developed; they form two bags ranging from the mouth to the front of the shoulders.
This oxygen store has three components; oxygen contained in the air in the lungs, oxygen stored by haemoglobin in the blood, and by myoglobin, in muscle tissue, The muscle and blood of diving vertebrates have greater concentrations of haemoglobin and myoglobin than terrestrial animals. Myoglobin concentration in locomotor muscles of diving ...