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The water vascular system is a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. [1] The system is composed of canals connecting numerous tube feet. Echinoderms move by alternately contracting muscles that force water into the tube feet, causing them to ...
In fish, the system has only one circuit, with the blood being pumped through the capillaries of the gills and on to the capillaries of the body tissues. This is known as single cycle circulation. The heart of fish is therefore only a single pump (consisting of two chambers). Fish have a closed-loop circulatory system.
Many fish have a number of small outpocketings, called pyloric caeca, along their intestine. The purpose of the caeca is to increase the overall surface area of the intestines, thereby increasing the absorption of nutrients. [32] [33] The number of pyloric caeca varies widely between species, and in some species of fish no caeca are present at all.
In many fish, a rete mirabile helps fill the swim bladder with oxygen, increasing the fish's buoyancy. The rete mirabile is an essential [ 8 ] part of the system that pumps dissolved oxygen from a low partial pressure ( P O 2 {\displaystyle {P_{\rm {O_{2}}}}} ) of 0.2 atmospheres into a gas filled bladder that is at a pressure of hundreds of ...
The hagfish circulatory system also includes multiple accessory pumps throughout the body, which are considered auxiliary "hearts". [39] Hagfish are the only known vertebrates with osmoregulation isosmotic to their external environment. Their renal function remains poorly described. There is a hypothesis that they excrete ions in bile salts. [42]
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. [3] More recently, the class was known as Pelecypoda, meaning "axe-foot" (based on the shape of the foot of the animal when extended).
They generally range in size from 15 to 25 cm (6 to 10 in), with the largest species, the giant cuttlefish (Sepia apama), reaching 50 cm (20 in) in mantle length and over 10.5 kg (23 lb) in mass. [1] Cuttlefish eat small molluscs, crabs, shrimp, fish, octopuses, worms, and other cuttlefish.
The maximum load of organisms that can be cultured in a raceway system depends on the species, and particularly on the size of the species. For trout, stocking rates of 30 to 50 kg/m 3 are normal at the end of a rearing cycle, while for marine species, such as sea bass and sea bream, the achievable load is lower, between 15 and 20 kg/m 3 .