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By measuring blood chemistry samples when the shark is immobile, it has been suggested that tonic immobility can actually put stress on the shark, and reduce breathing efficiency. Others think sharks have a series of compensatory mechanisms that work to increase respiration rates and lower stress.
Leydig's organ (named after the German histologist Franz Leydig who first described it in 1857) is a unique structure found only in some, but not all, elasmobranchs (sharks and rays). Nestled along the top and bottom of the esophagus , it produces red blood cells , as do the spleen and special tissue around the gonads . [ 1 ]
The shark heart's main importance is providing oxygenated blood to the entire body while filtering out the deoxygenated blood. [15] A shark's spleen is also incredibly important because it is where red blood cells (RBC's) are derived and is also where the immune system functions to fight off pathogens. [16]
This is most commonly found among sharks such as the grey nurse shark, but has also been reported for Nomorhamphus ebrardtii. [ 12 ] Hemotrophic (blood eating) viviparity means embryos develop in the female's (or male's) oviduct and nutrients are provided directly by the parent, typically via a structure similar to, or analogous to the placenta ...
Salt gland of a bird and its inner structure Magellanic penguin. The avian salt gland has two main ducts: a medial and a lateral. Salt gland activations occurs from increased osmolarity in the blood, stimulating the hypothalamic information processing, sending a signal through the parasympathetic nerve activating vasodilation, the release of hormones (acetylcholine and vasoactive intestinal ...
As a part of the cell's natural division process, excess cells may be generated during normal growth, development, or tissue repair after illness or an injury. Only a fraction of these new cells will stay and become mature, while the rest will die and be cleared by the body's immune system.
Sharks are much more sensitive to electric fields than electroreceptive freshwater fish, and indeed than any other animal, with a threshold of sensitivity as low as 5 nV/cm. The collagen jelly, a hydrogel , that fills the ampullae canals has one of the highest proton conductivity capabilities of any biological material.