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Spiracle of a bluespotted ribbontail ray, Taeniura lymma. Spiracles (/ ˈ s p ɪr ə k əl, ˈ s p aɪ-/ [1] [2]) are openings on the surface of some animals, which usually lead to respiratory systems. Spiracle of a shark (bighead spurdog, Squalus bucephalus) The spiracle is a small hole behind each eye that opens to the mouth in some fish.
Shark Anatomy (50693674756) The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. In the shark anatomy image, it depicts the beginning half of the shark, including the gills. The shark gills are especially important and were evolved from the chordate pharyngeal gill slits synapomorphy.
Spiracles are reduced or missing in active pelagic sharks. [1] While the shark is moving, water passes through the mouth and over the gills in a process known as "ram ventilation". [ 2 ] While at rest, most sharks pump water over their gills to ensure a constant supply of oxygenated water.
Most sharks rely on ram ventilation, forcing water into the mouth and over the gills by rapidly swimming forward. In slow-moving or bottom-dwelling species, especially among skates and rays, the spiracle may be enlarged, and the fish breathes by sucking water through this opening, instead of through the mouth. [9]
The value of shark fins for shark fin soup has led to an increase in shark catches where usually only the fins are taken, while the rest of the shark is discarded, typically into the sea; health concerns about BMAA in the fins now exists regarding consumption of the soup A 4.3-metre (14 ft), 540-kilogram (1,200 lb) tiger shark caught in Kāne ...
In most rajoids, water for breathing is taken in through the spiracles rather than through the mouth and exits through the gill slits. Most species swim by undulating their enlarged pectoral fins, but the guitarfish propel themselves through the water with sideways movements of their tail and caudal fin.
Most batoids have a flat, disk-like body, with the exception of the guitarfishes and sawfishes, while most sharks have a spindle-shaped body. Many species of batoid have developed their pectoral fins into broad flat wing-like appendages. The anal fin is absent. The eyes and spiracles are located on top of the head.
Pores are concentrated in the skin around the snout and mouth of sharks and rays, as well as the anterior nasal flap, barbel, circumnarial fold and lower labial furrow. [10] Canal size typically corresponds to the body size of the animal but the number of ampullae remains the same. The canals of the ampullae of Lorenzini can be pored or non-pored.