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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 gill slits lie in a row behind the head. The anterior edge of a gill slit is motile, moving outward to allow water to exit, but closing to prevent reverse flow. A modified slit, called a spiracle , lies just behind the eye , which assists the shark with taking in water during respiration and plays a major role in bottom–dwelling sharks.
Spiracles are cartilaginous structures located on the top of a shark's head to draw oxygenated water from above in addition to it passing over the gills. [ 41 ] A ventral dissection of a pregnant female dogshark exposing its internal gill slits and internal spiracles.
The shark is able to breathe with these gills by swimming or staying in a current. The Pacific spiny dogfish also has a special feature called a spiracle. These are gills that are behind the eyes of the shark that give oxygen to the eyes and brain. It is also used to breathe while resting or eating. [20]
A spiracle is a small hole found behind each eye. These can be tiny and circular, such as found on the nurse shark (Ginglymostoma cirratum), to extended and slit-like, such as found on the wobbegongs (Orectolobidae). Many larger, pelagic species, such as the mackerel sharks (Lamnidae) and the thresher sharks (Alopiidae), no longer possess them.
Spiracles are reduced or missing in active pelagic sharks. [28] While the shark is moving, water passes through the mouth and over the gills in a process known as "ram ventilation". While at rest, most sharks pump water over their gills to ensure a constant supply of oxygenated water.
A spiracle occurs beneath each eye which is used in respiration. The only exception to this rule is the whale shark, the spiracles of which are situated just behind the eyes. [3] Carpet sharks derive their common name from the fact that many species have a mottled appearance with intricate patterns reminiscent of carpet designs.
The horn shark (Heterodontus francisci) is a species of bullhead shark, ... Each eye lacks a nictitating membrane and is followed by a tiny spiracle.