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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.
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.
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.
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.
The teeth are gigantic. The fifth gill opening is in front of the pectoral fin and spiracles are sometimes absent. They are heavily built sharks, sometimes weighing nearly twice as much as sharks of comparable length from other families. Many in the family are among the fastest-swimming fish. Megachasmidae: Megamouth sharks: 1 1
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 shark takes off because clearly, that's not what the shark was interested in. If you look at maybe something like a six-foot bull shark, just by the sheer size, it's going to do a lot more ...
Shark migration patterns may be even more complex than in birds, with many sharks covering entire ocean basins. Sharks can be highly social, remaining in large schools. Sometimes more than 100 scalloped hammerheads congregate around seamounts and islands, e.g., in the Gulf of California. [39] Cross-species social hierarchies exist.