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Dorsal fin diagram with landmarks labeled. Fins allow the sharks to be able to guide and lift themselves. Most sharks have eight fins: a pair of pectoral fins, a pair of pelvic fins, two dorsal fins, an anal fin, and a caudal fin. Pectoral fins are stiff, which enables downward movement, lift, and guidance.
The shape of the hammerhead shark's head may enhance olfaction by spacing the nostrils further apart. Sharks have keen olfactory senses, located in the short duct (which is not fused, unlike bony fish) between the anterior and posterior nasal openings, with some species able to detect as little as one part per million of blood in seawater. [61]
Fish typically have quite small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. [59] However, some fish have relatively large brains, most notably mormyrids and sharks, which have brains about as massive relative to body weight as birds and marsupials .
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.
This gives these areas much of the same strength found in the bony tissue found in other animals. Generally sharks have only one layer of tesserae, but the jaws of large specimens, such as the bull shark, tiger shark, and the great white shark, have two to three layers or more, depending on
The entire body of a shark is a very efficient eating machine. Each organ has been fine-tuned for hunting and acquiring food. Sharks are built to feed: Here's why they are the ultimate eating machines
The following outline is provided as an overview of and topical guide to sharks: Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 440 million years ago, before the time of the dinosaurs. [1]
Sharks and rays typically have five pairs of gill slits that open directly to the outside of the body, though some more primitive sharks have six or seven pairs. Adjacent slits are separated by a cartilaginous gill arch from which projects a long sheet-like septum , partly supported by a further piece of cartilage called the gill ray.