Search results
Results from the WOW.Com Content Network
Sharks and other cartilaginous fish (skates and rays) have skeletons made of cartilage and connective tissue. Cartilage is flexible and durable, yet is about half the normal density of bone. This reduces the skeleton's weight, saving energy. [29] Because sharks do not have rib cages, they can easily be crushed under their own weight on land. [30]
Zangroniz said studies only use a few species of fish and don't represent the more than 30,000 fish species that exist. She added pain is measured in mammals on the grimace scale, often seen in ...
Some fish, such as catfish and sharks, have organs that detect weak electric potentials on the order of millivolts. [24] Other fish, like the South American electric fishes Gymnotiformes, can produce weak electric currents, which they use in navigation and social communication. In sharks, the ampullae of Lorenzini are electroreceptor organs ...
Many sharks can contract and dilate their pupils, like humans, something no teleost fish can do. Sharks have eyelids, but they do not blink because the surrounding water cleans their eyes. To protect their eyes some species have nictitating membranes. This membrane covers the eyes while hunting and when the shark is being attacked.
[1] [a] Although shoaling fish can relate to each other in a loose way, with each fish swimming and foraging somewhat independently, they are nonetheless aware of the other members of the group as shown by the way they adjust behaviour such as swimming, so as to remain close to the other fish in the group. Shoaling groups can include fish of ...
The entire body of a shark is a very efficient eating machine. Each organ has been fine-tuned for hunting and acquiring food.
Electric fish can detect electrical signals using tuberous electroreceptors which are sensitive to high-frequency stimuli. Electroreceptors exist in different forms and can be found in various parts of the body. Sharks, for example, have electroreceptors called ampullae of Lorenzini in the pores on their snouts and other zones of the head ...
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. [10] 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. [11]