Species
Swim bladders are only found in ray-finned fish. In the embryonic stages some species have lost the swim bladder again, mostly bottom dwellers like the weather fish. Other fish like the Opah and the Pomfret use their pectoral fins to swim and balance the weight of the head to keep a horizontal position. The normally bottom dwelling sea robin can use their pectoral fins to produce lift while swimming. The cartilaginous fish (e.g. sharks and rays) and lobe-finned fish do not have swim bladders. They can control their depth only by swimming (using dynamic lift); others store fats or oils for the purpose.
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Famous quotes containing the word species:
“As kings are begotten and born like other men, it is to be presumed that they are of the human species; and perhaps, had they the same education, they might prove like other men. But, flattered from their cradles, their hearts are corrupted, and their heads are turned, so that they seem to be a species by themselves.... Flattery cannot be too strong for them; drunk with it from their infancy, like old drinkers, they require dreams.”
—Philip Dormer Stanhope, 4th Earl Chesterfield (1694–1773)
“If we consider the superiority of the human species, the size of its brain, its powers of thinking, language and organization, we can say this: were there the slightest possibility that another rival or superior species might appear, on earth or elsewhere, man would use every means at his disposal to destroy it.”
—Jean Baudrillard (b. 1929)
“Both classically- and romantically-minded spirits—inasmuch as these two species always exist—occupy themselves with a vision of the future: but the former do so out of a strength of their age, the latter out of its weakness.”
—Friedrich Nietzsche (1844–1900)