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:
“Prostitution is the most hideous of the afflictions produced by the unequal distribution of the world’s goods; this infamy stigmatizes the human species and bears witness against the social organization far more than does crime.”
—Flora Tristan (1803–1844)
“If there is a species which is more maltreated than children, then it must be their toys, which they handle in an incredibly off-hand manner.... Toys are thus the end point in that long chain in which all the conditions of despotic high-handedness are in play which enchain beings one to another, from one species to another—cruel divinities to their sacrificial victims, from masters to slaves, from adults to children, and from children to their objects.”
—Jean Baudrillard (b. 1929)
“A man, to be greatly good, must imagine intensely and comprehensively; he must put himself in the place of another and of many others; the pains and pleasures of his species must become his own.”
—Percy Bysshe Shelley (1792–1822)