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.
Read more about this topic: Swim Bladder
Famous quotes containing the word species:
“Under the species of Syndicalism and Fascism there appears for the first time in Europe a type of man who does not want to give reasons or to be right, but simply shows himself resolved to impose his opinions.”
—José Ortega Y Gasset (1883–1955)
“There are minds so impatient of inferiority that their gratitude is a species of revenge, and they return benefits, not because recompense is a pleasure, but because obligation is a pain.”
—Samuel Johnson (1709–1784)
“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)