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:
“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)
“Heaven and hell suppose two distinct species of men, the good and the bad. But the greatest part of mankind float betwixt vice and virtue.”
—David Hume (1711–1776)
“Our species successfully raised children for tens of thousands of years before the first person wrote down the word “psychology.” The fundamental skills needed to be a parent are within us. All we’re really doing is fine-tuning a process that’s already remarkably successful.”
—Lawrence Kutner (20th century)