Evolution of Swimming
Swimming evolved a number of times in unrelated lineages, and the evolutionary pressures leading to its adoption are unknown. Supposed jellyfish fossils occur in the Ediacaran, but the first free-swimming animals appear in the Early to Middle Cambrian. These are mostly related to the arthropods, and include the Anomalocaridids, which swam by means of lateral lobes in a fashion reminiscent of today's cuttlefish. Cephalopods joined the ranks of the nekton in the late Cambrian, and chordates were probably swimming from the Early Cambrian. Many terrestrial animals retain some capacity to swim, however some have returned to the water and developed the capacities for aquatic locomotion.
Read more about this topic: Aquatic Locomotion
Famous quotes containing the words evolution of, evolution and/or swimming:
“What we think of as our sensitivity is only the higher evolution of terror in a poor dumb beast. We suffer for nothing. Our own death wish is our only real tragedy.”
—Mario Puzo (b. 1920)
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)
“The swimming hole is still in use. It has the same mudbank. It is still impossible to dress without carrying mud home in one’s inner garments. As an engineer I could devise improvements for that swimming hole. But I doubt if the decrease in mother’s grief at the homecoming of muddy boys would compensate the inherent joys of getting muddy.”
—Herbert Hoover (1874–1964)