Depth Gradients
Species diversity in the deepsea has been largely underestimated until recently (e.g., Briggs 1994: total marine diversity less than 200,000 species). Although our knowledge is still very fragmentary, some recent studies appear to suggest much greater species numbers (e.g., Grassle and Maciolek 1992: 10 million macroinvertebrates in soft bottom sediments of the deepsea). Further studies must show whether this can be verified. A rich diversity in the deepsea can be explained by the hypothesis of effective evolutionary time: although temperatures are low, conditions have been more or less equal over large time spans, certainly much larger than in most or all surface waters.
Read more about this topic: Effective Evolutionary Time
Famous quotes containing the word depth:
“Now as at all times I can see in the mind’s eye,
In their stiff, painted clothes, the pale unsatisfied ones
Appear and disappear in the blue depth of the sky”
—William Butler Yeats (1865–1939)