Trott, T.J. 2004. Cobscook Bay inventory: a historical checklist of marineinvertebrates spanning 162 years. Northeastern Naturalist (Special Issue 2): 261
Functional Biology of Scyphozoa. London: Chapman and Hall. : 68–206. MarineInvertebrates of Bermuda (页面存档备份,存于互联网档案馆) Animal Diversity Web (页面存档备份,存于互联网档案馆)
背景灭绝率在各个地质年代之间有不同的变化。不同生物种群的灭绝速率也不一致。 Thackeray, J. Francis. Rates of Extinction in MarineInvertebrates: Further Comparison Between Background and Mass Extinctions. Paleobiology