| Both nektonic and benthic forms are known, although both were motile to varying degrees. |
| In fact, cephalopods themselves were the only Ordovician nektonic durophagous predators. |
| Many benthic and nektonic organisms have a larval stage that is planktonic for several months. |
| Many benthic and nektonic organisms experienced a major crisis, including calcareous and organic-walled phytoplankton. |
| This shows on one hand a strong correspondence of nektonic life with sea level changes and, on the other, the strong interrelationship of the nektonic biota. |
| The invertebrate fauna includes many planktonic forms, particularly jellyfish and the stemless crinoid Saccoma, and also nektonic organisms such as cephalopods. |
