Describe at least 3 of the adaptations used by plankton in their efforts to remain near the surface. ...

Plankton employ a number of adaptations that either slow down their sinking rate or keep them at the surface. Many of these animals are small in comparison to animals from other habitats. Small bodies mean that the surface area-to-volume ratio will be maximized, thus leading to a relative increase in surface area, which leads to increased friction with the water and slower sinking rates. Zooplankton and phytoplankton also increase their surface areas by having many long spines and projections that increase surface area without substantially increasing volume or density. Some planktonic organisms reduce their density below that of seawater by secreting oil or lipid in their tissues. Other animals reduce their density by substituting water for organic matter in their tissues. A few phytoplankton and many zooplankton are capable of limited vertical movement in the water column.