Use a plankton net.
telescope
they feed on planktons. The planktons which serve as their food filters the water that enters to a porifera's pores and this microorganisms (planktons) serve as their food.
telescope
telescope
Holoplankton and meroplankton are types of planktons found in the oceans. Holoplankton are planktons for their entire lives, while meroplanktons are planktons for only part of their lives.
Electronic microscope
At the Age of Exploration they used telescope to observe stars.
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Planktons
planktons
planktons
A Periscope or Radar