Radiolaria Foraminifera Diatoms Coccolithophores

Radiolaria, Foraminifera, Diatoms, and Coccolithophores

Radiolaria Foraminifera Diatoms Coccolithophores

Why am I so fascinated with these miniscule denizens of the sea? They’re certainly not as popular and beloved as dolphins, whales or jellyfish. To see them, you need to look through a microscope, and to even get these microscopic samples in the first place you’ll need to dive to the bottom of the sea and scoop up sea bed sludge or trawl the deep sea with a special net. I have a confession to make. I’ve only seen these organisms in photographs, never in real life, a situation I hope to remedy someday.

All of these unicellular marine organisms are either planktonic, floating in the water, or they are benthic, living in the sediment on the sea bed. Radiolaria and Foraminifera are zooplankton, that is, they eat other plankton, bacteria, or dinoflagellates. Diatoms and Coccolithophores, on the other hand, are phytoplankton and photosynthesize to feed themselves.

What connects them is that they all form intricate shells, made of calcium carbonate or silicon dioxide, punctured through with holes and often studded with delicate spines. Their multiply-perforated shells are quite unlike the shells of other marine mollusks, like clams and mussels. It is known that the holes function in nutrient exchange, and in the case of the zooplankton, allow amoeboid extensions from the soft inner core of the organism to protrude out from the shell, capture food, and drag it back inside the shell to be devoured. What isn’t fully understood, however, is why there are thousands of different shell patterns among these four groups, when probably a few designs would do the job. Perhaps ecologists will be able to answer this question someday.

For artists and designers, however, these shells represent a treasure trove of inspiration. Do they have bilateral, trilateral, or radial symmetry? Are the holes regularly or unevenly spaced? Is the overall shape a spiral, a bell, a cone, or something more complex? For a 3D-print designer, the spikes present special problems. In order to survive the physics of 3D-printing, the spikes and other wire-like features have to be modeled at a minimum thickness with respect to their length. This unfortunately eliminates many of the organisms from consideration as a 3D-printable model. Yet nature seems to be free from these rules, and makes these complicated structures in abundance.

Do you have a favorite Radiolarian, Foramiferan, Diatom or Coccolithophore? Drop me a line in the comments section and maybe I’ll give the modelling a try.

2 comments
  • joseph
    Posted on October 1, 2016 at 9:21 am

    I need the functions of the holes on foraminifer

    Reply
    • Kimberly
      Posted on October 1, 2016 at 1:26 pm

      Hi Joseph,
      The pores in the foraminiferan shell, or test, are used for the uptake of food. The amoeboid cell inside the test can extrude what are called ‘pseudopods’ outside of the test to snare microorganiams and other bits of organic matter and bring them inside the cell to be digested. Thank you for your question!
      -Kimberly

      Reply

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