A plethora of life just out of sight

May 13, 2017 • 6:48 PM UTC

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sleafmye

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Hello Foldscope community, my name is Shannon and I am a graduate student in CSU Monterey Bay’s Applied Marine and Watershed Science program. As part of my Marine Ecology class, we’ve had the wonderful opportunity to use Foldscopes to explore the amazing complexity of microscopic life that is right before us and yet out of sight. The next few posts will chronicle my journey into this microbiological world using this brilliant tool that I feel holds immense potential to engage ordinary people in a realm of scientific inquiry that is often cost prohibitive.

Today’s post involves an introduction to plankton tows: capturing organisms of a certain size by dragging a net through the water. In this case, we conducted a tow from the dock at Monterey’s Coastguard Jetty. We used a 202 micron net towed for approximately 25 meters (repeated a few times), and then poured the contents through a 60 micron sieve. We returned to our professor’s lab with a jar of what appeared to be plain seawater, but soon realized was full of hundreds if not thousands of zooplankton specimens!

The life cycle of many marine species involves what is known as a Pelagic Larval Duration (PLD), or a period during which time larvae drift in the ocean’s currents before settling or establishing in certain environments based on both physical and chemical cues. There is still much to learn about exactly how different species navigate this vulnerable period of development, but through the use of novel instruments like small robotic drifters, marine scientists are slowly teasing apart influential mechanisms in this process. In addition to the larvae of species that one day grow into forms that can assert their spatial position in the marine environment, there are many organisms that remain beyond the veil of human sight for the duration of their lives and yet form an integral linkage in marine food webs.
The following pictures illustrate a few of the many specimens that our class collected during what was my first experience with plankton tows! This first set of three images (head, abdominal, and tail) shows what I believe is some type of decapod due to the stalked eyes and approximately ten appendages. Decapods are crustaceans that include true shrimps, and the larvae of crabs and lobsters.

I now turn to perhaps the most important, ubiquitous, and abundant zooplankton groups in the world , copepods! Their importance in marine food webs is tied to their role in linking primary and secondary production. Copepods eat phytoplankton and detritus and are in turn consumed by small fish and other secondary consumers, and on the cycle goes.

They undergo numerous developmental stages, from naupliar (the smallest) to copepodite (nearing adult form), during which time they add various segments to the three major morphological regions of their bodies: the cephalosome (head), the prosome (the bulk of their body, which includes the cephalosome), and the urosome (the tail)–see The Light and Smith Manual, 4th Ed. for an exhaustive treatise on intertidal invertebrates. My guess is that this particular copepod belongs to the Calanoida order due to its large prosome. Free-swimming copepods such as this one (I’m assuming) use their antennae to pull themselves through the water.
My last specimen is an unknown, but appears to be a seaweed fragment in which individual cells can be seen.

This first experience using Foldscopes was incredibly rewarding and revealed the amazing amount of organisms in the marine environment that we just can’t see without magnification. Despite my previous knowledge that the ocean is full of tiny organisms at varying stages of development, this experience really brought that theoretical understanding down to a level of lived experience that I will carry with me and will definitely inspire future inquiry!

A plethora of life just out of sight

sleafmye

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