How did I record this?
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Please enjoy this video made using my Razer Phone 2 and Nikon Eclipse E200 Student Microscope at 40x, 100x and 400x (2x, 4x, 10x, and 40x objectives). The Razer Phone 2 is recording at 2x magnification, 60fps at 4K resolution.
Wet mounting
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I used a United Scientific triple concavity glass slide (www.amazon.ca/...) and pipetted this planarian with some of its pond water into the middle concavity. Finally, I covered it with a glass coverslip.
Darkfield
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The background is black for some 40x segments because I used a microscopy technique called "darkfield" (or dark-field/dark field). This was achieved using a Nikon Ph2 phase annulus placed inside a Nikon Phase Condenser for the Eclipse E200.
Contents of the video
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"Planarians are a group of nonparasitic, free-living flatworms. Dugesia is a planarian that lives in freshwater lakes, streams, and ponds, where it feeds on small living or dead organisms. A planarian captures food by wrapping itself around the prey, entangling it in slime, and pinning it down. Then, a muscular pharynx is extended through the mouth and a sucking motion takes pieces of the prey into the pharynx. The pharynx leads to a three-branched gastrovascular cavity, in which digestion is both extracellular and intracellular (Fig. 28.12a). The digestive system delivers nutrients and oxygen to the cells; the animal has no circulatory system or respiratory system. Waste molecules exit through the mouth...
Planarians usually reproduce sexually. They are monoecious (hermaphroditic), which means that they possess both male and female sex organs and gametes in a single individual (Fig. 28.12c)...
Planarians also can reproduce asexually via regeneration. The tail portion of the planaria breaks off, and each part grows into a new worm. Because planarians have the ability to regenerate, they have been the subject of a field of research called regenerative medicine...
The nervous system of planarians is called a ladder-type, because the two lateral nerve cords plus transverse nerves look like a ladder (Fig. 28.12d). Paired ganglia, or collections of nerve cells, function as a primitive brain.
Planarians are bilaterally symmetrical and exhibit cephalization" (Mader & Windelspecht, 2016, p. 525).
Ocular Micrometer Calibration
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The small ruler visible in the video is called an ocular micrometer. It is calibrated using a special slide called a "slide micrometer"--clever!
The calibration I performed on Sunday June 9, 2019 yielded the approximate values below. Between each whole number on the ocular micrometer (called an "ocular unit" divided into 10 "ocular divisions"), there are:
20x: 0.500 mm (approx.) per ocular unit
40x: 0.250 mm (approx.) per ocular unit
100x: 0.099 mm (approx.) per ocular unit
400x: 0.025 mm (approx.) per ocular unit
You can use these calibrations to give you a rough idea of how large any object you see in the videos is, you only need to use a little math! Cool right?
Music
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"Becoming Insane" by Infected Mushroom 😂🤣
Read more!
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"planarian site:edu": www.google.com...
micro.magnet.f...
www.devbio.biol...
now.tufts.edu/...
wi.mit.edu/news...
news.illinois....
Nice incomplete image: hpsrepository....
References
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Mader, S., & Windelspecht, M. (2016). Biology (12th edition). New York, NY: McGraw-Hill Education.