What Type Of Microscope

[tarynkay14]

You are a marine biologist who wants to study what type of zooplankton (microscopic animals that live in the ocean and feed larger organisms) inhabit a particular area of the Pacific Ocean. You have taken your samples, but now need to collect your data. What advantage would using a compound light microscope have over using a dissecting microscope?

[frugalfred]

The magnification of a compound light microscope is much greater than a dissecting microscope, the latter having a power of circa 50x; the former could magnify as much as 500x.

[Buenchico]

Dissecting microscopes shine light ONTO specimens. Zooplankton would appear as little more than silhouettes if viewed by such a technique.

Compound light microscopes shine light THROUGH specimens, enabling their interior structures to become clearly visible, like this:
http://24.media.tumblr.com/tumblr_m2ug3dZILH1r2urvgo1_500.jpg

[jomifl]

Dissecting (stereo) microscopes can use reflected or transmitted light and give adequate magnification for identifying zooplankton. I used to do this, trust me.

[jomifl]

Buenchico, you don't get silhouettes from reflected light.

[Buenchico]

>>>you don't get silhouettes from reflected light

True enough, Jomifl.

I was simply trying to indicate that only the general shape of the specimen would be visible, rather than a great deal of detail.

So how should Tarynkay14 answer the question which appears to have been set by his/her course tutor then?

[jomifl]

Buenchico, there are a lot of assumptions in the question, not least of which is he assumption that the person answering the question knows whether the samples are alive or have been killed and preserved and have been stained either before or after death. The morphological structures used for identification are usually external so a dissecting microscope of 50x would be suitable especially if it is necessary to count as well as identify the specimens in the sample. It might on occasion be necessary to use a higher power compound microscope to distinguish between closely related species (but not in the same sample) but if you had to choose only one I would go for a dissecting/stero microscope without question. Modern good quality microscopes are more than up to the job.

[Peter Pedant]

Incredible - I hadnt realised we had a marine biologist on our books.


I used to think my previous life as a tech in a germ warfare lab was craziest previous job.

Boys Boys I think you should recall this had all the hall marks of course work....

[jomifl]

PP, It does have all the hallmarks of homework or coursework which is why my first answer was fairly minimal, my later reply was really to Buenchico. As you can see evolution is working well and every ecological niche is being filled. I wonder if there is a vegan submarine spiritualist available for the more esoteric questions.

[Peter Pedant]

It sudduv came up last week
my crazy past - I thought everyone knew that sarin persists in the nooks of shrapnel for years - but apparently they don't