Tardigrades are water-dwelling, eight-legged, segmented micro-animals. They were first discovered by the German zoologist Johann August Ephraim Goeze in 1773. The name Tardigrada was given three years later by the Italian biologist Lazzaro Spallanzani. They have been found everywhere: from mountain tops to the deep sea and mud volcanoes (Wikipedia).
Tardigrades, often called water bears or moss piglets, are near-microscopic animals with long, plump bodies and scrunched-up heads. They have eight legs, and hands with four to eight claws on each. While strangely cute, these tiny animals are almost indestructible and can even survive in outer space. Tardigrade is a phylum, a high-level scientific category of animal. (Humans belong in the Chordate phylum — animals with spinal cords.) There are over 1,000 known species within Tardigrade. Water bears can live just about anywhere. They prefer to live in sediment at the bottom of a lake, on moist pieces of moss or other wet environments. They can survive a wide range of temperatures and situations (https://www.livescience.com/57985-tardigrade-facts.html)
I went looking for tardigrades today in St Michael’s church graveyard in Lichfield, Staffordshire, UK. No success – sadly – so you won’t see tardigrades in the photo and video below. However, the samples I obtained from moss on gravestones, some lichen off trees and a sample from a wood chipping pile, revealed a range of life shown in the video below.
The following pictures show this problem on an example of a Zeiss Standard Optovar. The lens elements are separating and this leads to the rainbow effect. I have slightly rotated the Optovar on the spot in same lighting between pictures and you can see that the inner edge of the rainbow rotates with the rotation of the whole instrument. This would not occur if it was due to defraction of light from the glass only.
This time I used my centrifuge to concentrate the sample – snow outside/cold means number algae per ml in the water low.
Bright field images of algae x40 objective – unfortunately they show that I have some work to do aligning the optics as lot of colour fringes…there is also quite a lot of dust on the optics of this microscope – I need to give it a good clean! However, not all out of focus rings are dust – much of it is algae in different planes on this live sample.
I particularly like the second and third pictures as they show long cilia from the spherical organism.
Video from this session showing motile organisms:
Dark field using oblique illumination – set up with Zeiss Standard microscope:
I have found that the best dark field is when the fibre-optic tips are placed on the stage pointing virtually horizontally at the end of the objective.
Dark field with x10 objective, using above equipment – looks like a star field in the telescope! Can you recognise the constellations?
The above two images came directly from the camera.
The following are the same two pictures but this time I have used curves in GIMP to remove part of curve below the data and hence blacken the background:
Dark field using x40 objective – this is where I am breaking new ground with success at dark field using x40 objective. So far, using my Zeiss IM microscope, I have been able to obtain excellent dark field images using the 10x non-phase objective and a phase annulus, but the higher power objectives don’t seem to work so well using that system. I think maybe the NA on the objectives is too high compared to the NA on the condenser, but am not sure of the reason.
I found that if I varied the position of the swan neck heads to direct the light more downwards (angled the lights to point down rather than horizontally) then this varied the lighting effect. The lighting is no longer true dark field but is still interesting! Example picture below:
The following pictures are from my attempts today to try oblique illumination on the specimen using a swan-neck halogen illuminator – light shone upwards at bottom of slide obliquely. Photos below are compared to others using bright field with 10W retro-diode.com illuminator – all with Zeiss Standard microscope.
The sample is a piece of plant leaf cut from house plant in our kitchen.
The oblique illumination gives dark field effects – I picked this technique up from Micscape microscope forum (http://microscopy-uk.org.uk/mag/indexmag.html), although my oblique illuminator has currently a very red light so white balance needs to be corrected.
I have used curves function in GIMP2 to remove parts of curve without data from top and bottom of curve and in the image with lot of blue to enhance some parts curve in-between (but not done that on other images).
The pictures show swirls of cells in circular patterns and veins along the leaf.
Zeiss Standard microscope with external halogen swan-neck illuminator:
x10 objective, bright field:
x10 objective, oblique illumination, with white balance correction:
x40 objective, bright field:
x40 oblique illumination, without white balance correction:
Vorticella on a commercial stained slide, viewed using Zeiss IM microscope at different magnifications. Damian and I have previously seen Vorticella live in local pond water samples – see previous posts.
I used the Bresser MikOkular camera in “new” trinocular head (second hand from ebay) – this differs from previous trinocular head in that this is the one that is recommended in the Zeiss IM microscope handbook. I noted that the previous head, although it works, has small black ring around outside of field of view that I assume means field stop is too small for scope. This new one does not have this. This new one also provides 23mm ocular attachment on trinocular port, into which the Diagnostic Instruments adapter fits directly without needing a clamp.
I also tried out a dark field condenser on microscope today – did not work well – not sure why – so photos below are back to the phase condenser that came with the microscope, used without phase annulus (i.e. in bright field mode).
x63 objective (slide upside down so light only has to go through coverslip in this inverted microscope – 63x objective has only limited working distance). This is a panorama of 17 panes, joined using Microsoft’s Image Composite Editor: