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The Biology Department at Knox Academy put on a fish dissection annually. We do this every February during a named lunchtime. We show the dissection under our video microscope on screen. It can sometimes be quite difficult to identify the various inner organs, so we have a prepared slide show on a second screen that shows static images of what the audience should be observing.

Last year we dissected a large Sea Bass. This year, we opted for a Trout. The trout was a superb fresh rainbow. As it had come from a trout farm, it lacked many assets of a wild fish. This is fantastic for chefs, but not so for us Biologists. Today there were no parasites to be found in its digestive tract and, presumably due to its artificial diet, there was no trace of any living organisms having been consumed by the fish:(. In wild fish, their stomachs are usually filled with masticated invertebrate prey. Wild fish also usually have an infestation of parasitic worms that provide excellent viewing under the microscope. However, our fish today, was in excellent condition. The internal organs were easily identified. We looked at the heart, liver, small and large intestines. During the dissection my colleagues, helped prepare slides of fish scales, gill filaments, fish eggs and intestinal contents. These were then viewed under our high powered microscopes. We also looked at the eye, lens, optic nerve and retina. We extracted the lens and illustrated how magnification works by running it over some script. (The lens is the smallbead like object in the left of the petri dish featured below)

I will not bore you with all the Biological facts, but here are a couple that really interested the pupils.

*Fish Scales are individual structures that cover the epidermis of the creature. They are not the same as reptiles’ scales. Reptilian scales are calcified folds of the skin (epidermis). They are not individual structures.

*Fish are always slimy to touch. They become slimier once they have died. Fish secrete mucus to help them reduce the friction of the surrounding water. Once they die, the mucus secreting cells will carry on producing mucus for a number of hours. This Builds up. As the fish is not moving, the mucus is not lost. Hence, the fish becomes slimier.

I have uploaded my PowerPoint here Knox Fish Dissection

I haven’t featured any more of the J-pegs from the dissection today. The photos that supa-star Philippa took can be found here on flickr. I will add notes to these images when time allows. Beware, they are not for the squeamish.

I would like to thank my PT, Ann, colleagues Jan an Chris, for their help and support today. I would also like to say a huge thank you to our technicians, Lynn and Pamela, for there ongoing hard work and support.

*If you are a Biology and Science Teacher, please feel free to use my uploaded document and images. Any constructive feedback will be welcomed.

*The opinions expressed in these webpages are not necessarily those of any Council. The use of any copyright terms or material is not a challenge to the ownership of those materials.