Our Experiment
In our experiment we decided to dissect a fish (trout more specifically) in order to observe the positioning of its internal organs, how it is adapted to its environment and which features allow it to survive underwater.
We started off by simply observing its external characteristics. Its shape was highly streamlined in order to allow it maximum speed in water. We noticed that it had approximately 6 fins, placed in different parts of the body, with the dorsal and frontal fins being relatively small in comparison to the rest of the body. The skin, particularly on the head, was slimy, to allow the trout to swim through the water easily and to prevent fungal infections on the skin surface. We then turned our focus to the head of the fish, where there were fewer scales to be observed and the skin was harder. In addition to this, we found that the scales at the top of trout are far darker than the scales at the bottom. Above the mouth we observed two small, round holes that we identified as nostrils. We then decided to examine the mouth where we found several small, pointy teeth and a spiked tongue. Once we had finished observing the outer appearance, we began to dissect it. We had a slight difficulty in penetrating the skin with the scalpel, proving that the skin was harder than we originally believed it to be. We made the incision straight down the centre of the fish and could observe the digestive system, particularly the stomach. After cutting past a few membranes, we located the liver near the head of the fish, both a dark red colour, before finally examining the swim bladder. With our second fish, we began to examine the back bone of the trout. Contrary to our assumptions, the bone was located lower down. We then began to inspect the gills in more detail by removing the operculum, under which we discovered 3 serrated gill arches with compressed gill filaments. After removing one of the gill arches and placing it in water, we found that the gill expanded. Another observation that we made was that the gills were very red in colour, indicating that many capillaries were located there. The final thing we closely examined was the skin of the fish taken from its sides and how the proportion of fat it had decreased further from the head of the fish, with almost fat lining the skin near the tail. |