• Posted on March 5, 2013 6:51 pm
    By Chris
    Bee sting showing barbs under the electron microscope

    Today’s Diary Entry is sponsored by Spikes World

    What a day, to be honest I am sitting here wondering how I could possibly fit it all into my 500 word daily target. It’s a shame really that I have 3 subjects that I could talk about for hours in a single day and other days where I am really left with not much to say at all. I am actually considering splitting my diary for Tuesdays over both Tuesday and Thursday which will let me go into more¬† depth, and give me more to talk about Thursdays – what do you guys think of this?

    Well today started with diseases of bee’s, and the major part of it went to look at the difference in anatomy of bee’s. Now this is pretty interesting as the bee is so small yet has several differences, the first of which is that it has an open circulatory system. Basically instead of having capillaries to carry the blood to organs the heart pumps it directly into body cavities to surround organs before it then diffuses back to the circulatory system. In fact even bee blood itself is different as the bee does not have erythrocytes (red blood cells); instead it has something known as haemolymph which is made up of haemocytes and is a yellowish colour. The bee also has several specialised glands which help produce the honey and wax, in addition to the poison gland which is located next to the stinger.

    It’s pretty common knowledge that a bee with die after it stings you, whats not so common is the understanding of why this is. Below you can see an image of the bee sting under the electron microscope and see that it has barbs each side which hook into the skin when a bee stings you. Now these means it takes time for the bee to remove it after however our first instinct is the brush the bee of us, and when we do this the stinger and attached poison glands are ripped from the bee’s abdomen causing its death.

    Bee sting showing barbs under the electron microscope

    Bee sting showing barbs under the electron microscope (via http://www5.pbrc.hawaii.edu/microangela/bsting.htm)

    Onto fish now today we started looking at the effect of the environmental conditions on the fish. Now the environment includes both the physical and chemical characteristics of the water that is home to the fish. Whether that is the temperature, viscosity, density, pH, salinity, oxygen saturation or even the electric conductivity.Today I will look at the oxygen in terms of the environmental conditions as without it there is no life. Fish take oxygen dissolved within the water into their body through the gills where it then enters the blood. Now the temperature of the water does really affect the level of oxygen that can be saturated within the water (the graph below is for an indication only and does not have a complete dataset!).

    Oxygen saturation vs the temperature of the water

    This chart is produced from an incomplete dataset, consult other sources for full values!

    As you can see water at 100 degrees celsius cannot contain oxygen, ideally most fish live in conditions with the temperature between 15 – 30 degrees celsius. Now oxygen enters waters through two routes, the diffusion of oxygen from the water/air barrier at the surface, and through the process of photosynthesis. The majority of oxygen in water does actually come from photosynthesis of plant matter, this requires sunlight so on average there is 12 hours where photosynthesis does not take place. This leads us into a daily cycle of variation in the oxygen concentration with the oxygen level in water being lowest just before dawn, and highest at sunset.

    During winter when the days are shorter (so less light), and with many water areas being frozen (preventing the diffusion of oxygen into the water) many fish enter a low metabolic state (aka use less oxygen to live) in the bottom layer of the water. During this period of low energy fish are extremely vulnerable to disease. On that note I will leave you for today!

    Posted in categories: Vet School Diary
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