Osmoregulation in Cyclograpsus and Plagusia crab species
Hartzer, A.M, 19971613, First year BSc student, Stellenbosch University, South Africa
Abstract
Osmoregulatory processes within two crab species are investigated in this practical. The Plagusia, an infratidal species, and Cyclograosus, an intertidal species, are investigated to determine which is an osmoregulator and which is an osmoconformer. The haemolymph was extracted after allowing the species to acclimatize to varying concentrations of seawater. The comparative melting-point technique was used in the experiment where capillary tubes were used to collect samples of the seawater and blood, then frozen and put into an alcohol bath. The melting points of each sample was then observed …show more content…
Both species were acclimated to varying dilutions of seawater prior to extraction of haemolymph. The experiment was completed in groups of 4 people. The container, which held the capillary tubes, was filled to about 70% with the alcohol solution provided. Vaseline was placed along the two long sides of the capillary holder to anchor the capillary tubes. The 14 capillary tubes were then filled with the samples of seawater or blood. Only a small amount of the sample fluid was loaded into the capillary tube, about 3mm length-wise, the minimum amount to fill the cross section of the tube. Each capillary tube was dipped into the sample fluid to allow the capillary action to draw in the liquid. Capillary tubes 1-5 were filled with the different concentrations of seawater: 100%, 75%, 50%, 25% and distilled water, respectively. Capillary tubes 6-10 were filled with the different concentrations of Cyclograpsus blood (diluted with seawater): 100%, 80%, 60%, 40% and 20%, respectively. Capillary tubes 11-14 were filled with the different concentrations of Plagusia blood (diluted with seawater): 100%, 80%, 70% and 60% respectively. If too much of the sample liquid entered the capillary tube, some was removed by lightly tapping the tube on a paper towel. In each of the capillary tubes the sample liquid was moved to the middle of the tube by lightly tapping it; once the liquid was in the middle both ends of the tube were sealed by plugging both ends with some Vaseline. The capillary tubes were then arranged in sequence along the tube holder with a space between the 3 groups. The alcohol bath was then prepared by placing dry ice into it in order to lower the temperature to around -15°C. Gloves or paper towels were used to handle the dry ice. Temperature was checked with a thermometer once all the ice had melted. The prepared bath was then
Hartzer, A.M, 19971613, First year BSc student, Stellenbosch University, South Africa
Abstract
Osmoregulatory processes within two crab species are investigated in this practical. The Plagusia, an infratidal species, and Cyclograosus, an intertidal species, are investigated to determine which is an osmoregulator and which is an osmoconformer. The haemolymph was extracted after allowing the species to acclimatize to varying concentrations of seawater. The comparative melting-point technique was used in the experiment where capillary tubes were used to collect samples of the seawater and blood, then frozen and put into an alcohol bath. The melting points of each sample was then observed …show more content…
Both species were acclimated to varying dilutions of seawater prior to extraction of haemolymph. The experiment was completed in groups of 4 people. The container, which held the capillary tubes, was filled to about 70% with the alcohol solution provided. Vaseline was placed along the two long sides of the capillary holder to anchor the capillary tubes. The 14 capillary tubes were then filled with the samples of seawater or blood. Only a small amount of the sample fluid was loaded into the capillary tube, about 3mm length-wise, the minimum amount to fill the cross section of the tube. Each capillary tube was dipped into the sample fluid to allow the capillary action to draw in the liquid. Capillary tubes 1-5 were filled with the different concentrations of seawater: 100%, 75%, 50%, 25% and distilled water, respectively. Capillary tubes 6-10 were filled with the different concentrations of Cyclograpsus blood (diluted with seawater): 100%, 80%, 60%, 40% and 20%, respectively. Capillary tubes 11-14 were filled with the different concentrations of Plagusia blood (diluted with seawater): 100%, 80%, 70% and 60% respectively. If too much of the sample liquid entered the capillary tube, some was removed by lightly tapping the tube on a paper towel. In each of the capillary tubes the sample liquid was moved to the middle of the tube by lightly tapping it; once the liquid was in the middle both ends of the tube were sealed by plugging both ends with some Vaseline. The capillary tubes were then arranged in sequence along the tube holder with a space between the 3 groups. The alcohol bath was then prepared by placing dry ice into it in order to lower the temperature to around -15°C. Gloves or paper towels were used to handle the dry ice. Temperature was checked with a thermometer once all the ice had melted. The prepared bath was then