The species chosen for this experiment ( or instead set of experiments ) is Melarhaphe neritoides. This is a really common ( little ) species of snail found distributed along the bouldery Maltese shores. It is listed in the Phylum Mollusca ( Class Gastropoda ) and grows to approximately merely under 1cm. Its sides are level ( unlike the more common rounded shell found amongst molluscs ) and has a high pointed steeple. An operculum covers an egg-shaped aperture and a white periostracum leads to the dark blue/black shell.
Its niche is located in a really specific stretch on the shore labelled the supralittoral zone. This is that country located merely above the high tide grade. It is non submerged but is often splashed by sea spray when it is windy/stormy ( in fact it is besides known as the splash or spray zone ) . It is an unforgiving environment and beings populating here must be really good adapted to its instability.
The Melarhaphe neritoides snail must be able to defy ; high temperatures, fresh water, salt and seawater H2O, dehydration and exposure to air and of class any shore line animate beings which might feed upon the snail. In the summer months, the sea round the Maltese islands is really unagitated and the snail ‘s environment is seldom wetted. Besides the snail lives in direct contact with the difficult rocky surface which reaches high temperatures up to 50 grades easy ( which for most beings this would be deadly ) . On the other manus during the winter months, storms are frequent and wave action is really violent on the supralittoral zone. Not merely this but when there are no moving ridges, pools of fresh H2O may organize in these bouldery spots which for most animals adapted to a salty ( high H2O potency ) environment will do osmotic jobs. As opposed to the summer months, the temperature of the stones in winter falls drastically some times even below stop deading point. In fact as the mollusk is really good adapted to this environment, it is the dominant macro-faunal being found at that place. To suit such drastic alterations in its environment, Melarhaphe neritoides has many behavioral versions.
Such versions include ; going inactive, taking safety in pits/rocky overhangs, aggregating in groups and going active merely when conditions are suited. To be able to accurately avoid the abrasiveness of the environment, the mollusk must hold some sort of sense as to when to really get down aestivation periods or when to come out of them, which topographic point is suited ( offers plenty protection ) to take safety in etc. It is these behavioral versions that this experiment investigates. A set of different home grounds and conditions are prepared and a figure of snails tested to see their reaction and penchant.
Such an experiment must be conducted every bit accurately as possible as there are many factors which induce mistakes. In fact the trial subjects where freshly caught and a figure ( 10 ) of persons were tested with each method to guarantee useable and interpretable informations. Besides the persons tested where seen to be approximately 0.7mm in tallness. This is the tallness of juveniles non excessively immature or excessively old as it is in this portion of its life clip in which an animate being is most likely traveling to react as expected in persons seen in the wild ( as old or immature specimens may be less active or inhabit different parts of the environment ) .
Petri dishes Graph paper Plastic fish tanksRuler Timer Acrylic plates ( drilled )Measuring cylinder Black bags Glass Rod Gravel Fine Sand Coarse Sand Circular glass trough
Calcium Chloride Sea Water Distilled H2OVaseline lubricating oil Blu-Tack
Experiment.1A fictile Petri-dish was partitioned by agencies of thin plastic into 3 separate parts.
One portion filled with all right sand, another with coarse sand and the other with crushed rock. Ten inactive snails were scattered across on these 3 different sabstrates and any motion made noted every 1,2,6,24,36 hour.Experiment.
2Two indistinguishable Petri dishes had their underside ruled to organize a 4×4 grid at 1 centimeter intervals. One snail was placed on each grid line intersection. One dish contained a container full of Calcium chloride, whilst the other housed distilled H2O. Both dishes were sealed and observed over a period of 3 yearss.A fictile Petri-dish was floated over a pool of H2O in a round glass trough.
Ten inactive snails were placed in the Petri-dish which was left opened, but the glass trough was covered. After one hr, the screen was removed merely plenty to acquire the snails out. These were tapped gently with a glass rod a few times and set back in the trough. The figure of active snails after the intervention was noted.Experiment.3Two indistinguishable Petri dishes as in exp.2 ( with a 4×4 grid ) were prepared with one inactive snail per intersection.
One dish is filled up to about 1mm with sea H2O, whilst the other 1 was left dry. Both dishes were sealed with Vaseline lubricating oil and observed over a period of one hr. This process was repeated merely utilizing fresh H2O alternatively of sea H2O.Snails which had been left in dry air for one hr were tapped aggressively on the shell and instantly placed in 1cm of sea H2O.
The clip taken for the first noticeable motion of the snail ‘s operculum was noted.Experiment.4Two indistinguishable mensurating cylinders were filled with sea H2O one to a deepness of 5cm and the other to a deepness of 20cm. Individual inactive snails were placed in each cylinder, and the clip taken for the snail to travel 5 centimeter up the wall in each container was noted.Experiment.5Two indistinguishable measurement cylinders are filled to a deepness of 3cm with saltwater.
Each cylinder was marked at 3 centimeter intervals get downing from the H2O surface. One cylinder was stoppered tightly whilst the other was left unfastened. The motion of each snail up the cylinder was noted with clip.Experiment.
6Two indistinguishable plastic fish tanks are filled to a deepness of 1.5cm with sea H2O. Regular plastic home bases that were drilled with a form of regular holes were attached to the walls of one of the fish tank. The fish tank were marked away at 3cm intervals get downing from the H2O surface. Ten inactive snails were placed in each fish tank and covered with a palpebra.
After 3 hours the figure of snails at each degree was noted.The process above was so repeated but alternatively of the walls, the drilled home base was placed at the underside of the fish tank. The figure of persons staying submerged was counted at intervals of 1,2,6,24,36… hours.Experiment.7The process of experiment 5 was repeated merely this clip both the cylinders were tightly stoppered and with 10 snails in each one. One of the cylinders is placed in an opaque black bag whilst the other 1 is left in the visible radiation.
The figure of snails at each degree for both cylinders at intervals of 1,3,6 and 24 hours was recorded.PrecautionsSnails that were used for an experiment were non reused but placed individually in a container to observe that they have already undergone some intervention. This was done so as non hold active snails from a old experiment ruin the consequences of the following experiment.The snails were all newly caught ( non more than 2 yearss ) so as to hold an accurate consequence as possible.In most experiments a good figure of persons were used ( like 10 ) and others were possible were replicated.
Adequate clip was left to pass for consequences to be collected as the stimulation that activate the snails may be over a long period of clip.Snails used were chosen to be of similar size ( 0.7cm shell tallness ) and handled really gently.MistakesManaging of snails from gaining control site to lab and from tray to the experiment may hold activated the snails prior to the existent experiment taking topographic point.Most experiments could hold been done merely one time to the long waiting clip, and with a comparatively little figure of persons ( ten snails may non give a representative consequence ) .The experiment tried to retroflex the conditions that the snail would be in the natural state.
This can ne’er be to the full achieved and so the experiment its ego is non so accurate.Motion of setup or activity on the bench could hold changed snail place in other experiments or triping them due to the quiver non to the variable tested.The snails themselves may hold moved other snails in experiment 2 and 3 giving errored consequences.
Time / hourFine sandGravelRough sand0334133423346343242533625348154No snails were noted to hold accumulated on the smooth fictile surface of the Petri-dish.
Time/hrRH=0 %RH=100 %00061230125413
Snails active:Before tappingAfter tapping
Time/hrNumber of snails moved00156122414321548165616
Time for first discernable motion of operculum after left in:Dry conditionsDry conditions followed by tappingImmersed in saltwater14082214833292044331640528920619753783862811451921141310121050
Time/hrNumber of snails moved001060240320480561
Replicate5cm H2O20 cm H2O12340s4140s ( 69 mins )22400s86400s ( 1day )39000s& A ; gt ; 2 twenty-four hours49900s& A ; gt ; 2 twenty-four hours586400s& A ; gt ; 2 twenty-four hours6& A ; gt ; 2 twenty-four hours& A ; gt ; 2 twenty-four hours7& A ; gt ; 2 twenty-four hours& A ; gt ; 2 twenty-four hours8& A ; gt ; 2 twenty-four hours& A ; gt ; 2 twenty-four hours9& A ; gt ; 2 twenty-four hours& A ; gt ; 2 twenty-four hours10& A ; gt ; 2 twenty-four hours& A ; gt ; 2 twenty-four hours
A sum of 2 snails were placed in each mensurating cylinder. The Numberss in the tabular array show the figure of snails recorded at each degree marked.ClosedOpenTime/hr12624324856126243248560-3cm222222222110003-6cm000000000101106-9cm000000000011019-12cm0000000000000012-15cm0000000000001115-18cm0000000000000018-21cm0000000000000021-24cm0000000000000024-27cm0000000000000027-30cm ( top )00000000000000
Part 6AAfter 3 hours:At the underside of the armored combat vehicle ( smooth )In cranniesOn smooth palisadeSubmerged in saltwater8010-3cm above H2O0013-6cm above H2O000
Time/hr12624324856submergedIn crannies6899999On smooth palisade4100001Above saltwaterIn crannies0000000Not in crannies0111110Submerged ( the merely 1 required others are excess )109999910
LightDarkTime/hr12624324856126243248560-3cm1010101010101054444333-6cm000000013100116-9cm000000001222119-12cm0000000200010012-15cm0000000011213315-18cm0000000011000018-21cm0000000000000021-24cm0000000001100024-27cm0000000200111027-30cm ( top )00000000000112
The consequences were organized in the signifier of tabular arraies normally with length in motion or figure of snails against clip.
In the first experiment, habitat penchant was tested. Rough crushed rock and fine/coarse sand are the typical supralittoral substrates and snails may hold a penchant to one and non the other. As observed from the tabular array up to the first few hours, no motion was noted. On the 6th hr a individual snail had changed substrate from the all right sand onto the crushed rock.
At the terminal of the experiment two of the 3 snails placed on the all right sand had moved onto the crushed rock or coarse sand and one from the coarse sand had moved onto the crushed rock every bit good. This indicates that the beings slightly dislike a loose substrate such as the all right sand ( merely 2 remained ) but prefer unsmooth crushed rock ( 5 snails remained ) . The harsh sand was slightly in between the two with 4 snails staying. This is the expected consequence as these beings are found between little stones and in crannies. The fact that non all of the travelled to one substrate could hold been due to the deficiency of infinite as with 5 or 4 snails in one subdivision, the Petri-dish became slightly crowded. No snails were observed to travel onto the smooth Petri-dish surface and this is besides explained by the fact that their home ground penchant is towards bouldery terrain.
In the 2nd experiment, the consequence of humidness on the inactive snails was observed. In portion A which consisted of the two Petri-dishes with the grid, the difference in humidness was created by utilizing Ca chloride ( anhydrous ) . This chemical can absorb the H2O nowadays in the atmosphere making dry conditions whilst the other had a pat with H2O giving the environment 100 % comparative humidness. In the dry dish 6 % of the snails moved whilst in the wet dish, 18 % of the snails moved. Although non so many snails moved the difference from dry to wet is already apparent with approximately 3 times the snails traveling in the 100 % RH than the 0 % RH. This shows that although it is non that strong of a stimulation, the comparative humidness plays a portion in the activation of the canvass.In portion B of experiment figure two, the snails were one time once more exposed to an ambiance of 100 % RH, but they were besides tapped on the shell after one hr and placed back for a few more proceedingss. The tapping seems to hold some consequence on the snails as unlike the 100 % RH in portion A where the snails took yearss to travel, 20 % of the snails in portion B after merely one hr were noticed to be active ( which is approximately the same sum as in portion A at 100 % RH ) .
This suggests that likely the moving ridge action on the snails combined with the high humidness ( as they are wetted ) are effectual stimulations to trip the snails.Experiment 3 consisted of three parts. In the first portion, the Petri-dish had a grid on the underside where 16 snails were placed. In the one which contained the 1mm of sea H2O by the 2nd twenty-four hours all the snails had moved. The period where most snails became active was between the 6th and 24th hr.
This when compared to the old experiment where merely the humidness was at 100 % shows that H2O is a much stronger activator as all the snails moved ( the prohibitionist control had no noticeable motion ) . This would do sense as if there was wave action apart from high humidness and the mechanical force its ego ( both of which have shown positive consequences ) , the snails would most likely become submersed in small pockets of sea H2O. Interesting to observe that when as in portion 3C the H2O used was fresh H2O, no snails moved up to 24 hours and merely one moved merely somewhat over the 3 yearss period ( likely due to humidness non the H2O its ego ) .
This is interesting to observe. It can likely be explained by the fact that if it were to rain over the snails which in August or September ( although rare ) it might, although the snail would experience the mechanical force, be in an ambiance of high humidness and covered in H2O it would non be good to come out of quiescence as the environment would non yet be suited and so it must be sea H2O to trip the snail as this would merely come ashore from moving ridges ( bespeaking a suited environment ) . In portion B of experiment 3 the clip taken for each snail to go active was noted.
Prior to the experiment, they were aggressively tapped. This tapping followed by the submergence in sea H2O immediately brought about a response from the snail which opened its operculum. This was really fast, in fact an mean clip of 17.5 seconds was recorded between the 10 snails tested.
This one time once more replicated moving ridge action merely a faster response was obtained due to the fact that existent sea H2O was used and non high humidness or tapping merely ( which continues to propose that the snail becomes active after summer during the winter storms ) .
Up boulder clay experiment 3, sea H2O was known to convey about a response, the inquiry so was ( answered by experiment 4 ) if more H2O would convey about a faster reaction. Apparently this is non so as the clip taken for the snails to go a distance of 5cm up the wall of the cylinder incorporating 5cm of H2O was less than the cylinder incorporating 20cm of sea H2O. This can likely be explained by the fact that the snail is non adapted to populate in deep H2O but it is really semi-terrestrial merely embarking into the sea to put its eggs. Thus a higher hydrostatic force per unit area of 20cm would bespeak an unsuitable environment and the snail will most likely remain hibernating.
Therefore lone frequent wetting and non submersing ( in more than 10cm of H2O ) brings about a response ( one time once more pools brought approximately by moving ridges are normally non every bit deep as 20cm in little crannies where the snail sums ) .
Experiment 5 was slightly elusive and likely should non be considered as a representative consequence. Merely a few snails were activated and the snails which travelled most up the cylinder were in the one non stoppered! An expected consequence based on the other old experiments and cognition of the snail ‘s habitat penchant would be something as follows. Upon presenting the snails to the 3cm of saltwater, they would go active and since they would be submerged happen a manner out which would be to mount onto the cylinder ‘s side. Since their home ground lies a just distance from the sea, the snail should go on to mount up to a good few centimeters.
The snails in the stoppered cylinder should make the top as the high humidness indicates that they are still really near to the H2O and travel up every bit far a possible. In the unfastened cylinder holding a drier atmosphere, the snails would likely non travel up to the top as they would be under the ‘impression ‘ that they are a just adequate distance from the ‘sea ‘ located at the underside.Experiment 6 was an extension of experiment 5 where the upward motion from a submersed topographic point was tested merely this clip the variable was non humidity but terrain brought approximately by the drilled home bases stuck to the sides of the armored combat vehicle. Again the information was non as expected so much so that the somewhat different version experiment portion 6B did non hold the same consequences as A but was as expected. The grounds for experiments 5 and 6A being slightly non accurate could be due to the mistakes mentioned in the beginnings of mistakes subdivision above. If one were to follow the consequence brought about by experiment 6A it would be concluded that the snails prefer to stay submersed and on smooth surfaces instead than in the crannies. This of class is non the instance as the snails prefer crannies in stones as seen from experiment 1 and besides in the wild these are found in crannies non submerged on smooth surfaces.
In portion B where the drilled home base was placed at the underside, the snails aggregated in the cavities and stayed submerged. This would bespeak that they really do prefer crannies and cavities which offer protection against the elements. The cavities were submerged, but the expected consequence was that despite this the snails should non travel out of the H2O. This is because they were submerged under merely 1.5cm and in the natural state this would be something common for a snail in a little cavity to see a few millimeter of sea H2O. So in the cavities and under H2O the mollusk is really in its preferable environment.
Finally experiment 7 tested if the snail is light-sensitive. Harmonizing to the consequences obtained, when in visible radiation the snails ( all 10 of them ) became active faster ( in the first hr even ) and climbed a distance of 3cm, whilst in the covered cylinder half as much became active and over a longer clip period. The unusual thing was that in the visible radiation, the snails did non make the top and in the dark merely 1 did.
Sing the high humidness in both, all the snails should hold gone up to the top, the lone difference ( if there is ) would be in the clip taken.Taking into consideration all the consequences obtained and sing the concordant informations, it is noted that the snails become active via assorted stimulations. In summer humidness is low and the snail would be in a cranny seeking safety from the direct Sun. When the first storms come along, the cranny the snail would be in becomes wet with sea H2O and really humid ( a kind of micro home ground ) . The thumping action of the moving ridges besides has an consequence on the snail.
The mollusk is at place under a few centimeters of H2O and in fact in November to March during high tide the snail travels from its home ground to the Eulittoral zone ( which is covered in H2O during this period of the twelvemonth ) and lays its eggs. The snail is affected by hydrostatic force per unit area ( experiment 4 ) and so merely travels a specific distance into the sea ( which would be the optimal topographic point to put its eggs ) . It besides detects the comparative humidness and merely ventures up shore a fixed distance ( up to the supralittoral zone ) from the sea. In this zone lichens besides turn in the winter and spring times. These are a premier beginning of nutrient for the snail and may be another ground why it aestivates as in summer, this nutrient beginning dries up.
Having done the experiments and observed the consequences, it can be concluded that there are assorted factors which play a portion in triping the snail. Each factor affects the snail to a certain grade and the combination of all of them ( humidness, mechanic moving ridge action, sea H2O etc ) brings about a reaction either to be inactive due to their deficiency or to be activated due to their presence.