Post on 27-Nov-2014
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Rizal Technological University Boni Ave. Mandaluyong City
College of Arts and SciencesDepartment of Biologymajor in Biotechnology
In partial fulfillment of the Requirementsin Animal Cell Physiology and in vitro Culture
Behavioral Physiology of Hermit Crabs in Different Water Conditions
Submitted by:
Justine M. AlmanonJowanna Marie L. Burce
Romnick J. FeraldoJuaymah B. Policarpio
Submitted to:
Prof. Angelita P. Medalla
11th October , 2010
Introduction
Hermit Crab, common name for any member of a family of marine crabs
and for several related terrestrial crabs. They are found on or just off the coasts
of Europe and the Americas. Hermit crabs, also called robber crabs, are
armorless animals, the largest of which are found along the Pacific coast and
attain a length of up to 46 cm (18 in). They insert their abdomens into gastropod
mollusk shells that they carry about with them for protection. The abdomens of
the crabs are soft and asymmetrical, flexed and twisted to fit into the whorls of
the borrowed shells. Their abdominal appendages are especially modified for
keeping the shell firmly supported on the body (Redmond, WA: Microsoft
Corporation, 2008)
According to Hazlett (1996) hermit crabs are often forced to seek new
shells because they have outgrown their old ones; they change their housing
whenever chancing upon another shell into which they can fit. Most hermit crabs
are marine. The few terrestrial forms are tropical and of the same family as the
coconut crab. Tricarico & Gherardi (2007) stated that Hermit crabs are ideal
organisms to investigate whether resource assessment might effectively modify
an animal’s motivation and to what extent. The survival, growth, and reproduction
of this taxon strictly depend on the occupancy of gastropod shells of appropriate
size and shape. A shell that is, for instance, too small can inhibit the growth of
the inhabiting crabs, reduces their protection against predators and their survival,
and affects reproductive success in both sexes. By contrast, a shell that is too
large makes locomotion energetically wasteful (as found in terrestrial hermit
crabs, and affects female reproduction. Shell fit may also alter hermit crabs’
responses to environmental cues and their general behavior. Therefore, there is
a strong selective pressure for hermit crabs to obtain a shell of the appropriate
size.
Hermit crabs display clustering behavior and daily movements which are
closely related to the tidal rhythm (Turra & Leite, 2000). Clusters are typically
formed during low tides when hermit crabs stay in physical contact with each
other, presenting low activity and preference for shady substrates. The clustering
behavior is probably controlled by interaction between exogenous and
endogenous factors related to the tidal cycle. In this way, environmental stimuli
(air exposure, hydrostatic pressure, light, food availability and small scale water
movements) seem to play an important role in the determining the activity of the
hermit crabs.
The main objective of the study is to determine the effects of different
water conditions in the behavior physiology of Hermit Crabs. To modify their
behavior in appropriate manner and to observed their switching shells if an empty
shell is available.
Review of Related Literature
Cenobita spp., commonly known as Hermit Crab, unlike true crabs have
soft, vulnerable abdomen. In order to protect their soft bodies from predators,
hermit crabs use abandoned shells of other marine animals, mostly snails. Once
it has outgrown its shell, it discards it and looks for a new shell. This behavior of
the hermit crab gives rise to competition for shells among the members of this
species (Bose, 2010). As the distribution of hermit crabs is very wide, the have
been able to adapt to several different kinds of habitats. Though they are usually
found in shallow waters, some hermit crabs even live in plant stems, while
several species are found in kelp forests. Possibly the best know hermit crabs
facts is that their bodies do not have a hard, protective carapace. They need a
shell to protect then from predators, which is why they use discarded snail shells
or other hollow objects. They move around by dragging their shell with them, and
retreat into it when threatened (K, 2010).
There are almost 500 different species of the hermit crab. Some are
aquatic whereas there are others that are terrestrial. The hermit crab habitat of
the aquatic forms range from the shallow waters of the coral reefs and shores to
the depths of the bottom of the sea. The best places to look for hermit crabs are
the inter-tidal areas, for example the tide pools where a large number of
planktons can be found. The terrestrial forms are usually found in the tropics.
There is also the Caribbean hermit crab that is known to be capable of climbing
up trees (Bose, 2010). Among the 500 listed species of Hermit crabs,
approximately only 15 species are terrestrial, while the rests are aquatic. Most of
the species of Hermit crabs popular as pets are terrestrial in nature. These
include prominent species such as the Caribbean hermit crab, Australian land
hermit crab and the Ecuadorian hermit crab. Other than these species, a few
more species are becoming popular due to their longer life span and availability
in abundance. The average life span of the species kept as pets initially, seldom
exceeded a few months. More recently, it has been observed that some species
of Hermit crabs tend to live for relatively longer period, if proper care is provided.
In fact, species like the Caribbean hermit crab have an average life span of 23
years; with some individuals even living for 30 years or more, though such
examples are rare (Naik, 2010).
The most general classification is the Kingdom Animalia, which contains
all the animals on Earth. Hermit Crabs belong to one of the largest groups of
animals. The arthropods known as Phylum Arthropoda. They are invertebrates
that have jointed legs and a hard outer covering called exoskeleton. The Phylum
Arthropoda is further broken down and includes the Class Crustacea. It is divided
into Order such as crab, lobster, and shrimp which are all in the Order Decapoda.
(Choosing Crustaceans: All about Hermit crabs (n.d.) Moreover, Hermit crabs
can’t reproduce in captivity as they do in the wild. When mating, the Hermit
Crabs extended about ¾ of the way out of their shells. The male uses his flexible
fifth pair of legs to place his spermatophore into the female’s gonophores. After
the crabs have mated, the female attaches the eggs to her abdomen inside her
shell and carries them around with her until they are ready to hatch. Hermit crab
eggs must be hatched in salt water in order to survive. They use the tiny pinchers
on the end of her fifth pair of legs to snip each cluster of eggs from her body. The
eggs hatch upon contact with the sea water and the little creatures are released.
Hermit crabs are one of the most extraordinary pets because of their
ability to make attention-grabbing, easy care friends. They have very distinctive
characteristics; have vigorous and inquisitive nature, and their unique personality
with low maintenance charges make them appealing to us as good pets as long
as we provide them proper environment and food. Basically, Hermit Crabs are
omnivores, which mean they feed on both vegetation and animal material. There
are two types of Hermit Crabs found, marine and land hermit crabs. Usually,
Land Hermit Crabs are considered as good pets (Pakhare, 2010). Their feeding
behavior is highly fascinating retreat for eyes. In the wild, land hermit crabs eat
almost anything like fallen fruit, leaf litter, decaying wood, plants and grasses.
Although they are not specific in their diet, recent studies have shown that hermit
crabs need calcium, carotene and antioxidants (McGuigan, 2010). It can witness
the fading in their color at the time of molting if their diet is carotene deficient. It
can supplement their diet with brightly-colored vegetables, like corn and carrots
to make up the deficiency of carotene. It can feed them meat, fish, vegetables
and fruit as they are omnivorous in nature. They also like tannin-rich foods like
tree bark and oak leaves. (Pakhare, 2010). Hermit crabs are nocturnal
scavengers that will eat almost anything. Based on the article of Land Hermit
Crabs (2002), they are terrestrial crabs that carry their shells on their backs. And
like the other crabs; they are decapod (ten-legged) crustaceans. In addition,
Choosing Crustaceans: All about Hermit crabs (n.d.) states that hermit crabs
have long abdomen that curl under their bodies. They also use only three pairs of
legs for walking and have longer antennae than the true crabs. In the same way,
hermit crabs are actually quite sociable creatures. In the wild, they live in
colonies and often travel in packs of up to 100 crabs. Fight occasionally breaks
out among these crabs as they outgrow their shells and look for larger ones to
inhabit.
During the day, hermit crabs conceal themselves from the harsh sun and
predators by hiding out under trees, driftwood, leaves, and rocks or by burying
themselves in the sand. But during the cooler evening hours, they wonder the
beach looking for food, searching for new shells, and mating. However, they are
very particular about their shells, which offer them much needed protection in the
wild. The crabs always seem to be looking for newer, bigger or better shell to
move in.
Molting is a process in which a hermit crab faces a lot of stress so it is at
this time that it requires a lot of care and concern. Molting is a natural process of
growing for a hermit crab wherein it sheds its exoskeleton and forms a new one.
The frequency at which a crab molts depends on the growth rate and size of
individual crabs with smaller ones molting every 3 to 4 months and larger ones
molting once every year. This is a time that the hermit crab needs to be treated
with extra care as it is defenseless and vulnerable (Gupta, 2010).
Male hermits are often seen dragging around a female by their small claw,
fiercely fighting off rival suitors with their big claw. The male will drag his potential
mate around until she is ready to molt. When the female crab molts she is
receptive and the male can then fertilize her eggs. Hermit crabs are mainly
scavengers and can often be seen digging for food, preying on smaller
organisms, or scrounging for scraps on the ocean floor (Ellie, 2010).
Hermit crabs are common in tropical intertidal areas of the world and
occupy the empty shells of marine gastropods. However, unlike the original
gastropod owner of the shell, they are unable to completely seal off the aperture
of the shell in times of environmental stress, such as dilution of seawater by fresh
water. These factors may make hermit crabs better indicators of changes
occurring in intertidal conditions and community structures than snails, clams and
oysters which can temporarily seal out unfavorable changes in surrounding
conditions. Further, hermit crabs, like many other decapods, tend to have a
limited capacity for osmotic regulation. Consequently, they are vulnerable to
osmotic stress caused by freshwater inundation resulting in the dilution of sea
water. Species, however, may differ in their tolerance to dilution of their blood
and body fluids, and therefore, in their survival during episodes of freshwater
inundation (Dunbar et al., 2003).
The cognitive abilities of hermit crabs in information gathering and
decision making are impressive. They rely on the use of gastropod shells for
shelter and shells of adequate size, shape and strength, but without being too
heavy, are key resources. A hermit crab gathers information about shells by
vision (Reese 1963) but this information is enhanced during approach and
contact. After contact it grasps the shell with its walking legs and chelipeds and
explores the exterior, moving its chelipeds over the surface, and then turns the
shell so that the aperture is uppermost and begins to investigate the interior by
inserting one or both chelipeds or sometimes a walking leg. It obtains detailed
information as to the size, internal volume, shell species (shape) and weight
during this process and assesses the overall quality relative to that of the shell it
is currently occupying. The crab may move into the new shell and test the inside
of the shell by thrusting the abdomen back and forth. It might also investigate the
interior and exterior of the original shell and even move back into it, assessing
which is the better of the two. Hence these crabs demonstrate sophisticated shell
investigation behavior, remembering the information gathered at each stage of
the investigation, and also remembering specific shells for up to 40. They may
also fight another crab over ownership of shells in which case information about
the shells and the opponent is integrated with information about their own
physiological state. They can remember previous opponents for up to 4 days and
it has been suggested that they may select which crabs to fight on the basis of
their perception of how their current shell might suit the opponent. Thus crabs
have the ability to gather and use information from a variety of sources and to
make comparisons between shells and between opponents (Elwood & Appel,
2009).
Many invertebrates do appear able to assess risk levels based on
chemical stimuli. For example, marine snails can distinguish between predatory
and non predatory brachyuran crabs, starfish and snails as well as between
crabs fed conspecific or other snail species. Freshwater snails respond differently
to the scent of different predators (fish or crayfish) fed conspecific snails.
Barnacles can distinguishbetween predatory and nonpredatory snails and
starfish. Mussels can distinguish between predatory crabs and herbivorous
urchins, and burrowing bivalves can distinguish between feeding and starved
crabs. Similarly, snails, polychaete worms and crabs can all distinguish chemical
stimuli released by damaged conspecifics from those released by more distantly
related prey. Hermit crabs respond differently to different chemical stimuli in their
environment. They can distinguish their own scent from that of other individuals.
Predator effluent may interfere with mating, and odors from living, damaged or
dead snails or conspecific hermit crabs attract them or increases shell grasping
behaviour. Hermit crabs also respond to visual stimuli in their environment, and
these responses may be modulated by olfactory cues. Shell-breaking crabs are
important predators of hermit crabs. Although hermit crabs clearly respond to the
effluent from predatory crabs, whether they can distinguish between predatory
and non predatory crabs remains unclear (Rosen et al., 2009).
Hermit crabs are ideal organisms to investigate whether resource
assessment might effectively modify an animal’s motivation and to what extent.
The survival, growth, and reproduction of this taxon strictly depend on the
occupancy of gastropod shells of appropriate size and shape. A shell that is, for
instance, too small can inhibit the growth of the inhabiting crabs, reduces their
protection against predators (e.g., Angel 2000) and their survival, and affects
reproductive success in both sexes. By contrast, a shell that is too large makes
locomotion energetically wasteful and affects female reproduction. Shell fit may
also alter hermit crabs’ responses to environmental cues and their general
behavior. Therefore, there is a strong selective pressure for hermit crabs to
obtain a shell of the appropriate size. Empty shells (hermit crabs are unable to
directly prey on living snails; for an exception, are in acutely short supply in the
habitat. Most often, they can be found after snail death at gastropod predation
sites. Alternatively, shells may be obtained by conspecifics or heterospecifics
through negotiation or interference competition. In any case, except for very few
instances, appropriate shells are extremely difficult to recruit. As a result, the vast
majority of the hermit crab populations studied so far chronically suffers from a
reduced growth. An apparently obvious consequence of the vital importance of
empty shells for hermit crabs on the one hand, and of their scarce availability on
the other, is that these organisms have evolved the ability to make fine
distinctions between the quality of a shell found in the habitat, either empty or
occupied by conspecifics or heterospecifics, and the current domicile shell. This
ability has been confirmed by a large number of studies, mostly conducted in
Pagurus bernhardus. For instance, escalated shell fights occur in this species
when the shell at stake is of a higher quality than the attacker’s domicile shell.
Similarly, individuals enter an empty shell more quickly when there can be an
increase in quality, whereas the speed of rejecting the shell correlates with its
unsuitability. Knowledge about the quality of an external shell is obtained by
hermit crabs first by the means of sight and later by tactile stimuli acquired during
their manipulation of both the exterior and the interior of the shell–shell
investigation (Tricarico & Gherardi, 2007).
The cognitive abilities of hermit crabs in information gathering and
decision making are impressive. They rely on the use of gastropod shells for
shelter and shells of adequate size, shape and strength, but without being too
heavy, area key resource. A hermit crab gathers information about shells by
vision but this information is enhanced during approach and contact. After
contact it grasps the shell with its walking legs and chelipeds and explores the
exterior, moving its chelipeds over the surface, and then turns the shell so that
the aperture is uppermost and begins to investigate the interior by inserting one
or both chelipeds or sometimes a walking leg. It obtains detailed information as
to the size, internal volume, shell species (shape) and weight during this process
and assesses the overall quality relative to that of the shell it is currently
occupying (Elwood & Appel, 2009).
Materials and Methods
Collection of Hermit Crabs
Cenobita clypeatus were collected from Cartimar in Gil puyat Avenue,
Makati Extension, Pasay City. They were separated randomly into three groups
with three samples each that were submerged with different water condition.
Hermit crab were gathered immediately transported to the laboratory where they
were be kept in aquariums for 12 hours light and acclimated in a constant
temperature at 25-27°C in aerated water for at least two weeks before being
exposed to treatments.
Preparation of Water in Different Conditions
In order to assess the different conditions, capabilities and how it would be
affected by water types, the hermit crab were submitted to individual and
combined saltwater and Artesian well water taken in Pateros. Using groups of
three Hermit Crabs submerged in water with different conditions have been
tested: (1) Artesian well water (groundwater, GW); (2) Saltwater (SW); (3)
Artesian well water + Saltwater (GW+SW), and (4) Control (aerated water).
Setting of the Experimental Conditions
Cenobita clypeatus were weighed every week, until the 21 days of
exposure have been completed. They have been selected for testing without
regard to the shell type, weight, and no effort was made to mate the individuals.
For setting-up the videos, these were created by filming the natural environment
of the hermit crabs. Using 30 cm wide colored video monitor was placed outside
of the aquariums. The duration of filming were recorded every Friday between
September 17, 24, and October 1, 2010. Extraneous sound, vibration and visual
stimulation were minimized during the experiment and all the filming were
conducted between one to three hours.
Survival Test
In laboratory, hermit crabs were kept in three glass aquarium with the
volume of two liters of saltwater for Aquarium (SW), two liters of Artesian well
water for (FW), 1 liter for (SW) + 1 liter of FW for SW+FW aquarium and for the
control, Aerated water (AW) was used. The crabs were fed thrice a week with
tiny shrimp pellets, etc.
Experiments investigated the survival of Cenobita clypeatus to different
water conditions at different pH. Twelve individuals of hermit crabs were
randomly selected and three individuals placed in aquariums with different
conditions. Throughout the duration of experiment, Hermit crabs were observed
for signs of life. Individuals that did not respond by the movements of antennules,
walking legs, chelipeds and with foul odor, were considered dead and are to be
removed from the aquarium. The interval in which each hermit crab died was
recorded.
Behavioral Physiology
The behavior of the Hermit crabs was observed for a total of 5 hours. Two
separate behaviors were observed and these occurred to varying degrees
depending on the water conditions:
Locomotion of Hermit Crab
The locomotion was examined in the laboratory. This was the only
behavior that has been described previously in relation to water conditions.
According to McGaw et. al, (1999), locomotion activity were quantified each time
the hermit crab changed the speed whether it is fast, slow or moderate as they
submerged in water. Hermit crabs have two types of pattern in terms of
movement which Herreid & Full (1986) observed. It can be move forward and
sideways.
Flicking of antennae
The antennae were flicked up and down, independently of each other;
each separated movement was counted as an event. To determine the
percentage time of antennules retraction, we observed the antennules made
continuous rapid flicking movement while extended, but for periods of time they
would be folded backwards into a depression in the carapace; the approximate
percentage of time and the antennules were retracted was observed (McGaw et
al, 1999).
Shell Acquisition
Using the empty shell, we were offered the hermit crabs empty shells and
observed the movement of their resource, the empty shell or vacancy, a chain of
interactive events.
Three Hermit crabs for each sample were randomly assigned three empty
shells for observation the movement of their resources, the empty shell or
vacancy, in a chain of interactive event. For each of them, it recoded the
likelihood and total duration of shell investigation.
Hiding Times
To determine the hiding times of hermit crabs: the time elapsed from the
moment of the tap until the hermit crab emerged fully from its shell, was recorded
to the nearest second with a digital stopwatch.
Results and Discussion
Survival test
Exposure of the crabs to both SW + GW resulted in important increased of
10% of the total body weight after 10 days. No change in weight was observed
upon exposure to saltwater and aerated water. Exposure of the crabs to GW
resulted in mortality: 1 hermit crab died (within 15days).
Table 1 shows the survival rates of the hermit crabs in SW, SW + GW and
AW in low pH. From this table, it can be clearly seen that hermit crab survive
notably in SW, better than GW in 7 pH. Survival of hermit crabs for all water
conditions are the longest at the acclimation of room temperature. In controls
(AW), 3 hermit crabs had 100% survival after 21 days of exposure, respectively.
In SW and SW + GW, all hermit crabs are still alive while in GW, one hermit crab
died. However, Hermit crabs in SW and SW + GW survived extensively rather
than GW which has two crabs survived after 15 days of exposure.
Alive Total Dead Total
SW GW SW+GW AW SW GW SW+GW AW
September17 3 3 3 3 12 ---- ------ ---------- ---- 0
September24 3 2 3 3 11 ---- ------ ---------- ---- 1
October 6 3 2 3 3 11 ---- ------ ----------- ----- 0
Table 1 shows the survival rates of Hermit crabs in Different Water Conditions.
Laboratory studies indicated a higher tolerance of Cenobita sp. in SW
longest periods of exposure. Prolonged exposure to low pH in the experimental
condition resulted in a significant differences in survival in favor of Cenobita spp.
Shell acquisition
Hermit crabs rely on shell for their survival. A total of ten observations
were made resulted in 6 fights. This observation was analyzed because the
hermit crab initiated shell fight. Fights were most possible observed in GW and
least possible in SW. In the first week of experimental conditions, we observed
that 1 of the hermit crabs in SW + GW aquarium has a missing limb. Gupta
stated that once the hermit crab loss limb, they begin to restore their limbs by
growing a gel limb. This is a natural process called molting wherein hermit crab
shed its exoskeleton and forms a new one. According to Childress, it is a time
where hermit crab needs to have a new empty shell to fit in. in fact, empty shells
are extremely rare in some environment, all except the most damaged being
occupied by the crabs. As a result of the limited nature of useful gastropods shell,
there is competition associated with highly ritualized aggressive display and shell
fighting behavior. In addition, reduced hiding time when attacked by a shell
breaking crab is probably adaptive because it would abandoned their shell and
flee when picked up by a large, shell breaking crab.
Behavioral physiology
Locomotor activity
Hermit crab usually moves forward rather than sideways. Locomotors of
Cenobita spp. Increased as the pH decreased. In SW, there was a large variation
between individual crabs. Although there was a strong movement towards
greater activity in low ph. Locomotion of hermit crabs was move to manifest in
SW + GW aquarium wherein activities remained important above conditions in
the duration of the experiment. Both SW and GW showed an immediate
increased in activities of the crabs as the pH lowered. However, the pattern was
somewhat differ in AW and SW + GW. The activity level of Hermit crab in GW
decreased during the 2 hours of exposure and in AW was largely inactive after
30 minutes. They covered themselves in the sand and rocks, and move from
time to time. We also minimized the used of driftwoods to avoid overstay in
branches for them to submerged in different water conditions. Mortality was low
after 3 weeks of exposure and the acclimation time used would be a good
adjustment that are made by hermit crabs to specific set of laboratory
conditions .Cenobita spp. Walk forward on six legged using an alternating tripod
gait similar to that of insects. The first walking leg provides the driving force for
locomotion aided secondarily by the second walking leg, while the cheliped act
largely as support. The left appendages are longer and heavier that the right and
they extended further laterally from the midline during their stride, thus
compensating for the asymmetry of the crab which has dextrally coiled shell and
abdomen displaced to the right. The abdomen is normally carried off the ground,
but it is dragged when the shell is large. This has been confirmed by other
studies (Herreid II & Full, 1986).
Flicking of Antennae
The antennae and antennules of crustaceans have been implicated as
having a chemo sensory role in water exposure (Mcgan et al., 1999). Both the
antennae and antennules were flicked up and down during the experiments.
Each Hermit crab also responded to a decrease in pH with an increase in
frequency of flicking their antennae. In saltwater, the HC antennae were flicked
up and down, on the average, 2-3 times per minutes, and it did not change with
the water condition. There was also no significant change in antennae flicking in
AW, since this behavior was only observed in GW and SW aquarium.
The antennules of all the crabs were flicked rapidly while oriented in
different directions, but were also retracted into the carapace for period of time.
In GW, each species retracted the antennae for about S-20 second of every
minute, but distinct differences between the species occurred in the lower pH.
Crabs in AW retracted its antennules upon initial exposure, but after 10 minutes
the antennules remained extended. For the entire experimental condition, the
pattern was similar in SW + GW, with the antennules exposed for longer periods
in all. In SW and GW, the opposite response was seen, in low pH, the HC
retracted the antennules. Each HC individuals in GW also retracted the
antennules to a greater degree in all experimental condition, but there was no
significant differences in the retraction times between the GW, SW, AW and SW
+ GW, as occurred in HC. However, with such variability within and between the
species, it is hard to draw conclusions as to the role of the antennae in salinity
detection (Mcgan et al.,1999). The percentage of time that the antennules were
folded dack into the carapace was recorded because flicking was too rapid to
allow accurate determinator of rate. According to Van Weel et at., possibly these
HC avoid low pH exposure with an isolation type response. These results as well
as other behavioral and physiological work suggest that the antennules are more
important than the antennae for salinity setection. In addition to the antennae and
antennules HC posses’ hair –peg organ on many areas.
Hiding time
Log transformation normalized the distribution of hiding times and also
homogenized the variances. Mean hiding times varied by a factor of two among
the experimental condition and those differences are highly significant. Hiding
time (time to emerge from the shell after disturbance) is a convenient behavior of
hermit crabs because it is easy to score quantitatively (Rosen et al.,2009) and it
is a useful measure of response to predation risks. Hiding times of hermit crabs
might increase either in the presence of predators that are unlikely to break
through their gastropod-shell retreat, or in the presence of visually orienting
predators that are on prey motion (Hazlett, 1997)
Conceptual Framework
Preparation of Hermit Crabs
List of Figures
Preparation of Water in Different Condition
Setting of the Experimental Condition
Survival Test
Behavioral Physiology Observation
Locomotion of Hermit Crabs
Flicking of Antennae
Shell Acquisition Hiding times
Figure 1. Acclimation of aquarium, a) Aerated Water, b) Groundwater, c)
Saltwater and d) Saltwater + Groundwater.
Figure 2. Selection of Hermit Crabs in different water condition, a) Aerated
water, b) Groundwater, c) Saltwater and d) Groundwater + Saltwater.
Figure 3. Preparation of artificial environment in different water condition
References:
Briffa, M., Elwood, R., &, Dick, J. (1998). Analysis of repeated signals during shell fights in the hermit crab Pagurus bernhardus. The Royal Society, 265, 1467-1474. Retrieved July 30, 2010 from http://www.ncbi.nlm. nih.gov/pmc/articles/PMC1689224/
Bose, D. (2010). Hermit crab habitat. Buzzle.com. Retrieved August 23, 2010 from http://www.buzzle.com/articles/hermit-crab-habitat.html
Dunbar, S., G., Coates, M., &, Kay, A. (2003). Marine hermit crabs as indicators of freshwater inundation on tropical shores. Memoirs of Museum Victoria 60 (1), 27-34. Retrieved September 1, 2010 from http://resweb.llu.edu/ sdunbar/pdf_files/DunbarCoatesKay2003.pdf
Ellie, (2010). The hermit crab. Ocean Link-all about the ocean. Retrieved August 23, 2010 from http://www.oceanlink.info/biodiversity/hermitcrab/ hermitcrab.html
Elwood, R., &. Appel, M. (2009). Pain experience in hermit crabs? Journal of Animal Behavior, 77. Retrieved September 1, 2010 from www.elsevier.com/locate/yanbe
Gupta, R. (2010). Hermit crabs: care for molting. Buzzle.com. Retrieved August 23, 2010 from http://www.buzzle.com/articles/hermit-crab-habitat.html
Hazlett, B. (1971). Chemical and chemotactic stimulation of feeding behavior in the hermit crab Petrochirus Diogenes. Comparative Biochemistry Physiology, 39, 665-670. Retrieved September 9, 2010 from http://deepblue.lib.umich.edu/handle/2027.42/33600
Hazlett, B. (1996). Comparative study of hermit crab responses to shell-related chemical clues. Journal of Chemical Ecology, 22 (12), 2317-2328. Retrieved September 9, 2010 from http://deepblue.lib. umich.edu/handle/2027.42/44892
Hermit Crab. Microsoft® Student 2009 [DVD]. Redmond, WA: MicrosoftCorporation, 2008
Herreid, C., &, Full, R. (1986). Energetics of hermit crabs during locomotion: the cost of carrying a shell. Journal of Experimental Biology, 120, 297-308. Retrieved September 9, 2010 from http://jeb.biologists.org/ cgi/content/abstract/120/1/297
K, M. (2010). Fun facts about hermit crabs. Buzzle.com. Retrieved August 23, 2010 from http://www.buzzle.com/articles/hermit-crabs-facts.html
McGaw, I., Reiber, C., &, Guadagnoli, A. (1999). Behavioral physiology of four crab specie in low sanity. Biological Science Bulletin, 196, 163-176. Retrieved August 29, 2010 from http://www.biobull.org/cgi/reprint/1962.pdf
McGuigan, B. What do hermit crabs eat? The Slobber Blotter. Retrieved August 23, 2010 from http://www.wisegeek.com/what-do-hermit-crabs-eat.htm
Morris, S., &, Van Aardt, W. Salt and water relations, and nitrogen excretion, in the amphibious african freshwater crab potamonautes warreni in water and in air. The Journal of Experimental Biology 201, 883–893 August 12, 2010 from http://www.jeb.biologist.org/reprint/210/6/883.pdf
Naik, A. (2010). Hermit crabs as pets. Buzzle.com. Retrieved August 23, 2010 from http://www.buzzle.com/articles/hermit-crabs-as-pets.html
Pakhare, J. (2010).Pet hermit crabs-hermit crab care. Buzzle.com. Retrieved August 23, 2010 from http://www.buzzle.com/articles/hermit-crabs-care-for-molting.html
Rosen, E., Schwarz, B., &, Palmer, R. (2009). Smelling the difference: hermit crab responses to predatory and non predatory. Journal of Animal Behavior, 78, 691-695. Retrieved September 1, 2010 from www.elsevier.com/locate/yanbe
Small, M., &, Thacker, R. (1994). Land hermit crabs use odors of dead conspecifics to locate shells. Journal of Experimental Marine Biology and Ecology, 182, 169-182. Retrieved August 19, 2010 from http://deepblue .lib.umich.edu/handle/2027.42/31261
Torres, G., Anger, K.. &, Gimenez, L. (2006). Effects of reduced salinities on metamorphosis of a freshwater-tolerant sesame seed crab, Armases roberti; Is upstream migration in the megalopa stage constrained by increasing osmotic stress? Journal of Experimental Marine Biology and Ecology, 338, 134-139. Retrieved August 20, 2010 from http://eurekamag.com/research/012/021/
Tricario, E., &, Gherardi, F. (2007). Resource assessment in hermit crabs:the worth of their own shell. Journal of Behavioral Ecology. Retrieved September 1, 2010 from http://beheco.oxfordjournals.org/content/early/ 2007/03/26/beheco.arm019.full.pdf
Turra, A., &, Leite, F. (2000). Clustering behavior of hermit crabs (Decapoda anomura) in an intertidal rocky shore at Sao Sebastiao, southeast Brazil. Journal of Brazilian Biology, 60 (1), 39-44. Retrieved September 9, 2010 from http://www.ncbi.nlm.nih.gov/pubmed/10838922
Veltman, T. (2010). Introducing the hermit crab. NORTH. Retrieved August 23, 2010 from http://www.xs4all.nl/~pal/hermit.htm
Williams, J. (2005). The not so lonely lives of hermit crabs: studies on hermit crab symbionts. Department of Biology. Retrieved August 30, 2010 from http://ebookpedia.net/The-Not-So-Lonely-Lives-of-Hermit-Crabs--Studies-on-Hermit-Crab----.html