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At least 343 records · Page 19Linked to original sources
PubMed1997

Urate deposits in the gecarcinid land crab Gecarcoidea natalis are synthesised de novo from excess dietary nitrogen

The urate content of the gecarcinid land crab Gecarcoidea natalis was correlated to the amount of nitrogen assimilated. Crabs fed a high-nitrogen diet (ad libitum amounts of soy beans and fig leaves, Ficus macrophylla) for 6 weeks assimilated approximately 23 times more nitrogen (33.9±5.6mmolkg-1day-1) than animals fed a diet low in nitrogen (fig leaves alone) (1.5±0.7mmolkg-1day-1). Animals maintained on a high-nitrogen diet accumulated urate (67.1±29.4mmolkg-1drymass), while animals fed the low-nitrogen diet did not accumulate significant amounts of urate compared with the control animals killed at the beginning of the dietary period. The urate deposits clearly originate from the excess dietary nitrogen ingested on the high-nitrogen diet. The intake of preformed dietary purine was low (0.028±0.005mmolkg-1drymass) and at most could only account for 0.04% of the urate accumulated by crabs fed the high-nitrogen diet. This indicates that the urate was synthesised de novo. When crabs were fed a high-nitrogen diet supplemented with [15N]glycine, the 15N heavy isotope was incorporated into urate. This provided direct evidence that the urate was synthesised de novo.

Journal Article↗
PubMed1997

Digging in sand crabs (Decapoda, Anomura, Hippoidea): interleg coordination

Sand crabs (Decapoda, Anomura, Hippoidea) are highly specialised for digging into sand using their thoracic legs. Using video-recording and electromyography, we examined the digging leg movements of three species of sand crabs belonging to two families: Blepharipoda occidentalis (Albuneidae), Lepidopa californica (Albuneidae) and Emerita analoga (Hippidae). The digging patterns of all three species are similar. The ipsilateral legs 2 and 3 are tightly coupled and shovel sand forward from underneath the animal, whereas the movements of leg 4 are more variable, apparently stirring up sand and providing the purchase for rearward descent into the sand. The digging patterns of B. occidentalis and L. californica resemble each other more than either resembles that of E. analoga. In the albuneids, leg 4 cycles at the same frequency as legs 2 and 3, and both albuneid species switch gait from bilateral alternation to synchrony midway through digging. In E. analoga, right and left legs 2 and 3 always alternate. Legs 4 can cycle at about twice the frequency of legs 2 and 3, and they tend to move in bilateral synchrony during high-frequency leg movements (e.g. at the start of digging); their bilateral coupling becomes variable during low-frequency movements. Sand crab digging may have originated as a modified form of walking, but this behavioural innovation subsequently diverged in the sand crab superfamily.

Journal Article↗
PubMed1998

The functioning of the haemocyanin of the terrestrial christmas island red crab gecarcoidea natalis and roles for organic modulators

Gecarcoidea natalis is a land crab that migrates annually several kilometres to breed. The O2-binding properties of haemocyanin in G. natalis were investigated in vitro to test the idea that the O2-binding properties of the haemocyanin of land crabs are not dependent on circulating modulators and to provide a model of haemocyanin functioning during exercise. The affinity of the haemocyanin for O2 decreased with increasing temperature (change in the heat of oxygenation; capdelta H=-59 kJ mol-1). The haemocyanin of G. natalis apparently differs from that of other terrestrial crabs in showing haemocyanin O2 modulation by both organic and inorganic molecules. Haemocyanin O2-affinity was not affected by Mg2+ but was sensitive to changes in Ca2+ concentration ( capdelta logP50/ capdelta log[Ca]=-0.61, where P50 is the partial pressure of O2 required for half-maximal O2 binding). The Bohr factor was modest ( &phgr; =-0.26+/-0.03, N=4, in whole haemolymph at 25 degreesC) and there was no specific effect of CO2 on the O2-binding properties of the haemocyanin. An increase in urate concentration increased haemocyanin O2-affinity, but the effect was linear ( capdelta logP50/ capdelta [urate]=-0.06) and not logarithmic as is the case in other species. The effect of l-lactate on the haemocyanin O2-affinity in G. natalis was unique among the crustaceans, because an increase in l-lactate concentration decreased the haemocyanin O2-affinity. The effect of l-lactate on haemocyanin O2-affinity ( capdelta logP50/ capdelta log[lactate]) was time-dependent and decreased from a maximum of 0.044 on day 1 to 0.001 after 4 days of storage at 4 degreesC. The presence of an unknown dialysable and unstable factor in the haemolymph is postulated to explain the time-dependent effect of l-lactate on haemocyanin O2-binding properties. Model oxygen equilibrium curves constructed for in vivo conditions showed that the reverse effect of l-lactate was advantageous by decreasing the O2-affinity of the haemocyanin beyond that predicted by the Bohr shift alone and assisted in O2 off-loading at the tissues. This effect of lactate can only provide an advantage if the gas-exchange organs maintain arterial O2 loading and thus is dependent on lung function in land crabs and must have occurred coincident with the evolution of these other features.

Journal Article↗
PubMed1998

Roles of eyes, leg proprioceptors and statocysts in the compensatory eye movements of freely walking land crabs (Cardisoma guanhumi)

The compound eyes, the canal organs of the statocysts and proprioceptors in the legs all generate compensatory eye movements in the horizontal plane in the land crab Cardisoma guanhumi. Frequency analyses of the compensatory eye reflexes elicited by each of these inputs show that visual (V) and proprioceptive (P) reflexes respond best below 0.1 Hz, while statocyst (S) reflexes only achieve a high gain above this frequency. They thus increase the range of frequencies over which compensation can occur. Eye and body movements were recorded in an arena under all possible combinations of crabs seeing or blind (V+ or V-), with or without statocysts (S+ or S-) and freely walking or passively transported on a trolley (P+ or P-). Intact crabs (V+S+P+) show good stabilisation of the eyes in space, the only movements with respect to external coordinates being saccadic resetting movements (fast phases of nystagmus). The eyes thus compensate well for body turns, but are unaffected by translatory movements of the body and turns that are not accompanied by a change in the orientation of the long axis of the body in space. In the absence of any one sense, compensation for rotation is significantly impaired, whether measured by the increase in the width of the histograms of changes in the angular positions of the eyes in space ( capdelta &phgr; E), by the mean angular velocity of the eyes (slope of regression line, mE) with respect to the angular velocity of the body (mB) or by response gain plotted against angular acceleration of body turn (a). The absence of two senses reduces the crab's ability to compensate still further, with the statocyst-only condition (V-S+P-) being little better than the condition when all three senses are absent (V-S-P-).Such multisensory control of eye compensation for body rotation is discussed both in terms of making use of every available cue for reducing retinal slip and in making available the information content of the optic flow field.

Journal Article↗
PubMed1998

Salt and water relations, and nitrogen excretion, in the amphibious african freshwater crab potamonautes warreni in water and in air

Mechanisms of salt and water conservation, and nitrogen excretion, were investigated in the freshwater amphibious crab Potamonautes warreni from the High Veld of South Africa. Adaptations to fresh water were assessed as pre-adaptations to air-breathing, and nitrogen excretion was examined as a potential constraint to terrestrial excursions. P. warreni was able to regulate water and salt loss in water up to 40 % sea water, but not in 80 % sea water. The water permeability of P. warreni was low and, since 97 % of the haemolymph filtrate was reabsorbed in the antennal organ, urinary water loss was minimal (0.7 microl g-1 h-1). The minimum equilibrium [Na] of P. warreni was low (0.116 mmol l-1), as were the rates of both Na loss (0.22 micromol g-1 h-1) and Ca loss (0.29 micromol g-1 h-1). The low loss rates were due to urinary salt conservation of approximately 90 % or better and to low permeability (K'Na=0.0025; K'Ca=0.0521), and were compensated for by a high-affinity uptake mechanism (Jmax=0.76 micromol g-1 h-1 and Km=0.18 mmol l-1). Acclimating P. warreni to low Na concentrations increased maximum net Na uptake rate to 1.77 micromol g-1 h-1. Nitrogen excretion in P. warreni was almost 100 % ammoniotelic, and there was no accumulation of haemolymph or urinary ammonia or urea when in air. P. warreni was unable to excrete ammonia to air, but in water the rate of excretion was nearly 70 micromol kg-1 h-1. Crabs in amphibious conditions showed pulses of elevated NH3 excretion (350 micromol kg-1 h-1) when subsequently submerged, while for crabs breathing air for 3 days this pulse reached 4.9 mmol kg-1 h-1. Air-breathing P. warreni with artificially irrigated branchial chambers excreted double the amount of NH3 via the gills compared with crabs from amphibious conditions. Water and salt conservation form useful pre-adaptations to terrestrial forays. While the relatively low water loss extends the duration of emersion, P. warreni is required to return briefly to water to excrete stored nitrogenous waste. The nature of the store remains to be determined.

Journal Article↗
PubMed2000

Expression of arginine kinase enzymatic activity and mRNA in gills of the euryhaline crabs Carcinus maenas and Callinectes sapidus.

Phosphagen kinases catalyze the reversible dephosphorylation of guanidino phosphagens such as phosphocreatine and phosphoarginine, contributing to the restoration of adenosine triphosphate concentrations in cells experiencing high and variable demands on their reserves of high-energy phosphates. The major invertebrate phosphagen kinase, arginine kinase, is expressed in the gills of two species of euryhaline crabs, the blue crab Callinectes sapidus and the shore crab Carcinus maenas, in which energy-requiring functions include monovalent ion transport, acid-base balance, nitrogen excretion and gas exchange. The enzymatic activity of arginine kinase approximately doubles in the ion-transporting gills of C. sapidus, a strong osmoregulator, when the crabs are transferred from high to low salinity, but does not change in C. maenas, a more modest osmoregulator. Amplification and sequencing of arginine kinase cDNA from both species, accomplished by reverse transcription of gill mRNA and the polymerase chain reaction, revealed an open reading frame coding for a 357-amino-acid protein. The predicted amino acid sequences showed a minimum of 75 % identity with arginine kinase sequences of other arthropods. Ten of the 11 amino acid residues believed to participate in arginine binding are completely conserved among the arthropod sequences analyzed. An estimation of arginine kinase mRNA abundance indicated that acclimation salinity has no effect on arginine kinase gene transcription. Thus, the observed enhancement of enzyme activity in C. sapidus probably results from altered translation rates or direct activation of pre-existing enzyme protein.

Amino Acid Sequence↗
PubMed2000

High environmental salinity induces memory enhancement and increases levels of brain angiotensin-like peptides in the crab Chasmagnathus granulatus.

Previous work on the brackish-water crab Chasmagnathus granulatus demonstrated that an endogenous peptide similar to angiotensin II plays a significant role in enhancing long-term memory that involves an association between context and an iterative danger stimulus (context-signal memory). The present results show that this memory enhancement could be produced by moving crabs from brackish water to sea water (33.0%) and keeping them there for at least 4 days. The possibility that such a facilitatory effect is due to osmotic stress is ruled out. Coincidentally, the level of angiotensin-II-like peptides in crab brain, measured by radioimmunoassay, increases with the length of exposure to sea water, reaching a significantly different level at the fourth day. The presence of angiotensin-II-like immunoreactive material in neural structures of the supraoesophageal and eyestalk ganglia was confirmed by immunohistochemical analysis. The results are interpreted as supporting the hypothesis that exposure to water of high salinity is an external cue triggering a process mediated by angiotensins that leads to enhanced memory in these crabs.

Angiotensin II↗
PubMed2000

Agonistic behaviour and biogenic amines in shore crabs Carcinus maenas.

To investigate the role of certain neurohormones in agonistic behaviour, fights were staged between pairs of size-matched male shore crabs Carcinus maenas, and blood samples were taken immediately after the contests had been resolved. Samples were also taken from these crabs at rest (before and after fighting) and after walking on a treadmill. A control group of crabs also had samples taken on each experimental day. Concentrations of tyramine, dopamine, octopamine, serotonin (5-HT) and norepinephrine were determined in each blood sample using a gas chromatography/mass spectrometry (GC-MS) system. Norepinephrine was not detectable in any of the samples, but the standards were recovered. Tyramine values were not significantly different between the control group and the fought group, so tyramine does not appear to be important in agonistic behaviour. A comparison between the control and fought groups shows that fighting had an effect on the concentrations of octopamine, dopamine and 5-HT, but exercise only had an effect on octopamine levels, which showed a reduction from resting values in both winners and losers. Resting and post-fight concentrations of octopamine, dopamine and 5-HT were higher in winners than in losers. 5-HT concentration increased in the blood of fought crabs from resting values, whereas dopamine concentration decreased. In winners, octopamine concentrations decreased from resting values, but in losers octopamine levels increased from resting concentrations. The escalatory behaviour or intensity of fighting performed by winners and losers was related to dopamine levels but not to those of octopamine or 5-HT. Therefore, there appears to be a link between relative concentrations of these three amines (dopamine, octopamine and 5-HT) and fighting ability; the effects are not simply a result of activity. The better competitors have higher concentrations of these three amines at rest and after fighting.

Agonistic Behavior↗
PubMed2001

Na(+)+K(+)-ATPase in gills of the blue crab Callinectes sapidus: cDNA sequencing and salinity-related expression of alpha-subunit mRNA and protein.

Many studies have shown that hyperosmoregulation in euryhaline crabs is accompanied by enhanced Na(+)+K(+)-ATPase activity in the posterior gills, but it remains unclear whether the response is due to regulation of pre-existing enzyme or to increased gene transcription and mRNA translation. To address this question, the complete open reading frame and 3' and 5' untranslated regions of the mRNA coding for the alpha-subunit of Na(+)+K(+)-ATPase from the blue crab Callinectes sapidus were amplified by reverse transcriptase/polymerase chain reaction (RT-PCR) and sequenced. The resulting 3828-nucleotide cDNA encodes a putative 1039-amino-acid protein with a predicted molecular mass of 115.6 kDa. Hydrophobicity analysis of the amino acid sequence indicated eight membrane-spanning regions, in agreement with previously suggested topologies. The alpha-subunit amino acid sequence is highly conserved among species, with the blue crab sequence showing 81-83 % identity to those of other arthropods and 74-77 % identity to those of vertebrate species. Quantitative RT-PCR analysis showed high levels of alpha-subunit mRNA in posterior gills 6-8 compared with anterior gills 3-5. Western blots of gill plasma membranes revealed a single Na(+)+K(+)-ATPase alpha-subunit protein band of the expected size. The posterior gills contained a much higher level of alpha-subunit protein than the anterior gills, in agreement with previous measurements of enzyme activity. Immunocytochemical analysis showed that the Na(+)+K(+)-ATPase alpha-subunit protein detected by alpha5 antibody is localized to the basolateral membrane region of gill epithelial cells. Transfer of blue crabs from 35 to 5 per thousand salinity was not accompanied by notable differences in the relative proportions of alpha-subunit mRNA and protein in the posterior gills, suggesting that the enhanced Na(+)+K(+)-ATPase enzyme activity that accompanies the hyperosmoregulatory response may result from post-translational regulatory processes.

Amino Acid Sequence↗
PubMed1996

PCDDs, PCDFs, and PCBs in human blood in relation to consumption of crabs from a contaminated Fjord area in Norway.

Consumption of fish and shellfish from contaminated areas may be an important source of human exposure to persistent organohalogen compounds such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). We determined concentrations of 2,3,7,8-substituted PCDDs and PCDFs and 19 PCB congeners in whole blood samples from three groups of men, 40-54 years of age, with different consumption levels of crabs from a fjord area in southern Norway polluted with organochlorine compounds from a magnesium production plant. A significant increase of many PCDD/PCDF congeners was found in the blood when comparing the referents, moderate-, and high-intake groups. The greatest difference was observed for several of the PCDFs that are characteristic for the contamination of the marine biota of the fjord. PCBs, in general, play a minor role in the contamination of the fjord by the magnesium production process, except for the highly chlorinated congeners such as PCB-209. Nevertheless, almost all PCBs increased from the referents to the high-intake group. However, the relative concentrations of several highly chlorinated PCBs (particularly PCB-209) in blood are unexpectedly low compared to their abundance in crabs, indicating low uptake of these congeners. The exposure to PCDDs/PCDFs from crab consumption calculated from individual body burdens of these compounds were in good agreement with the intake estimated from previously measured concentrations in crabs, reported fishing sites, and consumption. Almost all subjects in the high-intake group exceeded the tolerable weekly intake of 35 pg TEQ/kg body weight/week proposed by a Nordic Expert Group.

Adult↗
PubMed2003

Larval spirurida (Nematoda) from the crab Macrophthalmus hirtipes in New Zealand.

Previously undescribed third-stage larvae of two species of Spirurida were found in the haemocoel of the stalk-eyed mud crab Macrophthalmus hirtipes (Heller) (Ocypodidae) in New Zealand. Examinations by light and scanning electron microscopy showed that the larger larvae (about 7 mm long) belonged to a species of Ascarophis van Beneden, 1871 (Cystidicolidae), the genus including parasites of fishes, whereas the smaller larvae (about 4-5 mm long) belonged to the Acuariidae, a family with species parasitic as adults mostly in aquatic birds. In a sample of 82 specimens of M. hirtipes collected in July 2002 from Papanui Inlet, on Otago Peninsula, South Island, 74 crabs (90.2%) were infected with larval nematodes with an intensity of 1-18 (mean 4.6) nematodes per crab; no distinction between nematode species was made in these estimates, although juvenile Acuariidae greatly outnumbered larval Ascarophis. Apparently, crabs play a role as intermediate hosts of these nematode species. This is the first record of larval representatives of Cystidicolidae and Acuariidae from invertebrates in the Australasian Region.

Animals↗
PubMed1984

[Morphological observations on the cranial and facial bones of the crab-eating monkey].

Forty seven skulls of the crab-eating monkey (Macaca fascicularis) were investigated for their morphological characteristics. Five of them were disintegrated into component bones by the use of the papain. Each cranial and facial bone of this species resembled that of the rhesus monkey (M. mulatta) in its general morphology. Some obvious differences, however, were noticed in the detailed structure of the skulls between these two species. The uncinate process of the ethmoid bone was found in the rhesus monkey but was not found in the crab-eating monkey. The intrajugular process of the temporal and occipital bones was present in the crab-eating monkey but absent in the rhesus monkey. The nasal process of the incisor bone was sutured with frontal bone in the rhesus monkey but was not sutured with that bone in the crab-eating monkey.

Animals↗
PubMed2006

Bio-ecological aspects of the hermit crab Paguristes calliopsis (Crustacea, Diogenidae) from Anchieta Island, Brazil.

In southern Atlantic studies on hermit crab biology are scanty considering the local biodiversity. In this way, some population features of Paguristes calliopsis Forest and Saint Laurent, 1968 such as size frequency distribution, sex ratio and shell occupation in the natural environment were studied. Specimens were collected by means of scuba methods in the infralittoral area of the Anchieta Island. A total of 116 individuals were analyzed. Size measurements (minimum; maximum; mean shield length +/- sd, respectively) were 0.8; 4.5; 2.76 +/- 0.79 mm for males and 2.28 +/- 0.36 mm for females. The sex ratio was 1.47:1 in favor of males which prevailed in the largest size classes. The hermit crabs occupied shells from eleven gastropod species and Cerithium atratum (Born 1778) was significantly the most occupied one (75.86%). Significant correlations were not obtained in all regression analysis, demonstrating sexual differences on fitting of the occupied shells. In the studied area P. calliopsis population is small if compared with the other hermit crab populations. The shell utilization varies as a function of shell availability and hermit crabs interspecific competition, in relation to the other coexistent species.

Animals↗
PubMed2000

Clustering behavior of hermit crabs (Decapoda, Anomura) in an intertidal rocky shore at São Sebastião, southeastern Brazil.

The clustering behavior and cluster composition of hermit crabs as well as the patterns of shell utilization of clustered and scattered individuals were studied. This study was conducted in the intertidal region of Grande Beach, São Sebastião, southeastern Brazil. Samples were taken both in randomized transects and 1 m2 quadrats during low tide periods. Crabs were counted, measured (shield length), and sexed. Shells were identified and had their adequacy and condition (physical damage and incrustation) recorded. Clusters occurred mainly in air exposed areas and were dominated or composed only by Clibanarius antillensis. Other species like Paguristes tortugae, Pagurus criniticornis, and Calcinus tibicen were also present in these clusters, but in small numbers. Only one monospecific aggregation composed by individuals of P. criniticornis was recorded in tide pools. Almost all crabs were inactive, despite some that were submerged in tide pools. Most of the individuals of C. antillensis were clustered (70.88%). Scattered individuals were larger than clustered ones and occupied mainly shells of Tegula viridula, which seemed to be the most adequate shell to the crabs. Clustered individuals used less incrusted shells than isolated ones. In general, clustering in Grande Beach presented the same patterns of size and sex distribution, and shell utilization than others already studied, with the exception of the smaller cluster size registered in this area.

Animals↗
PubMed2005

Lethargic crab disease: multidisciplinary evidence supports a mycotic etiology.

Although lethargic crab disease (LCD) is causing massive mortalities in populations of the mangrove crab Ucides cordatus of Northeastern Brazil, the identity of its etiological agent was hitherto unknown. In this study we provide robust evidence suggesting that LCD is caused by an anamorph Ascomycota (Fungi). We examined specimens of U. cordatus collected from stocks affected by LCD. Histological and TEM methods detected the presence of hyphae, conidia, and condiophores in several host tissues. Moreover, the abundance of fungal stages is negatively associated with crab health. Finally, DNA was isolated from the fungus and a region of its 18S ribosomal gene was sequenced Phylogenetic analyses not only confirm the diagnosis of the LCD fungus in crab tissues as an ascomycete, but also suggest a close relationship with members of the subphylum Pezizomycotina.

Animals↗
PubMed2002

Substrate use and selection in sympatric intertidal hermit crab species.

Coexisting hermit crabs may competitively interact for shells and microhabitats, mainly when shell availability is habitat-related. Three species of Clibanarius (C. antillensis, C. sclopetarius, and C. vittatus) coexist in the intertidal region of Pernambuco Islet, Araçá Region, São Sebastião Channel, southeastern Brazil. This study evaluated crab preferences for four substrate types used by these species in nature (rocky shore, pebbles, sand, and mud) in allopatric (single species) and sympatric (three species) treatments in simulations of high tide and low tide. The substrate preference of the three hermit crabs did not vary between low and high tide situations. At low tide the crabs either moved into holes in the highly complex rocky substrate or buried themselves in mud. Substrate selection may explain the patterns of substrate use in nature only for C. vittatus. Clibanarius antillensis and C. sclopetarius showed closer similarities in the pattern of substrate selection in the sympatric treatment with the substrate use in nature than in allopatric treatment, indicating a positive influence (dependence) of the presence of one species on the presence of another. Use of sub-optimal substrates, mainly by C. antillensis, may be caused by other factors such as its low desiccation tolerances. If competition for space takes place among these species, it would be more intense between C. sclopetarius and C. vittatus given their higher overlap in substrate preference than between them and C. antillensis.

Animals↗
PubMed2003

Effect of low salinity on cadmium accumulation and calcium homeostasis in the shore crab (Carcinus maenas) at fixed free Cd2+ concentrations.

Increased Cd toxicity at low salinity has been attributed to increased free Cd2+ ion concentration ([Cd2+]sw), but transfer to dilute seawater also stimulates physiological ionic regulation in crabs. In this study, Cd accumulation and Ca homeostasis in the shore crab (Carcinus maenas) were explored at fixed [Cd2+]sw to reveal the physiological events during sublethal Cd exposure. Crabs were exposed to 3.4 or 34 microg/L [Cd2+], in both 100% seawater (SW) and 33% SW for up to 10 d and sampled for hemolymph composition as well as gill and hepatopancreas Ca, Cd, and Ca-ATPase activity. Cadmium exposure ameliorated the expected fall in hemolymph osmotic pressure and NaCl at low salinity and generally protected tissue Ca from decline. Cadmium exposure alone (within salinity) inhibited Ca-ATPase, but this was offset by stimulation of Ca-ATPase at low salinity. The Ca-ATPase activity in the anterior and posterior gills showed different responses to Cd/low salinity stress. Crabs were more sensitive to a 10-fold increase in [Cd2+]sw at low salinity. Overall, we conclude that exposure to a fixed sublethal [Cd2+]sw reveals a compensatory physiological response that is driven primarily by salinity rather than Cd2+ free ion concentration. Physiological responses are therefore important during low-level Cd exposure in dilute seawater.

Animals↗
PubMed1975

A comparison of thermoregulatory responses in the Japanese macaque (Macca fuscata) and the crab-eating macaque (Macaca irus) during cold exposure.

Thermoregulatory responses in four male adult Japanese macaques and four male adult crab-eating macaques, weighing 6-12 kg and 6.2-8 kg, respectively, were compared at ambient temperatures (Ta) ranging from 5 degrees C to 25 degrees C. The average values +/- S.E. for some physiological measurements made at Ta of 25 degrees C in the Japanese macaque and the crab-eating macaque, respectively, were as follows: resting metabolic rate; 47.6 +/- 5.0 and 42.5 +/- 1.7 W/M2; tissue conductance; 11.9 +/- 0.8 and 8.9 +/- 0.8 W/M2/degrees C; respiratory evaporative heat loss; 4.1 +/- 0.3 and 3.2 +/- 0.5 W/M2; rectal temperature; 38.6 +/- 0.1 and 37.4 +/- 0.2 degrees C; mean skin temperature; 34.0 +/- 0.3 and 31.2 +/- 0.1 degrees C. When Ta was lowered stepwise from 25 degrees C to 20, 15, 10, and 5 degrees C successively, and maintained constant at each temperature level for 1 hr, metabolic heat production graudually increased in both species. Whe Ta was lowered from 10 degrees C to 5 degrees C, the crab-eating macaque did not show further increase in heat production and the result was a loss of thermal equilibrium with rectal temperature continuing to fall. On the other hand, the Japanese macaque maintained thermal balance even at Ta of 5 degrees C. Tissue conductance, which was significantly higher in the Japanese macaque than in the crab-eating macaque at Ta of 5, 15, and 25 degrees C, decreased in both species at Ta was lowered from 25 degrees C to 15 and 5 degrees C. The specific differences in thermo-regulatory responses are considered to be adaptational, relative to the natural habitat of thw two species studied.

Animals↗