Eccritic Temperature Research Articles

Diel temperature patterns of juvenile lemon sharks Negaprion brevirostris, in a shallow‐water nursery

The relatively complex pattern of temperature selection exhibited by juvenile lemon sharks Negaprion brevirostris in the North Sound differed markedly from many previously described responses of fish preferenda. Thermal data demonstrated that juvenile N. brevirostris did not attempt to behaviourally maintain a constant eccritic temperature. Rather, juveniles selected progressively warmer temperatures throughout the day until reaching the highest temperatures available, and then moved to cooler temperatures during late evening and early morning hours. It is possible that by exploiting habitat thermal heterogeneity juvenile N. brevirostris prolong activities such as feeding or digestion well into the cooler parts of the evening. The complex pattern of temperature occupation by juvenile N. brevirostris within the thermally heterogeneous North Sound nursery is probably linked to key daily activities such as prey capture, predator avoidance and digestive efficiency.

Movement of Rotylenchulus Reniformis Through Sand and Agar in Response To Temperature, and Some Observations On Vertical Descent

The movement of vermiform stages of Rotylenchulus reniformis in response to a temperature gradient of 1°C per cm was investigated in 4 cm diam tubes containing 0.75% water agar or moist sand graded to 150-250 μm and 250-425 μm particle sizes. Nematodes previously stored at 30°C exhibited a temperature preferendum, or eccritic temperature, of 30°C and nematodes stored at 17°C exhibited a preferendum of 23°C in both matrices. In sand of 250-425 μm particle size, most nematodes moved 10 cm downward within 17 h. Rapid downward movement occurred regardless of moisture content or moisture gradient direction. Only living nematodes moved downward and 90% of 1,000 live nematodes that were videotaped as they descended in a narrow channel of water descended in a head downward postition.

The relationship of blood oxygen affinity to body size in lizards

1. 1. Oxygen affinity of whole blood of 51 species of lizards from 12 families was measured at the eccritic temperature of each species. 2. 2. Blood oxygen affinity was lower than that of birds or mammals and increased with increasing body size. 3. 3. Iguanid lizards were used as a basis for comparisons of other families. Blood oxygen affinity of lizards in the families Agamidae, Cordylidae, Lacertidae and Varanidae did not differ from that of iguanids of comparable body size. 4. 4. Teiid and anguid lizards had lower oxygen affinities than iguanids. possibly reflecting their more active lives. 5. 5. Scincid and chamaeleonid lizards had higher blood oxygen affinities than iguanids, apparently as a result of their lower eccritic temperatures. 6. 6. Geckonid and xantusiid lizards had higher blood oxygen affinities than iguanids at their normally low eccritic temperatures and at higher temperatures comparable to eccritic temperatures of iguanid lizards.

Body temperature of the lizard (Anolis carolinensis): effect of parietalectomy.

Thermal behavior of parietalectomized, sham-parietalectomized or intact lizards (Anolis carolinensis) was recorded in a test chamber containing moving photothermal gradients. Following parietalectomy, animals chose significantly higher temperatures than sham-parietalectomized or intact control animals, which chose lower and statistically identical temperatures. When pre-surgical and post-surgical means are compared within groups, the eccritic temperature was 2.10 degrees C higher following parietalectomy, 0.72 degrees C higher following sham-parietalectomy, and 0.31 degrees C higher in intact controls during the post-operative measurements. The effects of parietalectomy indicate that the parietalpineal complex may be involved in behavioral thermoregulation by precisely regulating exposure to heat sources (e.g. sunlight).

The Effect of Temperature on Oxygen Capacity of Reptile Blood

Oxygen capacity of reptile blood in vitro is temperature sensitive and is reversibly reduced as much as 40% at the extremes of the temperature range that animals normally encounter. In several species of lizards and snakes, blood oxygen capacity is maximum within the species' activity-temperature range. The correlation coefficient between eccritic temperature and the temperature giving maximum blood oxygen capacity for all species tested was .79 (P < .01). (When the genera Sceloporus and Uta, which show a different pattern, are omitted from the analysis, the correlation coefficient for the remaining species rises to .92.) This adaptation of the blood is one of the mechanisms that produces maximum oxygen consumption near a species' eccritic temperature. In lizards of the genera Sceloporus and Uta and in turtles the maximum blood oxygen capacity occurs at the bottom of the activity-temperature range and may reflect adaptation of these animals to activity at low temperatures.

Thermal Ecology of the Lizard, Anolis Limifrons with Comparative Notes on Three Additional Panamanian Anoles

Data on the thermoregulation of Anolis limifrons in Panama suggest that at least some tropical species are less warm adapted than previously thought. Anolis limifrons has a lower minimum voluntary temperature, eccritic temperature, and critical thermal maximum than a majority of the temperate zone lizards thus far studied. Thermoregulatory adjustment is by behavioral mechanisms as indicated by observations on basking and orientation. A seasonality in the preferred temperature is indicated by field data from the wet and dry seasons. It is suggested that the lower preferred temperature in the dry season is an adaptation to conserve water or minimize water loss. Anoles (A. limifrons and A. frenatus) in colsed canopy forests are less warm adapted than the grassland A. auratus, whereas an ecotone species (A. tropidogaster) is intermediate in its thermoregulatory characteristics. Differences in dermal morphology in three species of Panamanian anoles are suggested to be an adaptation to varied capacities of heat gain.

Acclimatization in the Eccritic Thermal Response of Ditylenchus Dipsaci

The eccritic temperature or thermal preferendum of D. dipsaci in a heat gradient has been investigated with respect to acclimatization. By storing D. dipsaci at 10°, 20°, and 30° C for 30 days and then introducing them into a heat gradient it was found that they accumulated at temperatures which corresponded to the storage temperature; acclimatization had therefore occurred. They also showed greatest activity at their storage temperatures.

Ecological Distribution in Anoline Lizards of Puerto Rico

The eight species of lizards of the genus Anolis in Puerto Rico can be divided into four morphological similarities. One, Anolis curvieri, is very different from the rest and has not been discussed here. The other seven species fall into three groups. Each of these groups occupies a different structural habitat which can be defined in terms of perch height and perch diameter. Within each of these three groups the species have very similar but not indential structural habitats but differ very widely in climatic habitat defined in terms of shade. Shade preferences seem to result from the temperature preferences of the species involved. In each group there is one species with high shade preference which is essentially restricted to the mountains. Each group also has a species with a lower shade preference which occurs in the lowlands and extends up into the mountains in exposed or sunny situations. One of the three groups has an additional species which is restricted to the hot and southwest corner of Puerto Rico. When one compares the temperature preferences or eccritic temperatures of the various species, one finds in each group that the highland species has a lower eccritic temperature than does the lowland species. There is little temperature difference between the lowland species and arid southwest species in the group where this additional third species is present. The species within each structural habitat show many morphological similarities which may be the result of their being closely related or may be the result of adaptation to similar environments. The differences in microhabitat between the Puerto Rican anoles separate them spatially though not completely. In species occupying different structural habitats in the same area the overlap may involve part of the home range of most of the individuals in the area. In species occupying the same structural but different climatic habitats the overlap may involve all of the home range of some individuals but of only a small fraction of the individuals in the total population. The spatial separation among Puerto Rican Anolis can be suggested to be of ecological significance because it reduces interspecific competition and because it allows the various species to adapt more precisely to different parts of the available habitat. Thus members of a genus may exploit the habitat more efficiently.