Green Frog Tadpoles Research Articles

Effects of Temperature and Illumination on Feeding Rates of Green Frog Tadpoles (Rana clamitans)

ate significantly less than at those at 23 C or 26 C, but feeding rates did not differ at the two higher temperatures. Feeding rates in the laboratory were similar to those measured in open areas of a pond at the same temperatures; temperature alone may explain some feeding rate variation in natural systems. Tadpoles in the light and in the dark ate similar amounts. A nocturnal decline in feeding rates observed in nature cannot be attributed to darkness.

Evidence of a Chemically-Mediated Avoidance Response of Ovipositing Insects to Blue-Gills and Green Frog Tadpoles

Evidence of a Chemically-Mediated Avoidance Response of Ovipositing Insects to Blue-Gills and Green Frog Tadpoles

Responses of green frog (Rana Clamitans) tadpoles to lead-polluted water

Green frog (Rana clamitans) tadpoles were exposed to 0, 500, 750 and 1,000 μg Pb/L (as lead nitrate) for 6 d (144 h). Previous studies have shown that similar exposure to 750 or 1,000 μg Pb/L produces deficiencies in both acquisition and retention of learned responses in green frog tadpoles. We examined preference/avoidance responses and spontaneous locomotor activity of Pb-exposed and control tadpoles to plumes of Pb-polluted water at each concentration in an octagonal fluviarium. Results indicated no significant preference or avoidance of Pb by either control or Pb-exposed animals, and no significant effects on the amount of locomotor activity. However, there was significantly greater (p < 0.05; folded Ftest) variability in locomotor activity for tadpoles exposed to 750 and 1,000 μg Pb/L compared to control animals and to those exposed to 500 μg Pb/L.

Sublethal exposure to lead inhibits acquisition and retention of discriminate avoidance learning in green frog (Rana Clamitans) tadpoles

AbstractGreen frog, Rana clamitans, tadpoles were exposed to 750 μg Pb/L as lead nitrate. Tadpoles used in learning acquisition tests were exposed for 6 d (144 h) and tadpoles used in retention (memory) tests were exposed for 5 d (120 h). Both lead‐exposed and control tadpoles were conditioned, using shock avoidance, to associate illumination (conditioned stimulus) with shock (unconditioned stimulus). The mean response time, the number of avoidances and differences in the learning curves of the lead‐exposed and control tadpoles were compared statistically. Learning acquisition tests showed increased response times and fewer avoidances in lead‐exposed as compared to control tadpoles. Retention tests showed higher response times and no avoidances in lead‐exposed tadpoles as compared to controls. These results indicate that sublethal exposure to lead adversely affected both acquisition learning and memory.

Lead concentrations in bullfrog Rana catesbeiana and green frog R. clamitans tadpoles inhabiting highway drainages

Lead concentrations were determined in sediment and tadpoles of bullfrogs Rana catesbeiana and green frogs R. clamitans from drainages along highways with different daily average traffic volumes (range, 4272 to 108 800 vehicles day −1) and from ponds ≥ 0·4 km from the nearest highway. Lead concentrations (mg kg −1 dry weight) in sediment (7·8 to 940) were usually greater (4–5 times) than those in the tadpoles (bullfrog, 0·07 to 270; green frog, 0·90 to 240 mg kg −1). Lead concentrations in sediment ( r = 0·63) and in both species of tadpoles (bullfrog, r = 0·69; green frog, r = 0·57) were positively correlated with average daily traffic volume. Lead concentrations in both species of tadpoles (bullfrog, r = 0·76; green frog, r = 0·75) were also positively correlated with lead concentrations in sediment. At sites where both bullfrog and green frog tadpoles were collected, lead concentrations in the two species were closely related ( r = 0·84). Lead concentrations in tadpoles living near highways may contribute to the elevated lead levels reported in wildlife that are potential tadpole predators. Dietary lead concentrations similar to those in our tadpoles have been associated with physiological and reproductive effects in some species of birds and mammals. However, additional data are needed to determine the hazards to predators of lead concentrations in tadpoles.

Host‐Parasite Interaction as a Potential Population‐Regulating Mechanism

Candida humicola, a parasitic yeast occuring in the gut of Green frog (Rana clamitans) tadpoles, enhanced the growth of tadpoles of this species under certain conditions. Low concentrations of C. humicola (1—10 cells per millilitre) increased the growth rate of tadpoles relative to siblings raised under identical conditions but without C. hunicola cells. Furthermore, the impact of a given concentration of C. humicola cells varied inversely with the size of the tadpole. Candida humicola appears to act as a mutualistic symbiont of the larger tadpoles and as a parasite of the small ones. Because larger tadpoles are more likely than their smaller siblings to metamorphose and reproduce, the mutualism benefits those individuals which are most likely to contribute to the continuation of the Green frog population. For this reason, resistance to the parasitism is not likely to develop. The parasite may act to regulate the adult Green frog population size by altering the probability of metamorphosis of individual tadpoles.

Pharyngodon armatus Walton, 1933 (Nematoda: Oxyuridae); Description of the Male and Redescription of the Female

Pharyngodon armatus was originally described from female specimens only. Male and female specimens have been recovered from the intestine of green frog tadpoles (Rana clamitans melanota). The male of the species is described for the first time and the female is redescribed. Male and female specimens of the genus Pharyngodon were recovered from the intestine of green frog tadpoles (Rana clamitans melanota) collected from Pond 26, Delaware Game Preserve, Delaware County, Ohio. Seven species of Pharyngodon have been reported from amphibians by Walton (1929, 1933, 1940), Baylis (1930), Yamaguti (1941), Johnston and Mawson (1942), and Ubelaker (1965). Only three of the seven species have been described on the basis of male and female specimens. Pharyngodon spinicauda, the type species, was originally described from the reptile, Lacerta muralis. It has since been recovered from Triturus vulgaris. Pharyngodon armatus was described from female specimens only by Walton (1933). While reviewing a type specimen of P. armatus obtained from the USNM Helm. Coll. No. 27061, I noted discrepancies in the original description of the females. Inconsistencies included the position of the excretory pore, operculum on the eggs, the prominence of the lips, and the beginning of cuticular striations. The newly recovered females were conspecific with the type specimen. Since the original description was incomplete and since male specimens were recovered, I have deposited the Ohio specimens and the following description of the male and redescription of the female are given. MATERIALS AND METHODS The nematodes were fixed in steaming 70% alcohol and cleared in alcohol-glycerine. Living and fixed specimens were examined with light and phase contrast microscopes. The 25 male and 25 female specimens used in this study were temporarily mounted under supported cover slips. All measurements are in microns, unless otherwise Received for publication 6 August 1968. indicated. The range is followed by the average in parentheses. Drawings were made with the aid of the camera lucida. Pharyngodon armatus Walton, 1933 (Figs. 1-8)

Observations and Experiments on the Opalinid Ciliates of the Green Frog

This is a continuation of studies begun a number of years ago (Hegner, 1922) because of the fact that the tadpole of green frogs and bull frogs have a high incidence of infection with opalinids, whereas the adults are usually free from these ciliates, although both tadpoles and adults of other American frogs are infected. The chief questions involved are (1) when and why do green frog tadpoles lose their opalinids and (2) why do not adult green frogs become reinfected? Green frogs, leopard frogs and tree frogs from Mount Desert Island, Maine, were studied during the summer of 1930 in an attempt to answer these questions. Do adult green frogs on Mount Desert Island, Maine, harbor opalinids? This was the first problem undertaken. Ten adult green frogs of various sizes, and presumably of various ages, were examined. No opalinids were found. Ciliates of the genus Nyctotherus were present in the rectum of one specimen; trichomonads were present in large numbers in all; hexamitas were found in nine, but were few in number. At what stage does the green frog lose its opalinids? To answer this question tadpoles were separated into three groups as follows: (1) without external legs, (2) with two posterior legs, and (3) with four legs. The lengths of body, tail and intestine were obtained for those with two and four legs and presented in the following table.