Many studies have been done on the neural control of serous gland secretion in the skin of frogs and newts. However, no studies have been published on the effects of adrenergic and cholinergic neurotransmitters on the sexually dimorphic breeding glands of male frogs. The present study examined the effects of neurotransmitters on the serous and breeding glands of Hymenochirus curtipes. Explants of dorsal skin and postaxial skin (containing whole breeding glands) were incubated in vitro with epinephrine, norepinephrine or acetylcholine for 30 minutes. The explants were then preserved and examined histologically for signs of secretion. The area and perimeter of the serous and breeding glands were measured before (control groups) and after the treatments. Epinephrine and norepinephrine treatments decreased the overall area of the serous gland. However, acetylcholine had no effect on serous gland size. The effect of epinephrine on serous gland area was partially blocked by the adrenergic antagonist phenoxybenzamine. Measurement of individual lobes and whole breeding glands after 30 minutes of treatment (with epinephrine, norepinephrine, and acetylcholine) showed no significant change in area or perimeter. This experiment confirmed earlier studies demonstrating that adrenergic and not cholinergic stimulation can affect the secretion of serous glands in frogs. However, specific antagonists can mask these effects. In contrast, breeding gland secretion showed no variation in overall area or individual lobe size. Thus, breeding gland secretion is not regulated by adrenergic or cholinergic systems.

Metamorphosis may be defined as postembryonic developmental changes in non-reproductive structures of an organism. Such changes anticipate changes in the organism's environment (Frieden, 1961). Metamorphosis of amphibian larvae is dependent on the thyroid hormone in the circulating body fluid, and the normal sequence of metamorphosis has been correlated with a progressive increase in the concentration of thyroxine in the blood (Barch, 1953; Moore, 1964). While the rate of oxygen uptake in developing tadpoles has been well studied and documented, only a single reference on carbon dioxide release could be found. Belehradek and Huxley (1927) noted that carbon dioxide output increased immediately after the feeding of thyroid to frog tadpoles, but that during the ensuing induced metamorphosis, the carbon dioxide production diminished, finally reaching 60% of the original larval value. No references on carbon dioxide release during spontaneous metamorphosis could be found. In normal, aerobic respiration, the relative amounts of oxygen consumed and carbon dioxide released changed characteristically with the chemical nature of the metabolized substrate. An RQ of 1.0, 0.8, and 0.7 indicate metabolism of pure carbohydrate, lipid, and protein, respectively. Thus, the RQ provides some information about the nature of the transformations in progress (Witschi, 1956; Brown, 1964). The dietary change from herbivore to carnivore which occurs toward the end of anuran metamorphosis would be expected to result in a change in the ratio of oxygen consumed to CO2 produced. This study was undertaken with the intention of gaining an insight into the nature of the metabolic reactions in metamorphosing Hyla regilla tadpoles by determining the RQ at various stages of development.

Observations and collections on the breeding biology and life history of Rana pretiosa pretiosa Baird and Girard have been made in central Utah from 1962 to 1967. The frogs' activities were followed from their spring emergence untril the tadpoles metamorphosed and hibernated in the fall. Collections and observations were made at regular intervals through the entire period of summer activity. Data were gathered at the ponds and samples of the life history stages were taken to the laboratory where they were analyzed and studied. Emergence is normally during the middle of March. The males precede the larger females by three or four days. Immature frogs emerge approximately two weeks later. In Utah this species prefers small ponds of standing water grown thick with stonewort, Chara sp., and possessing a deep muck bottom from which cattails emerge. The males congregate in small areas of the pond as breeding choruses where they outnumber the females five to one. The male's call is weak and can be heard for approximately 6 to 10 meters. The eggs are laid shortly after the arrival of the females and vary in number from 147 to 1160 per clutch, the average being approximately 750 per clutch. The average size of individual eggs are as follows: Egg 2.5 mm, inner gelatinous envelope 5.0 mm, and outer envelope 10.0 mm. Hatching requires about two weeks in nature and varies between 7 and 23 days, depending upon temperature. Several factors noted which affect the frog's growth and behavior are temperature, crowding, and dissolved minerals in the water. Metamorphosis required from 122 to 209 days following ovulation. Hibernation took place during the middle of October approximately to weeks after the first freezing temperatures.

No description available.

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Many animals interact with the air-water interface during locomotion. Such location either involves moving through the water's surface or moving atop the water surface. This dissertation aims to investigate both of these forms of locomotion in frogs. First we quantified the kinematics of skittering, jumping on top the water's surface without sinking, in two species of frog, Acris crepitans and Euphlyctis cyanophlyctis. We found that what was described as "skittering" locomotion in Acris crepitans is actually more akin to porpoising. A. crepitans begins and ends each jump during their interfacial behavior under the water surface. These frogs may be unable to perform true skittering locomotion due to not being able to retract their hindlimbs fast enough. E. cyanophlyctis, however, does stay above the water surface during this mode of locomotion. We found that Euphlyctis is highly maneuverable during skittering locomotion compared to other inertial based water-surface traversing animals. Not only can they turn up to 80° between subsequent jumps, they also perform this behavior in close proximity to each other without collision. Next, we investigated control mechanisms used by frogs when jumping from water. Prior research has identified frogs of the genus Euphlyctis as high jumpers. But previous studies only considered their maximal performance. Here, we investigated how these frogs modulate propulsive force in order to control their jump height. We linked the frog limb kinematics to the jump force by modeling the added mass produced by the foot's motion. / Doctor of Philosophy / There are many animals that move across or through the water's surface. Most of them are very small and light and can thus be supported by surface tension. Larger animals instead must produce the force needed to stay afloat by moving quickly. Previous research has looked at the physics involved in running on the water surface in basilisk lizards and grebes. However, the ability of frogs to jump on the water surface (a behavior known as "skittering") has never been studied. In this dissertation, we examine the water-surface traversal of two frog species, Acris crepitans and Euphlyctis spp., using high-speed videography. Unlike previous human observations in the literature, we found that Acris does not stay atop the water's surface during its jumping behavior and instead begins and ends each jump under the water. This is similar to porpoising in animals like dolphins. Euphlyctis, however, does stay above the water during this jumping behavior. We found that these frogs can turn sharply between jumps which has not been observed in any other large water-runners. Additionally, we studied the ability of Euphlyctis to jump high in the air starting from floating on the water surface. These frogs are interesting to study because they can jump unusually high compared to other species of similar size and shape. We found that when shown insects at different heights, these frogs can control their jump height and only jump as high as necessary. By tracking the frogs' limbs during jumping we investigated several possible ways these frogs controlled their jump height.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 221-235). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 221-235). Also available on the Internet.

No description available.

published_or_final_version / Zoology / Master / Master of Science