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Eye-Lens Weight of the Bullfrog (Rana Catesbeiana) Related to Larval Development, Transformation, and Age of Adults
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bruggers, Richard L. Jackson, William Barry |
| Copyright Year | 1974 |
| Abstract | Eye-lens growth in larval, transforming, and adult bullfrogs was recorded, and the use of the lens-weight to age adults was examined. Over 500 animals in different developmental stages were captured from ponds in Wood County, Ohio. Using standard techniques, the lenses were removed, fixed, dried, and weighed. The animals also were weighed, measured, and internally sexed. Lens-weight in conjunction with developmental stage allowed separation of cohort populations (those animals from different spawning periods). Adults collected immediately after spring emergence, whose age had been estimated by the pterygoid-bone-ageing method, could be separated into annual classes. The eye-lens weight increased with age, although the rate of increase varied with the developmental stage of the animal. Mean lens-weights were significantly different for each developmental stage in the bullfrog life history, yet considerable overlap and individual variation occurred. The eye-lens growth of poorly-fed laboratory animals continued at a rate similar to that of animals in the wild. The purposes of this study were 1) to determine the eye-lens growth pattern throughout the developmental stages of the bullfrog, 2) to evaluate the eye-lens weight as a criterion of separating tadpoles of cohort populations and adult annual classes, and 3) to determine the influence of underfeeding on eye-lens growth. Since its introduction by Lord (1959), the use of the eye-lens weight to age animals has been tested by many investigators on a variety of mammals and birds. The lens-weight ageing technique has been more successful in mammals than birds, presumably due to the initial rapid growth in birds (Friend, 1967a). However, the method generally has permitted reliable ageing in early life: separation of individuals of initial "litters from those of subsequent litters, juveniles from adults, and annual classes. The technique has had limited application to poikilothermic animals. It was used successfully by Carlton and Jackson (1968) and Burkett and Jackson (1971) to separate annual age-groups of carp and freshwater drum, respectively, but unsuccessfully by Schroeder and Baskett (1968) to separate annual age-classes in summer-collected bullfrogs. MATERIALS AND METHODS Bullfrog tadpoles and adults were collected from July, 1970 to June, 1971 (except between December and March) from ponds in the Bowling Green State University's Steidtmann Wildlife Sanctuary and nearby Portage River, Wood County, Ohio (located seven miles south of Bowling Green, at 83°39'20"W longitude and 41°18'20"N latitude). Additional adults were collected immediately after spring emergence in March and April, 1972 from the Sanctuary and aged using the pterygoid-bone method (Schroeder and Baskett, 1968). The total number of animals caught each month usually exceeded 50. Immediately following collection, animals were etherized and fixed in 10% formalin from one to four weeks, a time interval found by Friend (1967b) to have little effect on the lens weight of rats. Both lenses were removed, oven dried for 48 hours at 120°C, and weighed to the nearest 0.01 mg, (with those less than 0.1 mg not recorded). To determine the effects of insufficient food on the growth of the lens, tadpoles from two collections (October, 1970 and April, 1971) were kept for two to four weeks under laboratory conditions of 21°C air and water temperatures and constant light (Bruggers, 1971). A small amount of Elodea was added to the twenty-gallon aquarium at the onset of each experimental period. It was not replaced as consumed, resulting in a condition of underfeeding. The laboratory animals were sacrificed on or near the date of a wild collection. All animals were weighed (wet weight, prior to lens removal) to the nearest 0.01 gram, and standard measurements recorded: body length, foreleg length, and hind leg length for 'Manuscript received September 4, 1973 (73-65). THE OHIO JOURNAL OF SCIENCE 74(5): 282, September, 1974 No. 5 BULLFROG AGEING WITH EYE-LENS WEIGHTS 283 adults and body, total length, hind and front leg length (when present) for tadpoles. The animals were separated into four developmental groups: A) tadpoles, B) tadpoles with hind legs, C) tadpoles with forelegs and tail (metamorphosing tadpoles), and D) frogs (which were further separated into those with body lengths less than the greater than 10 cm). RESULTS AND DISCUSSION General growth and development. The eye-lens weight increased with age, although the rate of increase varied with the developmental stage of the animals, being greatest at the time of metamorphosis (fig. 1). The rate of lens growth was |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://kb.osu.edu/bitstream/handle/1811/22236/V074N5_282.pdf?isAllowed=y&sequence=1 |
| Alternate Webpage(s) | http://kb.osu.edu/dspace/bitstream/handle/1811/22236/V074N5_282.pdf;jsessionid=8BF9014B682D0DAC8612636781A184F8?sequence=1 |
| Alternate Webpage(s) | http://kb.osu.edu/dspace/bitstream/handle/1811/22236/V074N5_282.pdf;jsessionid=4A40931FA8D59C4BE5AAC1D61947605B?sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
