Browsing by Author "Shaw, Evelyn S."
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Item The duration of schooling among fish separated and those not separated by barriers. American Museum novitates ; no. 2373(New York, N.Y. : American Museum of Natural History, 1969) Shaw, Evelyn S."Experiments were carried out to determine whether or not the duration of schooling was equivalent among fish separated by barriers and those not separated by barriers. The barriers were either transparent or they partly occluded vision. The results showed that the time pairs of fish spent oriented parallel to one another when separated by barriers was significantly less than the time other pairs of fish spent oriented parallel when they were not separated by barriers"--P. 11-12.Item Evidence of sexual maturation in young adult shiner perch, Cymatogaster aggregata Gibbons (Perciformes, Embiotocidae). American Museum novitates ; no. 2479(New York, N.Y. : American Museum of Natural History, 1971) Shaw, Evelyn S."Examination of Cymatogaster aggregata collected in Bodega Bay, California revealed that many young males, 5.0 to 6.0 cm. in length, become sexually mature during the first summer after birth and that females, 4.0 to 5.0 cm. in length, receive spermatozoa that can be found in their ovaries. he males are not sexually mature at birth. Fertilization in the adults occurs during the summer; all females in the collection made in late October were found to harbor spermatozoa in their ovaries. The implications of these findings are discussd"--P. [1].Item Hybridization in two sympatric species of atherinid fishes, Menidia menidia (Linnaeus) and Menidia beryllina (Cope). American Museum novitates ; no. 1999(New York, N.Y. : American Museum of Natural History, 1960) Rubinoff, Ira.; Shaw, Evelyn S.Item Modifiability of schooling behavior in fishes : the role of early experience. American Museum novitates ; no. 2448(New York, N.Y. : American Museum of Natural History, 1971) Williams, Madelaine M.; Shaw, Evelyn S."More than one thousand Menidia menidia, a schooling fish, were reared from the embryonic stage to the schooling stage under two environmental conditions, namely, together in aquarium tanks and separately in styrofoam cups. Many individually reared fish, the isolates, were given a single exposure with age peers at some point during their development. A number of individually reared fish that had contact showed behavioral modifications when compared with the isolates that were not given such an experience. Schooling behavior was modified among the isolates. Withdrawal behavior, which normally decreases when the schooling tendency is established continued to be seen at a significantly high level during the schooling phase. A new behavior, named lateral turning, was observed. Apparently, as a consequence of the continued high withdrawal rate and the lateral turning, the schooling organization was different among the isolates when compared with the schooling organization of the fish reared together in aquarium tanks"--P. 18.Item The optomotor response of a forebrainless fish, Tilapia mossambica. American Museum novitates ; no. 2446(New York, N.Y. : American Museum of Natural History, 1971) Shaw, Evelyn S.; Sherman, Richard A. W."The forebrain was removed from Tilapia mossambica, a cichlid fish that shows schooling behavior. The fish was tested in an optomotor apparatus before and after forebrain ablation. After ablation, there were significant decrements in fish r.p.m. in relation to drum r.p.m. and in the ability of the fish to reverse direction when drum direction was reversed. The relevance of these findings to schooling is discussed"--P. 15.Item Oral incubation in Tilapia macrocephala. 1, Embryological studies. Bulletin of the AMNH ; v. 103, article 5(New York : [American Museum of Natural History], 1954) Shaw, Evelyn S.; Aronson, Lester R. (Lester Ralph), 1911-"Embryos of the mouthbreeding cichlid fish Tilapia macrocephala do not survive, extra-orally, in aquarium water taken from the tank in which the spawning occurred. Experiments were performed to determine the role of oral incubation in embryonic survival. The approach used was to find methods of raising the embryos extra-orally and to relate extra-oral survival with the factors of survival in the milieu of the oral cavity. To facilitate this study, a series of embryological stages were described and defined from fertilization to hatching. Certain of the more obvious microscopic changes were described in conjunction with the gross descriptions of the stages. The most effective experimental media were 40 per cent sea water and sterile aquarium water in which mean embryonic survival ranged between 80 and 85 per cent. The common factor found in these media was their capability of keeping the bacterial growth that killed the embryos to a minimum. The limited effectiveness of other experimental media, e.g., NaCl, artificial sea water, methylene blue, and lysozyme, was dependent on a balance between their toxic properties and their bactericidal (or bacteriostatic) properties. Fungus mycelia usually appeared on embryos raised extra-orally in aquarium water. However, it was demonstrated experimentally that the fungus was a secondary invader, since survival was high when embryos were raised in sterile aquarium water to which a fungus culture had been introduced. Conversely, no embryos survived when they were raised in sterile water to which a culture of bacteria had been introduced. The churning action of the mouth was found to be one of the survival factors in oral incubation. When embryos were placed in a small quantity of aquarium water in a mechanical shaker, survival rates were good. On the other hand, embryos that remained stationary while a large quantity of water flowed over them never survived. These experiments show that the slow mechanical churning of the embryos in the mouth is a factor in survival, whereas the quantity of water flowing over the embryos during respiration of the parent is not critical. The oral epithelium may secrete mucus which protects the embryos. However, experiments designed to test the protective nature of mucus were not conclusive. Special pharyngeal glands, described in this paper, may secrete a bactericidal agent. Similar glands were found in Tilapia ovalis and have been described in two other mouthbreeding cichlids, while we were unable to find them in two non-mouthbreeding species of the genus Tilapia"--P. 413.