Pure tone thresholds in nine species of marine teleosts

p. 179-239 : ill. ; 27 cm.Includes bibliographical references (p. 235-239)

Embryonic development in fish

p. 165-229 : ill. ; 27 cm.Thesis (Ph. D.)--New York University.Includes bibliographical references (p. 227-229)."One. Embryonic development of the viviparous poeciliid fish Platypoecilus maculatus may be conveniently divided into 26 stages for descriptive purposes. 2. The embryonic growth rate for P. maculatus is determined by comparison of morphological age (in terms of embryonic stage) with theoretical age (days after the birth of a previous brood). This comparison is based on a series of embryonic broods obtained by laparotomy at various times during the twenty-eight- to thirty-day reproductive cycle of this species. 3. A study of growth and organogenesis in P. maculatus reveals the following features: A. The concomitant regression of the extra-embryonic membranes and the yolk mass is accompanied by a drop in the slope of the growth curve. B. The initial formation of the extra-embryonic membranes takes place in a manner similar to that in the 'amniotes.' C. Cleavage, gastrulation, and neurulation follow a course basically similar to that of other teleosts. D. Blastopore closure occurs after tail bud formation. E. The notochord forms directly from endoderm by delamination. F. Pigment formation is evident first in the retina and subsequently in the choroid and meningeal coats. G. Kupffer's vesicle (post-anal gut) contributes to the development of the urinary bladder. H. The formation of the ventral aorta and aortic arches is described with regard to the reversal of blood flow in the ventral aorta and the change of position of the sinus venosus during yolk regression. 4. Comparisons with other species of Platypoecilus (P. variatus, couchianus, and xiphidium) reveal no significant differences in embryonic development. 5. Platypoecilus maculatus development, compared to that of Xiphophorus hellerii and Platypoecilus-Xiphophorus hybrids, shows the following differences: A. Initial pigment differentiation in Xiphophorus occurs one stage later than in Platypoecilus. The hybrids form pigment at the same stage as Platypoecilus or earlier. B. Over the same period of time, Xiphophorus embryos attain a larger size than Platypoecilus embryos. The growth rates of the hybrids all coincide with or exceed those of Xiphophorus. C. Caudal fin differentiation is one stage later in Xiphophorus than in Platypoecilus. However, all the hybrids form a caudal fin at the same rate as P. maculatus, and the F[subscript 1] X Platypoecilus backcross hybrid embryos exceed both parental species in this respect. 6. Sterility and embryonic anomalies are frequent among hybrid females. This is particularly true of F[subscript 1] females possessing the Sd (spotted dorsal fin) character, indicating a linkage of lethal factors with this pattern gene"--P. 226

Reproductive behavior in fish

p. 431-459, [8] p. of plates : ill. ; 28 cm.Includes bibliographical references (p. 458-459)

Sound in catfishes

30 p., 28 p. of plates : ill. ; 27 cm.Includes bibliographical references (p. 27-30)."The skeletal basis of the sound producing mechanism in the ariid catfishes Galeichthys felis and Bagre marinus consists of a thin shelf of bone which is firmly attached to the anterior dorsal wall of the swim bladder. This so-called 'elastic spring,' or 'Springfederapparat,' is formed from the parapophysis of the fourth vertebra. The anterior ramus of this parapophysis, herein named the 'Müllerian ramus' (after Johannes Müller who, in 1842, first described the structure), is the main vibrating element in sound production. The skulls and anterior vertebral complexes of Galeichthys and Bagre are figured and described, with comparisons with a non-sonic silurid form, Wallago. The 'protractor muscle' (so named by Bridge and Haddon in 1893) which activates the Müllerian ramus is a highly vascularized conical muscle, the origin of which is on the under side of the epiotic lamina and insertion on the Müllerian ramus. It is innervated by the dorsal branch of the occipital nerve. The relationship of this nerve to the cranial nerves of higher vertebrates is controversial, but it is probably homologous with the hypoglossal (XII). Stimulation of the protractor muscle or its nerve supply with repetitive spike-form potentials results in an audible sound output from the Springfederapparat. This response can be recorded and analyzed, and its fundamental pitch is equivalent to the pulse frequency of the stimulus. The protractor muscle is remarkable in that it can withstand stimulations of 300 or more pulses per second without going into immediate tetany. In Bagre, the frequency response of the sonic system is about an octave higher than that in Galeichthys. Spontaneous sounds from these species consist of low-pitched grunts (fundamental pitch of about 150 cycles per second) and, in Bagre, higher, sob-like sounds (400 cycles per second or over). The harmonic components of both artificially induced and spontaneous sounds can be influenced by the amount of sound reflectance in the external environment. Even under partially anechoic conditions, the sound output is virtually a pure tone. Damage to the swim bladder reduces the amplitude of the sound but not its timbre (i.e., harmonic content). It was concluded that the swim bladder does not serve as a resonating chamber for these sounds, nor is it a true amplifier. Rather, it transfers the energy from the small area of the vibrating Müllerian ramus to the larger area of its entire outer surface, thus making the propagation of the sound from its source to the water more efficient. In acoustical and electronic terms, the swim bladder is an impedance matching device"--P. 27