Effects of seawater temperature on sound characteristics in Ophidion rochei (Ophidiidae)

Although the sound production mechanisms of male and female Ophidion rochei (Ophidiidae) differ significantly, temperature affects them in the same manner. In both sexes, temperature correlated negatively with pulse period and positively with sound frequencies but had no, or weak effects on other sound characteristics.     

Functional morphology of the sonic apparatus in Ophidion barbatum (Teleostei, Ophidiidae)

Most soniferous fishes producing sounds with their swimbladder utilize relatively simple mechanisms: contraction and relaxation of a unique pair of sonic muscles cause rapid movements of the swimbladder resulting in sound production. Here we describe the sonic mechanism for Ophidion barbatum, which includes three pairs of sonic muscles, highly transformed vertebral centra and ribs, a neural arch that pivots and a swimbladder whose anterior end is modified into a bony structure, the rocker bone. The ventral and intermediate muscles cause the rocker bone to swivel inward, compressing the swimbladder, and this action is antagonized by the dorsal muscle. Unlike other sonic systems in which the muscle contraction rate determines sound fundamental frequency, we hypothesize that slow contraction of these antagonistic muscles produces a series of cycles of swimbladder vibration.     

Functional morphology of the sonic apparatus in the fawn cusk-eel Lepophidium profundorum (Gill, 1863)

Recent reports of high frequency sound production by cusk-eels cannot be explained adequately by known mechanisms, i.e., a forced response driven by fast sonic muscles on the swimbladder. Time to complete a contraction-relaxation cycle places a ceiling on frequency and is unlikely to explain sounds with dominant frequencies above 1 kHz. We investigated sonic morphology in the fawn cusk-eel Lepophidium profundorum to determine morphology potentially associated with high frequency sound production and quantified development and sexual dimorphism of sonic structures. Unlike other sonic systems in fishes in which muscle relaxation is caused by internal pressure or swimbladder elasticity, this system utilizes antagonistic pairs of muscles: ventral and intermediate muscles pull the winglike process and swimbladder forward and pivot the neural arch (neural rocker) above the first vertebra backward. This action stretches a fenestra in the swimbladder wall and imparts strain energy to epineural ribs, tendons and ligaments connected to the anterior swimbladder. Relatively short antagonistic dorsal and dorsomedial muscles pull on the neural rocker, releasing strain energy, and use a lever advantage to restore the winglike process and swimbladder to their resting position. Sonic components grow isometrically and are typically larger in males although the tiny intermediate muscles are larger in females. Although external morphology is relatively conservative in ophidiids, sonic morphology is extremely variable within the family.     

The barbel‐like specialization of the pelvic fins in Ophidion rochei (Ophidiidae)

Pelvic fins in Ophidion rochei are reduced to four rod‐like structures situated at the ventral jaws. While the fish is swimming, they make continuous sweeping movements on the bottom. This paper examines and describes the anatomy of the pelvic fins to determine the possible functions of these appendages in relation to the mode of life of this fish species. The pelvic fins of O. rochei show strong similarities with barbels because they have identical sensory cell types, (taste buds, solitary chemosensory cells, and goblet cells), innervations and sensory function. Having nocturnal habits, specialization of pelvic fins in O. rochei corresponds to a supporting role to the life in dark environment. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Sexual dimorphism of sonic apparatus and extreme intersexual variation of sounds in <Emphasis Type="Italic">Ophidion rochei</Emphasis> (Ophidiidae): first evidence of a tight relationship between morphology and sound characteristics in Ophidiidae

Background

Many Ophidiidae are active in dark environments and display complex sonic apparatus morphologies. However, sound recordings are scarce and little is known about acoustic communication in this family. This paper focuses on Ophidion rochei which is known to display an important sexual dimorphism in swimbladder and anterior skeleton. The aims of this study were to compare the sound producing morphology, and the resulting sounds in juveniles, females and males of O. rochei.

Results

Males, females, and juveniles possessed different morphotypes. Females and juveniles contrasted with males because they possessed dramatic differences in morphology of their sonic muscles, swimbladder, supraoccipital crest, and first vertebrae and associated ribs. Further, they lacked the ‘rocker bone’ typically found in males. Sounds from each morphotype were highly divergent. Males generally produced non harmonic, multiple-pulsed sounds that lasted for several seconds (3.5?±?1.3 s) with a pulse period of ca. 100 ms. Juvenile and female sounds were recorded for the first time in ophidiids. Female sounds were harmonic, had shorter pulse period (±3.7 ms), and never exceeded a few dozen milliseconds (18?±?11 ms). Moreover, unlike male sounds, female sounds did not have alternating long and short pulse periods. Juvenile sounds were weaker but appear to be similar to female sounds.

Conclusions

Although it is not possible to distinguish externally male from female in O. rochei, they show a sonic apparatus and sounds that are dramatically different. This difference is likely due to their nocturnal habits that may have favored the evolution of internal secondary sexual characters that help to distinguish males from females and that could facilitate mate choice by females. Moreover, the comparison of different morphotypes in this study shows that these morphological differences result from a peramorphosis that takes place during the development of the gonads.

     

Semicystic spermatogenesis and reproductive strategy in Ophidion barbatum (Pisces, Ophidiidae)

In this paper the testicular structure and spermatogenesis of Ophidion barbatum are studied and the reproductive strategy of this species is analysed. The species has a rare type of spermatogenesis, called semicystic, in which the cyst ruptures in a stage prior to the spermatozoon stage. The most peculiar feature of the spermatozoon is its elongated shape, not typical of an oviparous species. Taking into account our results, the type of ovary and the spawning method, this species shows specialized characteristics which are fairly uncommon among oviparous species. The analysis of other biological aspects of the species, such as the capacity of the males to produce sounds, the low population density, the habit of individual members of burying themselves and the crepuscular habits, combined with our observations concerning their reproductive strategies, lead us to suggest a unique mating behaviour.     

Ontogeny of form and function: locomotor morphology and drag in zebrafish (Danio rerio)

Many fish species transform in body shape during growth, but it remains unclear how this influences the mechanics of locomotion. Therefore, the present study focused on understanding how drag generation during coasting is affected by ontogenetic changes in the morphology of zebrafish (Danio rerio). The shapes of the body and fins were measured from photographs of fish ranging in size from small larvae to mature adults and these morphometrics were compared to drag coefficients calculated from high-speed video recordings of routine swimming. We found that the viscous drag coefficient of larval and juvenile fish increased by more than an order of magnitude during growth and the inertial drag coefficient decreased at a comparable rate in adults. These hydrodynamic changes occurred as zebrafish disproportionately increased the span of their fins and their body changed shape from elongated to streamlined, as reflected by the logistic growth of a newly defined streamlining index, SL. These results suggest that morphological changes incur a performance cost by generating greater drag when larvae and juveniles operate in the viscous regime, but later provide a performance benefit by reducing pressure drag in the inertial regime of the adult stage.     

Interspecific variation of acoustic signals in Mediterranean gobies (Perciformes, Gobiidae): comparative analysis and evolutionary outlook

Sound production of 11 Mediterranean goby species, belonging to five different genera, have been comparatively analysed on the basis of the quantitative properties of the acoustic signal emitted by the male in both the reproductive and aggressive context. The results obtained showed that three groups of species can be recognized on the basis of signal similarity: the larger sized species (genus Padogobius and Gobius paganellus ) producing tonal sounds, showing high values of pulse rate and low values of duration; the larger-sized species producing grunt sounds (genus Gobius and Zosterisessor ) with low pulse rate and low duration; and the small-sized species producing grunt sounds (genus Pomatoschistus and Knipowitschia ) with low pulse rate and high duration. The comparison between these results and those found in previous studies suggests congruence between the acoustic affinities among species and that obtained by means of morphological and genetic data. Furthermore, first hypotheses on the evolution of acoustic communication and the associated mechanisms in this fish group are suggested.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 763–778.     

Allometric and morphological characteristics of Tonicella marmorea (Fabricius, 1780) populations (Mollusca: Polyplacophora: Ischnochitonidae)

Allometric and morphological characteristics of population samples of Tonicella marmorea from three sea lochs on the west coast of Scotland are described. The suitability of allometric relationships as taxonomic criteria are investigated by statistical comparisons of various regression constants, scatter diagrams and comparisons of curvature indices. Morphological characteristics such as ctenidia number and numbers of notches in the head and tail valves proved too variable to be regarded as diagnostic but they are useful taxonomic indicators. The need for all taxonomic characteristics to be derived from population samples is stressed and the use of valve and girdle sculpturing together with radula structure is emphasized.     

Growth of organ systems of Dentex dentex(L) and Psetta maxima(L) during larval development

Growth in volume of common dentex Dentex dentex and turbot Psetta maxima during larval development was studied by means of a quantitative histological method. A two‐phase pattern of volume increase was recorded for both species, turbot volume being always higher than dentex volume. During the first phase, the increase was small but during the second phase volume rose sharply from 22 days post hatch (dph) and 17 dph onwards in dentex and turbot, respectively. In dentex, the specific growth rate ( G ) of the whole larva as well as that of all the structures studied (nervous tissue, trunk musculature, digestive tract, liver, pancreas, spleen and thymus) was always higher during the second phase, whereas in turbot, only total volume of the larva, trunk musculature and nervous tissue had a higher G during the same period. The pattern of allometric growth of digestive organs was similar for both species. These organs showed an initial positive allometric growth that later became near‐isometric (digestive tract and liver) or negative (pancreas). In dentex, nervous tissue and trunk musculature showed near‐isometry throughout the period studied. In turbot, nervous tissue exhibited negative allometry and trunk musculature changed from negative to positive allometry. In both species studied, the highest allometry coefficients were recorded for digestive organs before the larva switched to strict exotrophy. This would indicate the importance of the development of these organs for survival.     

Skeletal and muscular pelvic morphology of hillstream loaches (Cypriniformes: Balitoridae)

The rheophilic hillstream loaches (Balitoridae) of South and Southeast Asia possess a range of pelvic girdle morphologies, which may be attributed to adaptations for locomotion against rapidly flowing water. Specifically, the connectivity of the pelvic plate (basipterygium) to the vertebral column via a sacral rib, and the relative size and shape of the sacral rib, fall within a spectrum of three discrete morphotypes: long, narrow rib that meets the basipterygium; thicker, slightly curved rib meeting the basipterygium; and robust crested rib interlocking with the basipterygium. Species in this third category with more robust sacral rib connections between the basipterygium and vertebral column are capable of walking out of water with a tetrapod-like lateral-sequence, diagonal-couplet gait. This behavior has not been observed in species lacking direct skeletal connection between the vertebrae and the pelvis. The phylogenetic positions of the morphotypes were visualized by matching the morphological features onto a novel hypothesis of relationships for the family Balitoridae. The morphotypes determined through skeletal morphology were correlated with patterns observed in the pelvic muscle morphology of these fishes. Transitions towards increasingly robust pelvic girdle attachment were coincident with a more anterior origin on the basipterygium and more lateral insertion of the muscles on the fin rays, along with a reduction of the superficial abductors and adductors with more posterior insertions. These modifications are expected to provide a mechanical advantage for generating force against the ground. Inclusion of the enigmatic cave-adapted balitorid Cryptotora thamicola into the most data-rich balitorid phylogeny reveals its closest relatives, providing insight into the origin of the skeletal connection between the axial skeleton and basipterygium.     

Traffic noise differentially impacts call types in a Japanese treefrog (Buergeria japonica)

Acoustic noise from automobile traffic impedes communication between signaling animals. To overcome the acoustic interference imposed by anthropogenic noise, species across taxa adjust their signaling behavior to increase signal saliency. As most of the spectral energy of anthropogenic noise is concentrated at low acoustic frequencies, species with lower frequency signals are expected to be more affected. Thus, species with low-frequency signals are under stronger pressure to adjust their signaling behaviors to avoid auditory masking than species with higher frequency signals. Similarly, for a species with multiple types of signals that differ in spectral characteristics, different signal types are expected to be differentially masked. We investigate how the different call types of a Japanese stream breeding treefrog (Buergeria japonica) are affected by automobile traffic noise. Male B. japonica produce two call types that differ in their spectral elements, a Type I call with lower dominant frequency and a Type II call with higher dominant frequency. In response to acoustic playbacks of traffic noise, B. japonica reduced the duration of their Type I calls, but not Type II calls. In addition, B. japonica increased the call effort of their Type I calls and decreased the call effort of their Type II calls. This result contrasts with prior studies in other taxa, which suggest that signalers may switch to higher frequency signal types in response to traffic noise. Furthermore, the increase in Type I call effort was only a short-term response to noise, while reduced Type II call effort persisted after the playbacks had ended. Overall, such differential effects on signal types suggest that some social functions will be disrupted more than others. By considering the effects of anthropogenic noise across multiple signal types, these results provide a more in-depth understanding of the behavioral impacts of anthropogenic noise within a species.     

Macro- and microscopic morphology of the flank scales of families Lutjanidae and Serranidae from the Persian Gulf Coral Reefs (Teleosts: Perciformes)

Macro- and microscopic characteristics of flank scales for 12 species were investigated from the Persian Gulf Coral Reefs. In Lutjanus argentimaculatus and L. russellii (family Lutjanidae), the scales of different flank regions were not different, while four characters showed variation in the scale of L. lutjanus i.e., scale shape (pentagonal, hexagonal and square), anterior margin (waved, scalloped and smooth), focus shape (circular and oblong) and focus position (postero-central and central), displayed variation. Scale type (ctenoid) and posterior margin (transforming ctenii) did not show variation and could be considered to be specific in this family. In Epinephelus chlorostigma (family Serranidae), the scales of flank regions did not display variation, while in E. areolatus, E. diacanthus and E. radiates, the scales showed considerable variation. The most variable characters were scale shape, posterior margin and focus shape. Therefore, in fish systematics studies on the base of scale, it is particularly important to compare scales from the same flank regions. Also, some criteria such as size-dependent alternation, ontogenetic changes and variation between flank regions, should be considered. This study supports the potential of scale morphology to help for the understanding of fish diversity in the coral reef ecosystem.     

Dominant frequency of loud mew calls of felids (Mammalia: Carnivora) decreases during ontogenetic growth

• 1 A negative correlation between body weight and frequency characteristics of a species' vocalizations exists in mammals, due to the acoustics of vocal sound production (‘source‐filter theory’; source = larynx; filter = supralaryngeal vocal tract) and the strong positive correlation between body weight and vocal tract length.
• 2 A negative correlation is hypothesized to exist between increasing body weight and frequency characteristics of calls during ontogeny as well.
• 3 This hypothesis is tested for mean dominant frequency (maximum spectral energy peak) of intense mew calls in juveniles of five species of the Felidae: lion Panthera leo, jaguar Panthera onca, leopard Panthera pardus, tiger Panthera tigris and puma Puma concolor.
• 4 In the five felid species in which the hyoid is incompletely ossified (genera Panthera and Uncia), the larynx undergoes a considerable ontogenetic descent, resulting in a proportionally longer vocal tract in adult individuals than in all other species of the family, which have a fully ossified hyoid without a descent.
• 5 In all five species studied here, mean dominant frequency decreases as body weight increases during growth. In the four Panthera species (with laryngeal descent) dominant frequency is determined by the vocal tract (the filter), and dominant frequency is largely similar at similar weights, indicating a similar correlation between the ontogenetic increase in body weight (and vocal tract length) and the decrease in mean dominant frequency. In the puma (without laryngeal descent) dominant frequency is determined by the larynx (the source), it is considerably higher than in the Panthera species, and the course of its ontogenetic decrease differs considerably from that in Panthera.
• 6 The data do not support a uniform scaling relationship between body weight and mean dominant frequency of intense mew calls in the Felidae during ontogenetic growth.

     

Functional morphology of the feeding apparatus of the nymph of Farrodes sp. (Ephemeroptera: Leptophlebiidae)

Farrodes nymphs are specialized periphyton/biofilm scrapers. Their maxillae are the most specialized mouthparts, but other elements, with their systems of variously modified setae, are designed to obtain and transport food particles to the pharynx with a minimum of loss. The morphology and adaptations of these mouthparts and related head areas, as well as associated musculature, are described.     

Semen characteristics and sperm morphology of serow (Capricornis sumatraensis)

The serow (Capricornis sumatraensis) is a critically endangered species. The objectives of this study were to evaluate ejaculate quality in captive males, and to investigate and characterize sperm morphology. Semen was collected using electroejaculation. Mean (±S.D.) seminal characteristics were: semen volume 2.3 ± 0.8 mL, pH 7.8 ± 0.4, and osmolality 329.9 ± 32.9 mOsmol/kg; sperm concentration 515.8 ± 263.1 × 10⁶ cells/mL; wave motion score (1-5) 3.9 ± 0.4; motile sperm 60.5 ± 22%; viable sperm 68.3 ± 9.4%; morphologically normal sperm 70.8 ± 19.3%; and an opacity that was yellowish to milky-white. Sperm head length, width, degree of elongation, area, and perimeter were 6.0 ± 0.6 μm, 4.3 ± 0.3 μm, 71.7 ± 8.6%, 19.8 ± 2.5 μm², and 17.9 ± 2.1 μm. Based on these measurements, we categorized sperm head morphometry as small, medium, or large. In addition, sperm morphology was examined by light and scanning electron microscopy; overall, morphologically normal and abnormal sperm were similar to those reported for other bovidae. In summary, this study provided baseline data regarding semen characteristics of C. sumatraensis, which should be of value in the preservation of this endangered species.     

Morphological characteristics of the Pterodoras granulosus digestive tube (Valenciennes, 1821) (Osteichthyes,Doradidae)

Little is known about the digestive tube (DT) morphology of the fish Pterodoras granulosus. Therefore, macro‐, meso‐ and microscopic aspects of 15 P. granulosus DTs were analysed. The muscular layer was composed of striated skeletal muscle in the oesophagus and smooth muscle in the other segments. The epithelium progressed from a stratified pavement in the oesophagus to a simple column in the other segments, with a flat striated border in the intestine. A large number of mucus‐secreting periodic acid‐Schiff (PAS)‐positive cells were observed in the oesophagus. In the stomach, the number of glands in the region decreased towards the cardiac–fundic region, and none were found in the pylorus. The intestine showed an epithelium with absorption cells and an increasing number of PAS‐positive caliciform cells towards the distal region. Tests showed that the oesophagus is adapted for passing and preparing food for the chemical digestion that occurs in the stomach, which also has storage functions without grinding action. The proximal intestinal region was consistent with fat absorption, and the medium region, with the absorption of other nutrients. The distal region was short and consistent with a role in absorption for osmoregulation as well as in the formation, storage and disposal of faeces.     

Scale effects and constraints for sound production in katydids (Orthoptera: Tettigoniidae): correlated evolution between morphology and signal parameters

Male katydids (Orthoptera: Tettigoniidae) produce mating calls by rubbing the wings together, using specialized structures in their forewings (stridulatory file, scraper and mirror). A large proportion of species (ca. 66%) reported in the literature produces ultrasonic signals as principal output. Relationships among body size, generator structures and the acoustic parameters carrier frequency (f_c) and pulse duration (p_d), were studied in 58 tropical species that use pure‐tone signals. A comparative analysis, based on the only available katydid phylogeny, shows how changes in sound generator form are related to changes in f_c and p_d. Anatomical changes of the sound generator that might have been selected via f_c and p_d are mirror size, file length and number of file teeth. Selection for structures of the stridulatory apparatus that enhance wing mechanics via file‐teeth and scraper morphology was crucial in the evolution of ultrasonic signals in the family Tettigoniidae.     

Evolution of multivariate wing allometry in schizophoran flies (Diptera: Schizophora)

The proximate and ultimate mechanisms underlying scaling relationships as well as their evolutionary consequences remain an enigmatic issue in evolutionary biology. Here, I investigate the evolution of wing allometries in the Schizophora, a group of higher Diptera that radiated about 65 million years ago, by studying static allometries in five species using multivariate approaches. Despite the vast ecological diversity observed in contemporary members of the Schizophora and independent evolutionary histories throughout most of the Cenozoic, size‐related changes represent a major contributor to overall variation in wing shape, both within and among species. Static allometries differ between species and sexes, yet multivariate allometries are correlated across species, suggesting a shared developmental programme underlying size‐dependent phenotypic plasticity. Static allometries within species also correlate with evolutionary divergence across 33 different families (belonging to 11 of 13 superfamilies) of the Schizophora. This again points towards a general developmental, genetic or evolutionary mechanism that canalizes or maintains the covariation between shape and size in spite of rapid ecological and morphological diversification during the Cenozoic. I discuss the putative roles of developmental constraints and natural selection in the evolution of wing allometry in the Schizophora.