A preliminary study of development of the buccal apparatus in Pomacentridae (Teleostei, Perciformes)

This study compares, in five species of Pomacentridae (Chromis viridis, Dascyllus flavicaudus, Chrysiptera glauca, Pomacentrus pavo, Plectroglyphidodon lacrymatus), the changes in cephalic skeletal structures between settling larvae and adults living on the reef. Variations were studied in the suspensorium, the opercle, the mandible, the premaxillary bone and the teeth. Comparisons of the feeding apparatus enabled two different types of feeding to be distinguished in adults: suction feeding and grazer sucking. Adult C. viridis and D. flavicaudus have a high suspensorium, a well-rounded mouth during jaw opening and caniniform teeth. These two species can be considered to be suction feeders. On the other hand, adult C glauca, P pavo and P lacrymatus have less developed suspensoria, opercles and ascending process of the premaxillar, and present incisiform teeth. These three species appear to be grazer suckers. However, the larvae of all five species present an unimodal way of feeding, defined as ram-suction. Differences between larvae and adults appear clearly to be related to their ecology. The increasing variation presented in feeding apparatus during the settlement phase could be linked to diversification leading to occupancy of different ecological niches.Peer reviewe

Relationships between inner ear and sagitta growth during ontogenesis of three Carapini species, and consequences of life-history events on the otolith microstructure

Three species of Carapidae have in common a tenuis larval stage, during which they settle in the lagoon and take refuge in the same species of holothurold. From the juvenile stage, Carapus homei and C. boraborensis are commensal, whereas Encheliophis gracilis is parasitic. The aims of this study were to analyse to what extent the ontogenctic changes of the otic capsule affected the shape of the inner ear and how environmental cues, due to the above-mentioned life history and the style, could influence the structure of the sagitta. Sagittal sections revealed a three-dimensional asymmetry with a nucleus close to the proximal surface. Observations of the growth axis of the sagitta suggest it has a morphogenetic impact on the otic cavity. Each sagitta contains three main zones related to the life stages of the fish. Bands and checks were observed in the third zone in C. homei and C. boraborensis, but this pattern was less discernible in E. gracilis. These structural differences in zone 3 could be related to the commensal and parasitic life styles of these fishes. Further studies dealing with otosac features and otolith functions are suggested.Peer reviewe

Trophic niches of thirteen damselfishes (Pomacentridae) at the Grand Récif of Toliara, Madagascar

The damselfishes, with more than 340 species, constitute one of the most important families that live in the coral reef environment. Most of our knowledge of reef-fish ecology is based on this family, but their trophic ecology is poorly understood. The aim of the present study was to determine the trophic niches of 13 sympatric species of damselfishes by combining stable isotope (d15N and d13C) and stomach content analyses. Isotopic signatures reveal three main groups according to their foraging strategies: pelagic feeders (Abudefduf sexfasciatus, A. sparoides, A. vaigiensis, Chromis ternatensis, C. dimidiata, Dascyllus trimaculatus and Pomacentrus caeruleus), benthic feeders (Chrysiptera unimaculata, Plectroglyphidodon lacrymatus and Amphiprion akallopisos) and an intermediate group (D. aruanus, P. baenschi and P. trilineatus). Stomach contents reveal that planktonic copepods and filamentous algae mainly represent the diets of pelagic feeders and benthic feeders, respectively. The intermediate position of the third group resulted from a partitioning of small planktonic prey, small vagile invertebrates and filamentous algae. In this last feeding group, the presence of a wide range of d13C values in P. trilineatus suggests a larger trophic niche width, related to diet-switching over time. Some general considerations about the feeding habits of damselfishes reveal that their choice of habitat on the reef and their behavior appear to be good predictors of diet in this group. Benthic (algae and/or small invertebrates) feeders appear to be solitary and defend a small territory on the bottom; zooplankton feeders remain in groups just above the reef, in the water column.Peer reviewe

Interspecific variation of calls in clownfishes: degree of similarity in closely related species

Clownfishes are colorful coral reef fishes living in groups in association with sea anemones throughout the Indo-Pacific Ocean. Within their small societies, size hierarchy determines which fish have access to reproduction. These fishes are also prolific callers whose aggressive sounds seem to play an important role in the social hierarchy. Agonistic interactions being involved in daily behaviour suggest how acoustic communication might play an important role in clownfish group. Sounds were recorded and compared in fourteen clownfish species (some of which have never been recorded before) to evaluate the potential role of acoustic communication as an evolutionary driving force. Surprisingly, the relationship between fish size and both dominant frequency and pulse duration is not only species-specific; all the specimens of the 14 species are situated on exactly the same slope, which means the size of any Amphiprion can be predicted by both acoustic features. The number of pulses broadly overlaps among species, whereas the pulse period displays the most variation even if it shows overlap among sympatric species. Sound comparisons between three species (A. akallopisos, A. ocellaris and A. frenatus) having different types of teeth and body shape do not show differences neither in the acoustic waveform nor in the power spectrum. Significant overlap in acoustic features demonstrates that the sound-producing mechanism is highly conservative among species. Differences in the calls of some species are due to size dimorphism and the sound variation might be in this case a by-product. This morphological constraint does not permit a consideration of acoustic communication as the main driving force in the diversification of clownfishes. Moreover, calls are not produced to find mate and consequently are less subject to variations due to partner preference, which restricts the constraints of diversification. Calls are produced to reach and defend the competition to mate access. However, differences in the pulse period between cohabiting species show that, in some case, sounds can help to differentiate the species, to prevent competition between cohabiting species and to promote the diversification of taxa

Comparative study on sound production in different Holocentridae species

<p/> <p>Background</p> <p>Holocentrids (squirrelfish and soldierfish) are vocal reef fishes whose calls and sound-producing mechanisms have been studied in some species only. The present study aims to compare sound-producing mechanisms in different Holocentridae genera (<it>Holocentrus</it>, <it>Myripristis</it>, <it>Neoniphon</it>, <it>Sargocentron</it>) from separate regions and, in some cases, at different developmental stages. An accurate comparison was made by recording six species while being hand-held, by observing TEM) the sonic muscles and by dissections of the sound-producing mechanism.</p> <p>Results</p> <p>In all these species, calls presented harmonics, their dominant frequency was between 80 and 130 Hz and they were composed of trains of 4 to 11 pulses with gradual increasing periods towards the end of the call. In each case, the calls did not provide reliable information on fish size. The sounds were produced by homologous fast-contracting sonic muscles that insert on articulated ribs whose proximal heads are integrated into the swimbladder: each pulse is the result of the back and forth movements of the ribs. Small differences in the shape of the oscillograms of the different species could be related to the number of ribs that are involved in the sound-producing mechanism. These fish species are able to make sounds as soon as they settle on the reef, when they are 40 days old. Comparison between <it>Neoniphon </it>from Madagascar and from Rangiroa in French Polynesia showed a new, unexpected kind of dialect involving differences at the level of pulse distribution. <it>Neoniphon </it>calls were characterised by a single pulse that was isolated at the beginning of the remaining train in Madagascar whereas they did not show any isolated single pulses at the beginning of the call in Rangiroa.</p> <p>Conclusion</p> <p>This family cannot use the acoustic fundamental frequencies (or pulse periods) of grunts to infer the size of partners. Pulse duration and number of pulses are statistically related to fish size. However, these characteristics are poorly informative because the correlation slope values are weak. It remains other features (sound amplitude, resistance to muscle fatigue, calling frequency) could be used to assess the body size. Characteristics of the sound producing mechanisms are conservative. All species possess fast-contracting muscles and have the same kind of sound producing mechanism. They do show some change between clades but these differences are not important enough to deeply modify the waveforms of the calls. In this case, our description of the grunt could be considered as the signature for the holocentrid family and can be used in passive acoustic monitoring.</p

Відділення фізики і астрономії Національної академії наук України

Developmental changes in myofibrillar protein composition were investigated in the myotomal muscle of the African catfish, Heterobranchus longifilis (Clariidae), by several electrophoretic techniques. The main muscle fibres of larvae and the fast-white muscle fibres of juvenile and adult fish were found to express distinct myosin heavy chain and myosin light chain 2 (LC2) isoforms. Three myosin LC2 chains were successively detected, differing by their isoelectric points. In contrast, the alkali light chains remained qualitatively and quantitatively unchanged during fish growth. Actin, α-tropomyosin, and troponin-C (TN-C) were also similar in larval, juvenile, and adult white muscle, but an additional larval tropomyosin isoform was found in the first developmental stages. Two isoforms of troponin-T (TN-T) and troponin-I (TN-I) were synthesised in the course of fish growth. Transition from the larval to the adult isoform was much faster for TN-T than for TN-I. Slow-red muscle myofibrils from adult H. longifilis showed no common component (except actin) with larval, juvenile, or adult fast-white muscle myofibrils. Red myofibrils displayed a single TN-T and a single TN-I isoform, but two isoforms of TN-C. The myofibrillar protein isoforms synthesised at any given developmental stage almost certainly reflect changes in the functional requirements of swimming muscles in the course of fish development

Sound production in the clownfish Amphiprion clarkii

Although clownfish sounds were recorded as early as 1930, the mechanism of sound production has remained obscure. Yet, clownfish are prolific "singers" that produce a wide variety of sounds, described as "chirps" and "pops" in both reproductive and agonistic behavioral contexts. Here, we describe the sonic mechanism of the clownfish Amphiprion clarkii

荀卿的韻文

戰國年間，北方產生了一位値得稱說的作家，他的文學作品爲了他的哲學思想被人忽略的，那便是荀卿了。硏究中國上古哲學史的，沒有人抛棄了荀卿；製作中國上古文學史的，對於荀卿多付闕如。以取材宏博見稱的謝著中國大文學史及號稱編製完備的鄭著插圖本中國文學史而言，荀氏所佔的篇幅，爲了作者吝惜，都得不到半頁。在數行叙述中，又往往未談及文學的本身！我以爲這不僅是荀氏個人的損失，實是中國文畢史上的損失。現在我不量棉薄，關於荀氏的韻文作一次檢討