Taste buds on the lips and mouth of some blenniid and gobiid fishes: comparative distribution and morphology

Analysis of taste buds (TB) on the lips and oropharyngeal cavity in several species of gobies (Gobiidae) and blennies (Blenniidae) from the Red Sea, Mediterranean Sea and Seychelles, revealed three types of these organs: types I and II, which protrude above the surrounding epithelium on lobules of various forms, and type III, which terminate on the level of the epithelium. These TB are composed of either light or dark sensory cells with apical microvillar extensions, and of basal cells situated at the TB base. Synaptic junctions occur between the TB cells and the sub‐epithelial sensory nerves. Numerical distribution and morphology of TB on the lips and in the oral cavity of the species studied revealed patterns that are specific on both species and family levels. In most of the gobies the lips, jaws and oral breathing valves are usually covered by numerous lobules, each of which bears papillae with two to seven type I and type II TB, reaching a total of up to 7500 buds on the lips and in the oropharyngeal cavity in these fishes. The number of TB increases with growth (age) of the fish, and the combined and total sensory area of TB in an adult fish can reach up to 80 000 μm². In contrast, in blennies the anterior region of the oral cavity is seldom lobulated, with far fewer TB; the majority of TB are found in the more posterior region. It is postulated that these differences in TB density and location between gobies and blennies are connected to differences in foraging strategies and diet, and may represent ecomorphological adaptations.     

Comparison of the oropharyngeal cavity in the Starksiini (Teleostei: Blenniiformes: Labrisomidae): Taste buds and teeth,including a comparison with closely‐related genera

The present study describes the distribution of taste buds and teeth in the oropharyngeal cavity of 13 species of adult (18–60 mm SL) Starksiini fishes inhabiting subtidal waters of the Neotropical region. Four types of taste buds described previously in other fish groups were observed within the oropharyngeal cavity, of which type I, situated on prominent protruding papillae, is the most common. The number of taste buds in this cavity varies considerably, ranging from ca. 202 in Starksia lepicoelia to ca. 770 in S. sluiteri. In all the studied species, taste buds are more numerous on the posterior (160–396) than on the anterior (42–294) part of the oropharyngeal cavity. The presence of different numbers of taste buds in different Starksiini species of the same standard length suggests that numbers of taste buds are not directly correlated with size and may be species‐specific. Teeth are found on the premaxilla, dentary, vomer, palatine (in some species) and the upper and lower pharyngeal jaws (third pharyngobranchials and fifth ceratobranchials, respectively); the form and number of teeth and taste buds on each of these sites differs among the various species of Starksiini and between them and closely related species of the labrisomid tribes Labrisomini, Mnierpini, and Paraclinini. The results thus suggest potential systematic value in certain features of the oropharyngeal cavity for blenniiform fishes. It is also shown that benthic‐feeding omnivorous fishes have higher densities of taste buds than piscivorous fishes. A possible correlation among numbers of taste buds, their positions in the oropharyngeal cavity, and other parameters is discussed. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Mancae of the parasitic cymothoid isopod, <Emphasis Type="Italic">Anilocra apogonae</Emphasis>: early life history,host-specificity,and effect on growth and survival of preferred young cardinal fishes

Juvenile parasitic cymothoid isopods (mancae) can injure or kill fishes, yet few studies have investigated their biology. While the definitive host of the adult cymothoids is usually a single host from a particular fish species, mancae may use so-called optional intermediate hosts before settling on the definitive host. Little, however, is known about these early interactions. The cymothoid isopod, Anilocra apogonae, infests the definitive host, Cheilodipterus quinquelineatus. This study examined their host preference among potential optional intermediate hosts. Their effect on the growth and mortality of the young of three apogonid fishes, including the definitive host, was investigated. The number of mancae produced per brood was positively correlated with female length. When given a choice of intermediate hosts, significantly more mancae attached to Apogon trimaculatus (Apogonidae) than to Apogon nigrofasciatus. When presented with Ap. trimaculatus and Pomacentrus amboinensis (Pomacentridae), mancae only attached to Ap. trimaculatus suggesting that mancae may show a taxonomic affiliation with preferred hosts. Mancae fed on all three apogonid species, with C. quinquelineatus being fed on earlier than Ap. trimaculatus and Ap. nigrofasciatus. Mancae feeding frequency, adjusted for fish survival, was lowest on C. quinquelineatus and highest on Ap. trimaculatus. Infested apogonids had reduced growth and increased mortality compared with uninfested fish. A. apogonae mancae can use several species of young apogonid fishes as optional intermediate hosts. Via reduced growth and increased mortality, mancae have the potential to negatively influence definitive host populations and also other young species of apogonid fishes.     

The evolution of pharyngeal bones and teeth in Gobioninae fishes (Teleostei: Cyprinidae) analyzed with phylogenetic comparative methods

The subfamily Gobioninae is a subgroup in the specious fish family Cyprinidae, which bears high diversity in morphological and ecological dimensions and has its most components distributed in East Asia. In this study, the pharyngeal bones and teeth of 39 species belonging to 19 genera of the Gobioninae were examined, with the phylogenetic comparative method (PCM) and correlation methods employed to analyze the character evolution. Three characters on pharyngeal bones (shape of the pharyngeal bones, extension for attachment of the pharyngo-cleithralis internus posterior (PCIP) muscle, and teeth-bearing area) and six characters of pharyngeal teeth (shape of the five teeth in the main row, number of rows of the teeth) were identified and compared. When the character states were mapped on a molecular phylogenetic tree, it was found that, to adapt to different masticatory operations, different Gobioninae species have various morphological types of pharyngeal bones and teeth: some have intermediate pharyngeal bones bearing multiple rows of diverse teeth (conical, coarsely compressed, and compressed), others have broad pharyngeal bones bearing a single row of molar teeth, and still others have narrow pharyngeal bones bearing a single row of extremely compressed teeth. Tests on the phylogenetic signal and evolutionary associations revealed that evolution of the examined characters was all phylogenetically constrained and correlated. Owing to the homoplasy in evolution, it was suggested that the conventional method of using pharyngeal bones and teeth for phylogenetic reconstruction of cyprinid fishes should not be encouraged.     

Studies on the skull of the Indian sisorid catfish, Erethistes pussilus

The skull of Erethistes pussilus is described in detail. The general disposition of the bones corresponds to the siluroid pattern. Among the siluroid fishes, E. pussilus approaches the advanced forms in certain features such as obliteration of myodomic space, edentulous palate, absence of entopterygoids and supratemporals, intimate sutural articulation of posttemporals and complex vertebra with the cranium, diminished cranial cavity and loss of sutural articulation among the palatopterygoquadrate elements. In certain characters like the hyomandibula exclusively supported from the sphenotic, solitary hypohyal on each hyoid cornu, absence of interhyals, reduced orbits, edentulous vomer, small gape of mouth, toothless ectopterygoid and in the small number of branchiostegals, E. pussilus stands specialized alone among the catfishes. A diagnosis of the salient cranial characters of the fish is given and its relationship discussed.     

Studies on the skull of the Indian sisorid catfish, Erethistes pussilus

The skull of Erethistes pussilus is described in detail. The general disposition of the bones corresponds to the siluroid pattern. Among the siluroid fishes, E. pussilus approaches the advanced forms in certain features such as obliteration of myodomic space, edentulous palate, absence of entopterygoids and supratemporals, intimate sutural articulation of posttemporals and complex vertebra with the cranium, diminished cranial cavity and loss of sutural articulation among the palatopterygoquadrate elements. In certain characters like the hyomandibula exclusively supported from the sphenotic, solitary hypohyal on each hyoid cornu, absence of interhyals, reduced orbits, edentulous vomer, small gape of mouth, toothless ectopterygoid and in the small number of branchiostegals, E. pussilus stands specialized alone among the catfishes. A diagnosis of the salient cranial characters of the fish is given and its relationship discussed.     

Site fidelity and homing in tropical coral reef cardinalfish: are they using olfactory cues?

A number of tropical coral reef fish hold station and display restricted home ranges. If artificially displaced, they will return to their home site. We questioned if marine fish are using the same mechanisms for home site detection as many freshwater fish, that is, by olfactory sensing of chemical signals deposited on the substrate by conspecific fish. Behavioral experiments were conducted on Lizard Island Research Station, Queensland, Australia, in 2001 and 2002. Five-lined cardinalfish (Cheilodipterus quinquelineatus) were tested in groups with split-branded cardinalfish (Apogon compressus) as a reference species and individually against Apogon leptacanthus as well as conspecifics of another reef site. The group tests showed that both species preferred artificial reef sites that had previously been occupied by conspecifics. Individual C. quinquelineatus preferred scent of conspecifics from their own reef site to that from another site. They also preferred the scent released by artificial reefs previously occupied by conspecifics of their reef site to that of similar reefs previously occupied by conspecifics of another reef site. No discrimination between species from the same reef site was obtained in experiments with individual fish. Our data suggest that cardinalfish are keeping station and are homing by use of conspecific olfactory signals.     

Site fidelity and homing behaviour in coral reef cardinalfishes

Tagged adult cardinalfishes Apogon doederlini , Cheilodipterus artus and Cheilodipterus quinquilineatus persisted to within an average of 36–79 cm of their initial resting positions within One Tree Reef lagoon for over 8 months in A. doederlini and over 16 months in C. artus and C. quinquilineatus . In addition, 56–81% of tagged fish displaced c. 1 km, and 33–63% of tagged fish displaced c. 2 km returned to their point of collection within 3 days. As cardinalfishes are often found densely aggregated at resting sites, their extended use of specific sites on reefs may represent a localized, predictable resource for predators and a significant source of spatial variation in nutrient input to reef systems via faeces.     

(鱼句)亚科花(鱼骨)型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。     

An Ancient Gene Network Is Co-opted for Teeth on Old and New Jaws

Vertebrate dentitions originated in the posterior pharynx of jawless fishes more than half a billion years ago. As gnathostomes (jawed vertebrates) evolved, teeth developed on oral jaws and helped to establish the dominance of this lineage on land and in the sea. The advent of oral jaws was facilitated, in part, by absence of hox gene expression in the first, most anterior, pharyngeal arch. Much later in evolutionary time, teleost fishes evolved a novel toothed jaw in the pharynx, the location of the first vertebrate teeth. To examine the evolutionary modularity of dentitions, we asked whether oral and pharyngeal teeth develop using common or independent gene regulatory pathways. First, we showed that tooth number is correlated on oral and pharyngeal jaws across species of cichlid fishes from Lake Malawi (East Africa), suggestive of common regulatory mechanisms for tooth initiation. Surprisingly, we found that cichlid pharyngeal dentitions develop in a region of dense hox gene expression. Thus, regulation of tooth number is conserved, despite distinct developmental environments of oral and pharyngeal jaws; pharyngeal jaws occupy hox-positive, endodermal sites, and oral jaws develop in hox-negative regions with ectodermal cell contributions. Next, we studied the expression of a dental gene network for tooth initiation, most genes of which are similarly deployed across the two disparate jaw sites. This collection of genes includes members of the ectodysplasin pathway, eda and edar, expressed identically during the patterning of oral and pharyngeal teeth. Taken together, these data suggest that pharyngeal teeth of jawless vertebrates utilized an ancient gene network before the origin of oral jaws, oral teeth, and ectodermal appendages. The first vertebrate dentition likely appeared in a hox-positive, endodermal environment and expressed a genetic program including ectodysplasin pathway genes. This ancient regulatory circuit was co-opted and modified for teeth in oral jaws of the first jawed vertebrate, and subsequently deployed as jaws enveloped teeth on novel pharyngeal jaws. Our data highlight an amazing modularity of jaws and teeth as they coevolved during the history of vertebrates. We exploit this diversity to infer a core dental gene network, common to the first tooth and all of its descendants.     

Prey selection and functional morphology through ontogeny of Amphiprion clarkii with a congeneric comparison

The relationship between the complexity of the feeding apparatus and prey selection through ontogeny was examined in Amphiprion clarkii larvae. Larvae were reared from 1 to 10 days post-hatch (dph) on a diet of rotifers, wild-caught plankton and newly hatched Artemia sp. nauplii. Results were compared with available data on the relationship between functional morphology and prey selection of Amphiprion frenatus to establish patterns of functional morphology and prey selection between the larvae of two species of coral-reef fishes. Larvae of both species exhibited an increase in selection of larger prey through ontogeny coincident with an increase in the complexity of the feeding apparatus. The first elements to ossify in larvae of both species were the pharyngeal teeth ( A. clarkii : 5 dph, near ± s.d. Standard length, L _S,4· 3 ± 0· 2 mm; A. frenatus : 5 dph, L _S5· 0 ± 0· 4 mm) which, in combination with the development of a more functional feeding apparatus, may have permitted larvae to better process new types and sizes of prey. Prey items, however, were selected differentially between the two fish species, which could not be fully explained by the functional state of the feeding apparatus. While prey selection is influenced by the functional state of the feeding apparatus, all aspects of larval fish biology (morphology, behaviour and physiology) should be considered.     

3D morphology of pharyngeal dentition of the genus Capoeta (Cyprinidae): Implications for taxonomy and phylogeny

Capoeta is a herbivorous cyprinid fish genus, widely distributed in water bodies of Western Asia. Recent species show a distinct biogeographic pattern with endemic distribution in large fluvial drainage basins. As other cyprinids, the species of this genus are characterized by the presence of the pharyngeal bone with pharyngeal teeth. Despite this, the detailed morphology of the pharyngeal teeth, its interspecific and topologic variations, and the importance for taxonomy and phylogeny of the genus Capoeta are still not established. For the first time, a detailed comprehensive study of the pharyngeal dentition of 10 Capoeta species has been provided. The morphologic study of the pharyngeal dentition bases on the 3D microtomography and follows the purpose to evaluate the potential taxonomic and phylogenetic signals of these elements, as well as to study interspecific and topologic variations of the pharyngeal teeth. In this study, we propose a new methodology to categorize the studied pharyngeal teeth in 18 shape classes. The results of this study show that the detailed 3D morphology of the pharyngeal teeth is a useful tool for the identification of isolated teeth at the generic and/or specific level and that in certain cases, the tooth position in the teeth rows can be identified. Additionally, the preliminary analysis shows that the morphology of the pharyngeal teeth provides a potential phylogenetic signal. Both these patterns are very important for the taxonomy of cyprinid fishes and especially can be applied to fossil records.     

鲤咽齿个体发生及其与近缘种间关系的比较研究

鲤具鲤科咽齿个体发生的共同性征,又呈现其种的独特性状.主要特性;(1)主列齿相连3齿胚几乎同时出现、同时脱落,形成3个相连齿种同时置换的特殊模式;(2)主列齿发生中曾出现4枚齿,替换3代后A_4齿退化消失,最终齿式1.1.3-3.1.1,成为迄今3列咽齿的鱼类中齿数最少的种类.鲤与其近缘种间系统关系比较结果;依最近缘属顺次排列为中鲤、原鲤、肥鲤;而最近缘的亚科为肥亚科.       

Influence of development pace on pharyngeal teeth formula in Abramis brama (L.) bream: experimental data

An experiment on acceleration and retardation of ontogenesis with thyroid manipulation has revealed direct changes in definitive dentition of pharyngeal bones in Abramis brama bream. As development pace accelerates, the number of teeth reduces to the formula 5-4. When development pace slows down, this number increases to the formula 6-5. Moreover, an additional minor row of teeth (1.6-5.1, 2.6-5.2) is formed. The observed changes transcend typical changes happening in nature. It is assumed that heterochronies provoke changes in the number of teeth.     

Muscle fiber types and functional demands in feeding mechanisms of fishes

Profiles of muscle fiber types and pharyngeal jaw dentition vary in accordance with trophic demands and skeletal organization in teleost fishes. Carnivorous, omnivorous, and molluscivorous members of the ecologically analogous Cichlidae and Centrarchidae were compared in terms of their pharyngeal jaw anatomy and branchial muscle histochemistry. The two families differed greatly in patterns of tooth form, wear, and replacement. Four muscle fiber type patterns were discoverd: (1) single fiber, (2) zoned, (3) mosaic, and (4) zoned-mosaic. Multiple fiber type muscles were more prevalent in fishes that masticate tough foods with their pharyngeal jaws. Such muscles were also more prevalent in cichlids than in centrarchids. It appears that muscles with multiple fiber types in lower vertebrates are, as a rule, compartmentalized, whereas in higher vertebrates, multiple fiber type muscles are a musaic matrix. The occurrence of mosaic patterns in some fish branchial muscles, however, suggests that mosaic muscles are initially single fiber type muscles exposed to complex functional demands, such as food preparation. Furthermore, it is plausible that the evolutionary replacement of the lower vertebrate zoning pattern by the higher vertebrate mosaic matrix is directly related to the effects of gravity, a force more influential on terrestrial than on aquatic organisms.     

On the systematic position of the genus Petroschmidtia Taranetz et Andriashev, 1934 (Perciformes: Zoarcidae)

Following a comparative analysis of the morphological characters of the representatives of the genera Petroschmidtia and Lycodes, some previously proposed diagnostic characters of Petroschmidtia are confirmed and ascertained and several additional characters are suggested. The conclusion on the taxonomic validity of the genus Petroschmidtia is confirmed. Petroschmidtia differs from Lycodes in the following features: teeth and tooth plates on the vomer and palatinum are lacking; bone fontanels of the supraorbital canal on the frontale are lacking; the vomer is shortened; the ethmoidalia lateralia are narrowed, bearing a pocketlike cavity inside the lateral lobes; the fan-like expanded outgrowth of the supraoccipitale is short, blunt; the dentale is shortened; the radialia are dorsoventrally flattened, the lowest of which is the largest. The genus Petroschmidtia is assumed to be morphologically more closely related to Lycodes than any other of the Lycodinae.     

Conserved deployment of genes during odontogenesis across osteichthyans

Odontogenesis has only been closely scrutinized at the molecular level in the mouse, an animal with an extremely restricted dentition of only two types and one set. However, within osteichthyans many species display complex and extensive dentitions, which questions the extent to which information from the mouse is applicable to all osteichthyans. We present novel comparative molecular and morphological data in the rainbow trout (Oncorhynchus mykiss) that show that three genes, essential for murine odontogenesis, follow identical spatial-temporal expression. Thus, at all tooth bud sites, epithelial genes Pitx-2 and Shh initiate the odontogenic cascade, resulting in dental mesenchymal Bmp-4 expression, importantly, including the previously unknown formation of replacement teeth. Significantly, this spatial-temporal sequence is the same for marginal and lingual dentitions, but we find notable differences regarding the deployment of Pitx-2 in the developing pharyngeal dentition. This difference may be highly significant in relation to the theory that dentitions may have evolved from pharyngeal tooth sets in jawless fishes. We have provided the first data on operational genes in tooth development to show that the same signalling genes choreograph this evolutionary stable event in fishes since the osteichthyan divergence 420 Myr ago, with the identical spatial-temporal expression as in mammals.     

Variability in the number of tooth rows in the pharyngeal dentition of Barbus intermedius (Teleostei; Cyprinidae): genetic,hormonal and environmental factors

The variability of pharyngeal dentition in a natural population of B. intermedius and effects of genetic, hormonal and environmental factors on the number of tooth rows in the pharyngeal dentition in offspring from wild‐caught parents have been investigated. It was revealed that: (i) about 10% of fish from natural population have four‐rowed dentition instead of three‐rowed dentition characteristic for this species; (ii) the presence of the additional tooth row is not an abnormality of tooth replacement since it occurs symmetrically on both sides; (iii) occurrence of the fourth row of teeth is heritable since laboratory‐reared offspring from parents with four‐rowed dentition have the same dentition. Even if one of the parents had four‐rowed dentition the percentage of four‐rowed individuals in the progeny was significantly higher than in progeny from parents with normal (three rowed) dentition; (iv) the number of tooth rows appears to be hormonally controlled: high levels of thyroid hormone result in a decrease in the number of tooth rows to two. In contrast, deficiency of this hormone results in an increase to four rows; (v) no differences in the number of tooth rows were found in fish reared under 17°C, 24°C, 30°C and room temperature (20–26°C).     

鲤形目鱼类咽齿形态及发育的比较研究

对鲤形目所属６科类的咽龄形态及个体发育模型进行了较详细的比较研究。结果得出除双孔鱼科鱼类未形成咽齿外,其它５科鱼类在咽齿发生的过程中具有齿着生方向完全相反的两种发育模式。以亚口鱼科,鳅科和平鳍鳅为一类的齿后向增长的类型和以鲤科另一类的齿同增长的类型。     

A novel pharyngeal expansion mechanism in the yellow-spotted fanray, Platyrhina tangi (Elasmobranchii: Batoidea), with special reference to the function of the fifth ceratobranchial cartilage in batoids

Expansion of the ‘pharynx’ during breathing or capturing prey in fishes generally involves posteroventral retraction of the hyoid arch. However, the hyoid arch structure of batoid fishes (skates, rays, guitarfishes, and sawfishes) is unique, and how they expand the pharyngeal cavity is poorly understood. To investigate the mechanism of pharyngeal expansion during breathing in the yellow-spotted fanray, Platyrhina tangi, we conducted anatomical and kinematic investigations of the pharyngeal region. Our study revealed that the yellow-spotted fanray and sharks have different skeletal linkage systems for pharyngeal expansion. During pharyngeal expansion in the yellow-spotted fanray, the hyoid bar and branchial apparatus rotate ventrally around the hinge joint between the fifth ceratobranchial cartilage and the pectoral girdle. This pharyngeal expansion mechanism appears to be widespread among batoid fishes and is unique among cartilaginous fishes (sharks, batoids, and holocephalans). Batoid fishes possibly developed this pharyngeal expansion mechanism during early batoid evolution.