Ocular lesions associated with attachment of the copepod Ommatokoita elongata (Lernaeopodidae: Siphonostomatoida) to corneas of Pacific sleeper sharks Somniosus pacificus captured off Alaska in Prince William Sound

Twenty eyes from 10 Pacific sleeper sharks Somniosus pacificus, infected with the copepod Ommatokoita elongata, were collected in Prince William Sound, Alaska, and the eyes of an additional 18 S. pacificus captured in the same area were inspected for copepods. Prevalence of infection by adult female O. elongata was 97% (n = 28); mean intensity of infection was 1.89 (+/-1SD = 0.32) adult female copepods per infected shark and 1.0 (+/- 1SD = 0.0) adult female copepods per infected eye. Five of the 20 collected eyes were infected by O. elongata chalimi, and 9 of 20 eyes had 1 to several remnants of bullae embedded in the cornea. Bullae were each associated with a corneal opacity, and anchoring plugs of chalimi were associated with pinpoint lesions in the cornea or conjunctiva. All eyes exhibited marked edema and erosion of the bulbar conjunctiva, and this torus-shaped lesion corresponded to each O. elongata adult female's presumed feeding and abrasion radius. Histological examinations revealed lesions in the anterior segment of eyes to be generally similar, but graded, in severity, and in all eyes they involved the conjunctiva, cornea, filtration angle, and iris. Epithelial lesions were characterized by corneal ulceration, dysplasia, hyperplasia, and heterophilic keratitis, and by ulcerative conjunctivitis accompanied by epithelial hyperplasia with rete peg formation. Disorganization of fibers, necrosis, mineralization, minimal heterophilic influx, and perilimbic neovascularization were associated with bullae in the corneal stroma. Within the limbus there was diffuse histiocytic and lymphocytic inflammation and marked lymphofollicular hyperplasia. Heterophilic and mononuclear anterior uveitis affecting the filtration angle and anterior surface of the iris was also observed in most eyes. One eye had a partial transcorneal prolapse of a ruptured lens, with degenerative changes in the ruptured lens and severe keratitis associated with the anchoring devices of an adult copepod and several chalimi. Fourteen eyes exhibited 1 to several, randomly distributed, small, round to irregular, corneal opacities or pits that were not associated with copepods, and it is likely that these opacities represented lesions associated with adult female or larval anchoring devices from past infections. The avascular cornea represents a niche that is somewhat shielded from host immune reactions, and this, and the fact that the general body surface of sleeper sharks is covered by tall and sharp placoid scales, may partially explain the corneal attachment of O. elongata adult females. It was concluded that O. elongata infections can lead to severe vision impairment in Pacific sleeper sharks but that these infections do not significantly debilitate hosts because they probably do not need to rely on acute vision for their survival.     

Proteocephalidean larvae (Cestoda) in naturally infected cyclopid copepods of the upper Paran River floodplain,Brazil

The occurrence, prevalence and infection intensity of proteocephalidean larvae in naturally infected intermediate hosts of the Upper Paran River floodplain are reported. A total of 5,206 zooplanktonic and benthic organisms were analyzed, namely cyclopid (2,621) and calanoid (1,479) copepods, cladocerans (704), rotifers (307), chironomid larvae (41) and ostracods (54). Eight cyclopid copepods - two copepodids, one male and five females - comprising 0.3% of the cyclopid copepods examined, were naturally infected. The male infected belonged to a species of Paracyclops, and the females to Paracyclops sp., Thermocyclops minutus and Mesocyclops longisetus.     

A Computational Study of the Hydrodynamics in the Nasal Region of a Hammerhead Shark (Sphyrna tudes): Implications for Olfaction

The hammerhead shark possesses a unique head morphology that is thought to facilitate enhanced olfactory performance. The olfactory chambers, located at the distal ends of the cephalofoil, contain numerous lamellae that increase the surface area for olfaction. Functionally, for the shark to detect chemical stimuli, water-borne odors must reach the olfactory sensory epithelium that lines these lamellae. Thus, odorant transport from the aquatic environment to the sensory epithelium is the first critical step in olfaction. Here we investigate the hydrodynamics of olfaction in Sphyrna tudes based on an anatomically-accurate reconstruction of the head and olfactory chamber from high-resolution micro-CT and MRI scans of a cadaver specimen. Computational fluid dynamics simulations of water flow in the reconstructed model reveal the external and internal hydrodynamics of olfaction during swimming. Computed external flow patterns elucidate the occurrence of flow phenomena that result in high and low pressures at the incurrent and excurrent nostrils, respectively, which induces flow through the olfactory chamber. The major (prenarial) nasal groove along the cephalofoil is shown to facilitate sampling of a large spatial extent (i.e., an extended hydrodynamic “reach”) by directing oncoming flow towards the incurrent nostril. Further, both the major and minor nasal grooves redirect some flow away from the incurrent nostril, thereby limiting the amount of fluid that enters the olfactory chamber. Internal hydrodynamic flow patterns are also revealed, where we show that flow rates within the sensory channels between olfactory lamellae are passively regulated by the apical gap, which functions as a partial bypass for flow in the olfactory chamber. Consequently, the hammerhead shark appears to utilize external (major and minor nasal grooves) and internal (apical gap) flow regulation mechanisms to limit water flow between the olfactory lamellae, thus protecting these delicate structures from otherwise high flow rates incurred by sampling a larger area.     

鲻鱼嗅囊组织形态结构观察及功能探讨

实验用鱼为全长35.5~40.0 cm的野生鲻(Mugil cephalus),采用石蜡切片以及透射电镜技术对鲻的嗅囊以及嗅板细胞进行观察。结果表明:鲻的嗅觉器官由左右两个呈扁平椭球形嗅囊构成,分别由前后两个鼻孔与外界相通。嗅囊长径与眼径之比为0.80,长径与短径之比为2.09。嗅囊的嗅轴左右两边分别有垂直于嗅轴并向上倾斜排列整齐的18~25个披针形嗅板,只有初级嗅板未见次级嗅板。嗅板由中央髓和两侧的嗅上皮两部分构成,中央髓由疏松的结缔组织和毛细血管组成。嗅上皮又分为感觉区和非感觉区,感觉区位于嗅板的内侧,具有发达纤毛,呈连续分布状态,非感觉区位于嗅板边缘,细胞纤毛较少。通过光镜和电镜的综合研究结果显示嗅上皮细胞大致可分为5类:基细胞、支持细胞、纤毛非感觉细胞、纤毛感觉细胞和柱状细胞。文章讨论了鲻的感官活动类型。     

Factors affecting abundance of Triaenophorus infection in Cyclops strenuus, and parasite-induced changes in host fitness

Factors affecting the abundance of Triaenophorus crassus and Triaenophorus nodulosus procercoids in their copepod first intermediate host, Cyclops strenuus, and effects of infection on feeding behaviour, reproduction and survival of the host were studied experimentally. When exposed to the same number of coracidia, copepods harboured considerably less procercoids in the trials where ciliates or Artemia salina nauplii were given as alternative food items. The prevalence of infection was higher in adult copepods as compared with copepodite stage IV and stage V, and higher in stage V than in stage IV. The prevalences in adult females and males did not differ significantly from each other. The frequency of females carrying egg sacs was lower among infected than among exposed uninfected and unexposed copepods. The rate of feeding on Artemia nauplii remained at the same level in uninfected copepods, but decreased strongly in infected copepods during 7 days p.i. The survival of unexposed, exposed uninfected and infected copepods did not differ significantly from each other for the first 11 days post-exposure, but the mortality of infected copepods increased significantly after 3 weeks post-exposure. However, the rate of development and mortality of copepods might have been affected by the apparently arrested development of stage IV copepodites found in the experiment. Some of the contradictions between these results and earlier observations are suggested to be caused by the differences in the duration of exposure, intensity of infection and duration of observation post-exposure in the present study as compared with other experiments.     

Functional morphology of the gills of the shortfin mako,Isurus oxyrinchus,a lamnid shark

This study examines the functional gill morphology of the shortfin mako, Isurus oxyrinchus, to determine the extent to which its gill structure is convergent with that of tunas for specializations required to increase gas exchange and withstand the forceful branchial flow induced by ram ventilation. Mako gill structure is also compared to that of the blue shark, Prionace glauca, an epipelagic species with lower metabolic requirements and a reduced dependence on fast, continuous swimming to ventilate the gills. The gill surface area of the mako is about one‐half that of a comparably sized tuna, but more than twice that of the blue shark and other nonlamnid shark species. Mako gills are also distinguished from those of other sharks by shorter diffusion distances and a more fully developed diagonal blood‐flow pattern through the gill lamellae, which is similar to that found in tunas. Although the mako lacks the filament and lamellar fusions of tunas and other ram‐ventilating teleosts, its gill filaments are stiffened by the elasmobranch interbranchial septum, and the lamellae appear to be stabilized by one to two vascular sacs that protrude from the lamellar surface and abut sacs of adjacent lamellae. Vasoactive agents and changes in vascular pressure potentially influence sac size, consequently effecting lamellar rigidity and both the volume and speed of water through the interlamellar channels. However, vascular sacs also occur in the blue shark, and no other structural elements of the mako gill appear specialized for ram ventilation. Rather, the basic elasmobranch gill design and pattern of branchial circulation are both conserved. Despite specializations that increase mako gill area and efficacy relative to other sharks, the basic features of the elasmobranch gill design appear to have limited selection for a larger gill surface area, and this may ultimately constrain mako aerobic performance in comparison to tunas. J. Morphol. 271:937–948, 2010. © 2010 Wiley‐Liss, Inc.     

Costs and benefits of maternal behaviour in the green lynx spider (Oxyopidae,Peucetia viridans)

I examined the adaptiveness of maternal behaviour in the green lynx spider Peucetia viridans (Hentz), by measuring the costs and benefits to the female of egg-sac tending. P. viridans guards her egg sac for 6–8 weeks until the young have emerged and dispersed. I removed females from egg sacs in the field either immediately after oviposition or after they had guarded the egg sacs for 2 weeks, and compared the fate of these sacs with that of control sacs which had females present throughout. Survival rates of egg sacs were significantly improved by the presence of a female. The major sources of mortality were ant predation and sac dislodgement, both of which were significantly reduced by a guarding female, and mantispid brood parasitism, which was not affected by the female. To measure the spiders' lifetime reproductive output, I allowed caged females to construct egg sacs. Half had their first egg sac removed shortly after oviposition, while half were allowed to guard. Significantly more non-guarding than guarding females produced second egg sacs. Thus for the green lynx spider, egg sac guarding decreases lifetime egg production, but increases offspring survival. Under north Florida conditions, the benefits of guarding outweight the costs, and the females have a higher lifetime reproductive success than if they did not guard.     

A new genus and species of hyponeoid (Copepoda) from the olfactory sac of a gulper shark Centrophorus sp. (Squaliformes: Centrophoridae) captured off Madagascar

Greeniedeets buccaneer n. gen., n. sp. (Hyponeoidae, Siphonostomatoida, Copepoda) infects the olfactory sac of a gulper shark, Centrophorus sp. (Centrophoridae, Squaliformes) off Madagascar. The adult female of Greeniedeets buccaneer n. gen., n. sp. is most easily distinguished from other hyponeoids (Hyponeoidae) by its possession of a genital complex that is horseshoe shaped in dorsal view. An amended family diagnosis for Hyponeoidae and diagnostic key to hyponeoids based on adult females are provided.     

Morphology and anatomy of the olfactory organs of the marine fish Thynnus thunnina (Cuv. et Val.)

The authors studied the morphology and anatomy of the olfactory organs of the marine fish Thynnus thunnina. The fish has a single nasal orifice. The round olfactory rosette has a central axis surrounded by radially oriented lamellae. The olfactory rosette (olfactory organ) is provided with two accessory nasal sacs - a lacrimal and an ethmoidal sac. Thynnus thunnina was classified in Teichmann's (1954) group II, i.e., the "eye-fishes", whose vision is better developed than their olfaction.     

Impact of a castrating trematode, Neophasis sp., on the common whelk, Buccinum undatum, in the northern Gulf of St. Lawrence

We observed heavy trematode infections of whelks, Buccinum undatum, from the Mingan Islands, eastern Canada, by larval stages of a species of Neophasis. Only sexually mature whelks were infected, 23% of mature females and 15% of mature males, and prevalence increased rapidly with whelk size. In most cases the parasite completely occupied the gonad, causing castration. The digestive gland was also infected, although to a lesser degree (0% to 50% occupation), and a marked reduction in the mass of the penis was associated with the infection. A decrease in the proportion of whelks with a highly infected digestive gland between May and August 1994 suggested mortality of infected individuals. Whelks held for 12 to 15 months in the laboratory retained the infection but did not show significant mortalities (possibly because food was abundant and predators absent). The larval stage of Neophasis sp. found in whelks was a cercaria; however, the tail easily detached. The putative infective stage (metacercaria) was not observed but may be present in whelks in late winter and early spring. Other trematode parasites observed were adult Steringophorus furciger in the stomach and larval Renicola sp. in the digestive gland.     

Biology of a hoplonemertean from the branchial chambers of the pinnotherid crab Zaops (= Pinnotheres) ostreum

The pea crab, Zaops ostreum, a symbiont in the mantle cavity of the American oyster (Crassostreavirginica), is itself a host to a symbiotic nemertean. Thisnemertean belongs to the genus Carcinonemertes, and issimilar to or possibly the same as C. pinnotheridophila,known from another sympatric pinnotherid crab, Pinnixachaetopterana. Living in mucous sheaths within the gillchambers of female crabs, the life cycle of the nemertean isintimately synchronized with and dependent on the crab's reproduction. A total of 138 pea crabs were collected andexamined for nemerteans during the summers of 1965 to 1967 atBeaufort, North Carolina, U.S.A.; of these 97 (70%) were mature(5th stage) female crabs. Mature females harbored thenemerteans, and had a prevalence of 39.2%. A maximum of 20worms was found in the gill chambers of a single crab, 9 ofwhich were the red, eyeless, mature female worms, along with 11colorless males. Worm egg sacs were attached to the pleopods ofovigorous crabs; a maximum of 293 sacs was recorded in anindividual crab with 7 mature females. At about 110 eggs persac, this translates to a potential production of >32 200nemertean larvae. Since female Z. ostreum may live for 2to 3 yr and produce two broods of eggs per year (beyond thefirst year), the reproductive potential of the symbionts may beeven greater. Gills of crabs with more than one mature femalewere usually covered by the worm sheaths, and were frequentlydamaged (gnarled, torn, silted, etc.). The sternum of infestedcrabs was often damaged due to the projection of worm sheathsthrough it to the subabdominal region. There the egg sacs weredeposited on the pleopods to develop along with the crabembryos.     

The vocal sac as a visual cue in anuran communication: an experimental analysis using video playback

Acoustic signals produced by most anurans are accompanied by inflation of a conspicuous vocal sac. We presented female túngara frogs, Physalaemus pustulosus, with acoustic playback of the male advertisement call, synchronized with a video playback of vocal sac inflation. Females significantly preferred a stimulus combination including vocal sac inflation over an identical set of stimuli with the vocal sac inflation removed. Neither a moving rectangle bearing the gross contrast and spatiotemporal properties of the vocal sac inflation sequence, nor the image of a noncalling male significantly enhanced the attractiveness of the acoustic stimulus. Both the form and spatiotemporal properties of the vocal sac thus appear to be salient to females. The results indicate that the vocal sac can serve as a visual cue, which may account for the conspicuous pigmentation found on the vocal sacs of males in many species. Gular inflation in synchrony with a call may function to facilitate female localization of individual males in an aggregation.     

Impact of a novel species of Nosema on the southwestern corn borer (Lepidoptera: Crambidae)

A study was undertaken to elucidate the impact of an undescribed Nosema sp. on the southwestern corn borer (SWCB; Diatraea grandiosella Dyar). The Nosema sp. (isolate 506) included in the study was isolated from an overwintering SWCB larva in Mississippi. It was highly infectious per os, with a median infective dose of 2.0 x 10(3) spores per larva. Even at the highest dosage tested (10(7) spores per larva), minimal mortality (< or = 3%) was observed in infected larvae, pupae, and adults reared in the laboratory on an artificial diet. However, infected pupae (0- and 7-d-old) were smaller, and the time to adult eclosion from pupation was slightly increased. Furthermore, the number of eggs produced by infected SWCB female moths substantially decreased (32%), and this effect was most pronounced on day 2, when the greatest number of eggs were oviposited by infected and noninfected moths. For eggs produced by infected females mated with infected males, hatch was slightly decreased by 16 and 15% for eggs laid on days 2 and 3, respectively. In addition, egg hatch was reduced in eggs oviposited by noninfected females mated with infected males on day 3. A low prevalence of infection (< 6%) was observed in the F1 generation originating from infected females mating with noninfected males, from noninfected females mating with infected males, and from infected females mating with infected males. Nosema 506 spores were observed in the proximity of reproductive tissues of infected female and male moths. Spores also were detected on the chorion surface and within eggs laid by infected females. Furthermore, 1-11% of larvae hatching from surface-sterilized eggs were infected by Nosema 506 indicating a transovarial mechanism of transmission.     

Parasitized female mice display reduced aversive responses to the odours of infected males.

The present study showed that parasites influence both the responses of uninfected females to males and the responses of female hosts to infected males. In female laboratory mice one of the consequences of exposure to the olfactory cues associated with an infected male was a reduction of the reactivity to a thermal surface, i.e. pain inhibition or analgaesia. Uninfected oestrous and non-oestrous female mice displayed marked analgaesic responses after exposure to the odours of males infected with either the enteric single-host nematode parasite, Heligmosomoides polygyrus, or the protozoan parasite, Eimeria vermiformis. The uninfected oestrous females distinguished between infected and physically stressed males, displaying a greater analgaesic response to the odours of infected males. These analgaesic responses and their anxiety/ fearfulness-associated behavioural correlates could elicit either a reduced interest in, or avoidance of, parasitized males by females. Oestrous female mice infected with H. polygyrus displayed a reduced analgaesic response to the odours of the infected males and differentially responded to the odours of males infected with either the same (H. polygyrus) or a different parasite (E. vermiformis). An exposure time of 1 min elicited minimal responses to the odours of males infected with the same parasite, H. polygyrus, and an attenuated, though significant, non-opioid peptide-mediated analgaesic response to males infected with E. vermiformis. An exposure time of 30 min elicited similar markedly reduced endogenous opioid peptide-mediated analgaesic responses to the odours of both of the categories of infected males. The responses to the odours of a stressed male were, however, unaffected by the parasitic infection. The reduced analgaesic responses of the parasitized females to the odours of infected males may involve either enhanced odour familiarity and responses to group odour templates and/or neuromodulatory shifts resulting in reduced fearfulness and potentially greater interest in the infected males.     

Apertures of Craniate offactory Organs

The olfactory organs of craniates appear to derive from an anterior pair of erstwhile branchiothyria and their adjacent epidermal, neurogenic placodes. The organ is termed saccus nasalis if its source is the ectobranchial invagination of the branchiothyrium, and the saccus rhinalis if its source is the entobranchial evagination of the branchiothyrium. Nasal sacs occur in gnathostomes and lampreys, and rhinal sacs in hagfish. It is difficult, therefore, to avoid the conclusion that the olfactory organ has evolved more than once. The rhinal sac has only one aperture, the postica, which represents an internal branchiothyric orifice. Partial fusion of the right and the left rhinal sac led to the development of a postica communis. The nasal sac has either one, two or three apertures. Altogether there are nine different aperturae sacci nasalis, viz. the naris, the foris, the tremiscus, the two nariculae, the rimilla, the portula, the opiscus and the janua. The janua represents an external branchiothyric orifice and occurs in lampreys. The naris and the foris arose by subdivision of the orifice from which the janua emanated; they are found in osteolepipods. The naris is also found in urodeles, porolepiforms and some teleosts. The incurrent and excurrent naricules resulted from bipartition of a naris and are present in actinopterygians, coelacanthiforms, brachiopterygians, dipnoans and elasmobranchiomorphs. Of the four remaining openings of the nasal sacs the rimilla results from an inpushing of the epidermis, the portula from an outpocketing of the nasal sac, and the tremiscus from a combination of two such movements, the one inward and the other outward. Rimillae occur in cyprinodonts, anurans, urodeles, caecilians and porolepiforms, portulae in uranoscopids and bathydraconids, and tremisci in urodeles and porolepiforms. The opiscus, finally, is the opening through which the vomeronasal organ communicates with the oral cavity. It occurs in most lizards and snakes and probably also in some mammals.     

Temporal and Spatial Distribution of Male Scent Marks in the Polygynous Greater Sac-Winged Bat

Scent marks are relatively long-lived signals that can be perceived by conspecifics when the producer is absent. Therefore, it is often not obvious to whom the signal is directed. In daytime roosts of the polygynous greater sac-winged bat, males scent mark territories with facial gland secretions. Territories are a valuable resource for males, as they offer exclusive courtship opportunities, which results in increased male reproductive success and, consequently, increased male–male competition over territories. The information encoded in male scent marks could, therefore, be either directed at females as part of an olfactory courtship display or at male competitors as part of territorial behaviour. We expected territorial males to scent mark in the morning, shortly before females return to the territory and close to female roosting sites, if scent marks are directed at females as part of the courtship display. And we expected harem males to scent mark at the territory boundaries, where male–male encounters are most likely to occur, if scent marks are directed at male competitors. We found that males marked more frequently in the afternoon, at a time when all females have already left the territory, and harem males marked at the territory boundaries and not inside their territory in the area where females roost. At boundaries males fan volatiles from specialised wing sacs towards competitors outside the territory. Scent marking of male Saccopteryx bilineata might therefore be congruent with the assessment-hypothesis, which states that scent marks offer intruders the possibility to make an olfactory assessment of the territory owner without direct physical interaction. Thus, scent marks of male S. bilineata are most likely influenced by male–male competition and not by female choice.     

The vocal sac of Hylodidae (Amphibia,Anura): Phylogenetic and functional implications of a unique morphology

Anuran vocal sacs are elastic chambers that recycle exhaled air during vocalizations and are present in males of most species of frogs. Most knowledge of the diversity of vocal sacs relates to external morphology; detailed information on internal anatomy is available for few groups of frogs. Frogs of the family Hylodidae, which is endemic to the Atlantic Forest of Brazil and adjacent Argentina and Paraguay, have three patterns of vocal sac morphology—that is, single, subgular; paired, lateral; and absent. The submandibular musculature and structure of the vocal sac mucosa (the internal wall of the vocal sac) of exemplar species of this family and relatives were studied. In contrast to previous accounts, we found that all species of Crossodactylus and Hylodes possess paired, lateral vocal sacs, with the internal mucosa of each sac being separate from the contralateral one. Unlike all other frogs for which data are available, the mucosa of the vocal sacs in these genera is not supported externally by the mm. intermandibularis and interhyoideus . Rather, the vocal sac mucosa projects through the musculature and is free in the submandibular lymphatic sac. The presence of paired, lateral vocal sacs, the internal separation of the sac mucosae, and their projection through the m. interhyoideus are synapomorphies of the family. Furthermore, the specific configuration of the m. interhyoideus allows asymmetric inflation of paired vocal sacs, a feature only reported in species of these diurnal, stream‐dwelling frogs.     

Parthenogenesis in an elasmobranch in the presence of conspecific males

Parthenogenesis has been observed in several elasmobranch species, primarily in public aquaria. The majority of cases of parthenogenesis have occurred either when females were held without males or once a male was removed from a female's habitat. Here we report a second instance of parthenogenesis in a zebra shark female that was housed with conspecific mature males. This study calls into question the conditions under which elasmobranch females undergo parthenogenesis.