Tip Of Rostrum Research Articles

Two new species of Cerviniella Smirnov, 1946 (Copepoda, Harpacticoida, Aegisthidae) from the Yellow Sea, Korea.

Two new species, Cerviniellabisegmentasp. nov. and C.permixtasp. nov., are described in detail with illustrations based on females from the Korean Yellow Sea. These species lacking the fourth leg endopod belong to the mirabilipes group, one of two species groups within the genus Cerviniella Smirnov, 1946. Both species can be distinguished from each other by the surface ornamentation of the cephalothorax, shape of the rostrum tip, antennule segments, armature formula of thoracic legs 1-4, and length ratio of the caudal rami. Cerviniellabisegmentasp. nov. is characterized by a short caudal ramus and a two-segmented antennary exopod, which are unique within the genus. Cerviniellapermixtasp. nov. differs from other congeners of the mirabilipes group by the seven-segmented antennule, the armature formulae of the exopod of the antenna and thoracic legs 1-4, and the modified apical inner element of the second endopodal segment of the second leg. The present study is the first to identify the genus Cerviniella in Korean waters, resulting in extension of its distribution area to East Asia.

Taxonomic contribution to the knowledge of the subgenus Scheloribates (Topobates) (Acari, Oribatida, Scheloribatidae), with description of a new species from China

Species from China of the subgenus Scheloribates (Topobates) are studied, with description of a new species Scheloribates (Topobates) tibetensis sp. nov. based on adult specimens from Tibet. The new species differs from S. (T.) lanceolatus Wallwork, 1977 by heterotridactylous (versus monodactylous), shorter interlamellar seta, not forward to the tip of rostrum (versus longer interlamellar seta, beyond forward to the tip of the rostrum), genital seta g1 longer than g2–g4 (versus genital seta g1 similar to g2–g4 in length). A key to known species of Scheloribates (Topobates) is provided.

Lacunae rostralis: A new structure on the rostrum of sailfish Istiophorus platypterus.

Recent comparative studies of billfishes (Istiophoridae and Xiphiidae) have provided evidence of differences in the form and function of the rostra (bill) among species. Here, we report the discovery of a new structure, lacuna rostralis, on the rostra of sailfish Istiophorus platypterus, which is absent on the rostra of swordfish Xiphias gladius, striped marlin Kajikia audax and blue marlin Makaira nigricans. The lacunae rostralis are small cavities that contain teeth. They were found on the ventral rostrum surface of all I. platypterus specimens examined and dorsally in half of them. Ventrally, the lacunae rostralis were most prominent in the mid-section of the rostrum. Dorsally, they occurred closer to the tip. The density of lacunae rostralis increased towards the rostrum tip but, because they are smaller in size, the percentage of rostrum coverage decreased. The teeth located within the lacunae rostralis were found to be different in size, location and orientation from the previously identified micro-teeth of billfish. We propose two potential functions of the lacunae rostralis that both relate to the use of the bill in feeding: mechanoreception of prey before tapping it with the bill and more efficient prey handling via the creation of suction, or physical grip.

Evidence for tactile foraging in pterosaurs: a sensitive tip to the beak of Lonchodraco giganteus (Pterosauria, Lonchodectidae) from the Upper Cretaceous of southern England

The sense of touch is important for hunting and feeding in vertebrates, especially when visual cues are unreliable. Foramina in the jaws and face, associated with nerves and sensory organs, may provide information about feeding. Pterosaurs, many of which had large, well-developed eyes, are often assumed to have been visual feeders. Here, we show that the lonchodectid pterosaur Lonchodraco giganteus (Bowerbank, 1846) has clusters of circular foramina at the anterior mandibular symphysis (the odontoid) and on the lateral margins of the rostrum that indicate enhanced sensitivity of the rostrum tip. This pattern implies tactile foraging. The foramina were likely occupied by Herbst corpuscles or similar integumentary sensory micro-organs (ISO). They presumably served a sensory function at the jaw tip to enhance food gathering. A similar morphology occurs in some avians that feed using tactile cues, including probe feeders such as kiwis, sandpipers, and ibises, tactile hunters such as spoonbills, and filter feeders such as ducks and flamingos. The beak morphology of L. giganteus does not closely resemble that of these birds, and thus its modus operandi for feeding remains speculative, however tactile foraging for fish or invertebrates in shallow water seems likely. Like birds, pterosaurs evolved a diverse range of feeding strategies.

Click reception in the harbor porpoise (Phocoena phocoena): Effects of electrode and contact transducer location on the auditory brainstem response.

Unlike terrestrial mammals that have unambiguous aerial sound transmission pathways via the outer ear and tympanum, sound reception pathways in most odontocetes are not well understood. Recent studies have used auditory brainstem response (ABR) measurements to examine sound reception pathways. This study sought to determine how sound source placements, recording electrode arrangements, and ABR peak analyses affect interpretations of sound reception in the harbor porpoise (Phocoena phocoena). Click stimuli were delivered in air from a contact transducer ("jawphone"). Early ABR peaks (representing auditory nerve responses), and later peaks reflecting higher brainstem activity, were analyzed across jawphone and recording electrode positions. Auditory nerve responses were similar for jawphone placements from the ipsilateral posterior mandible to the tip of the rostrum. Later peaks, however, suggested a possible region of highest sensitivity midway between the posterior mandible and the rostrum tip. These findings are generally similar to previous data for porpoises. In contrast to auditory nerve responses that were largest when recorded near the ipsilateral meatus, later ABR peaks were largest when recorded with a contralateral (opposing) electrode. These results provide information on the processes underlying peaks of the ABR, and inform stimulus delivery and ABR recording parameters in odontocete sound reception studies.

Morphometry and microanatomy of the barbels of the common sawshark Pristiophorus cirratus (Pristiophoridae): implications for pristiophorid behaviour.

The internal anatomy of the barbels of the common sawshark Pristiophorus cirratus was examined with light microscopy to clarify their sensory role. No sensory structures such as taste buds (chemoreception), ampullae of Lorenzini (electroreception) or free neuromasts (lateral line mechanoreception) could be located in the barbels. The presence of bundles of nerve fibres, however, indicates a tactile function for the barbels. Conveyance of information regarding potentially damaging stimuli (nociception) and temperature (thermoception) cannot be excluded at this stage. It is hypothesized that the barbels are used by P. cirratus to locate prey in both the water column and on the substratum via wake detection and sensing changes in surface texture. The barbels may also be involved in the detection of water currents for rheotaxis. Regression analyses on P. cirratus morphometric data showed that the width of the rostrum at two sections (the barbels and the rostrum tip) does not significantly correlate with total length. The regression analyses also suggested that the barbels of P. cirratus may be lateralised.

Dead-twig discrimination for oviposition in a cicada, Cryptotympana facialis (Hemiptera: Cicadidae)

In phytophagous insects, in spite of some general advantages of oviposition on a vital part of their host food plants, certain species prefer dead tissues for oviposition. In the present study, we examined oviposition-related behaviors of a cicada, Cryptotympana facialis (Walker), which lays eggs exclusively into dead twigs. From behavioral observation of females experimentally assigned to live or dead plant material, we found that egg laying into freshly cut live twigs is abandoned in two phases, i.e., before and after initiation of egg nest-creating behavior with the ovipositor. Behavioral sequence analyses revealed that oviposition was generally preceded by rubbing with the rostrum tip and brief stylet-penetration behavior, suggesting that oral assessment may play a primary role in decision-making of oviposition in the earlier discriminating phase. From the similarity in behavioral flows of this assessment to vital tissue-seeking behaviors, cicada females are presumed to judge a twig as dead by sensing the absence of vital cues. These findings contribute to understanding a behavioral basis of dead plant recognition for oviposition, potentially giving an insight into ecological and evolutionary aspects of diverse oviposition preferences.

Early development of rostrum saw-teeth in a fossil ray tests classical theories of the evolution of vertebrate dentitions.

In classical theory, teeth of vertebrate dentitions evolved from co-option of external skin denticles into the oral cavity. This hypothesis predicts that ordered tooth arrangement and regulated replacement in the oral dentition were also derived from skin denticles. The fossil batoid ray Schizorhiza stromeri (Chondrichthyes; Cretaceous) provides a test of this theory. Schizorhiza preserves an extended cartilaginous rostrum with closely spaced, alternating saw-teeth, different from sawfish and sawsharks today. Multiple replacement teeth reveal unique new data from micro-CT scanning, showing how the ‘cone-in-cone’ series of ordered saw-teeth sets arrange themselves developmentally, to become enclosed by the roots of pre-existing saw-teeth. At the rostrum tip, newly developing saw-teeth are present, as mineralized crown tips within a vascular, cartilaginous furrow; these reorient via two 90° rotations then relocate laterally between previously formed roots. Saw-tooth replacement slows mid-rostrum where fewer saw-teeth are regenerated. These exceptional developmental data reveal regulated order for serial self-renewal, maintaining the saw edge with ever-increasing saw-tooth size. This mimics tooth replacement in chondrichthyans, but differs in the crown reorientation and their enclosure directly between roots of predecessor saw-teeth. Schizorhiza saw-tooth development is decoupled from the jaw teeth and their replacement, dependent on a dental lamina. This highly specialized rostral saw, derived from diversification of skin denticles, is distinct from the dentition and demonstrates the potential developmental plasticity of skin denticles.

Large‐scale multivariate analysis reveals sexual dimorphism and geographic differences in theGray's beaked whale

AbstractGray's beaked whales (Mesoplodon grayi) are medium‐sized odontocete (toothed) cetaceans that are members of the family Ziphiidae. These animals inhabit deep oceanic waters and are rarely seen at sea. Most information is derived from stranded animals and there has been no systematic study of their morphology. We present a multivariate analysis of the morphology ofGray's beaked whales using 80 cranial measurements from 22 individuals and 13 external measurements from 50 individuals. Sparse principal component and linear discriminant function analyses were used to classify samples into sexes. Males and females have markedly different cranial morphology. In particular, females have longer skulls with longer more slender rostra (beaks) in comparison to males. Two variables, depth of the rostrum at mid‐length and tip of rostrum to the right temporal fossa, can classify sex with 100% accuracy. The external body measurements used in this study are more prone to error as they were recorded by a number of observers on carcasses in differing states of decomposition and this is reflected in the level of variance in most measurements. However, analyses of these measurements showed a significant difference between sexes in the distance between (1) the tip of the rostrum to the genital slit, (2) the tip of the rostrum to the blowhole, as found in the cranial analyses and (3) tail fluke width where males have absolutely wider tail flukes than females. Differences in these same measurements were also found between animals stranded on the east and west coasts suggesting a degree of population separation across New Zealand. Finally, we present two linear models that enable the assignment of sex from either skull or external measurements. These models will be useful for future studies as well as the management of these whales and can be applied to archived data where genetic sex assignment is not possible.

Hearing pathways in the Yangtze finless porpoise,Neophocaena asiaeorientalis asiaeorientalis

How an animal receives sound may influence its use of sound. While 'jaw hearing' is well supported for odontocetes, work examining how sound is received across the head has been limited to a few representative species. The substantial variation in jaw and head morphology among odontocetes suggests variation in sound reception. Here, we address how a divergent subspecies, the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) hears low-, mid- and high-frequency tones, as well as broadband clicks, comparing sounds presented at different locations across the head. Hearing was measured using auditory evoked potentials (AEPs). Click and tone stimuli (8, 54 and 120 kHz) were presented at nine locations on the head and body using a suction-cup transducer. Threshold differences were compared between frequencies and locations, and referenced to the underlying anatomy using computed tomography (CT) imaging of deceased animals of the same subspecies. The best hearing locations with minimum thresholds were found adjacent to a mandibular fat pad and overlaying the auditory bulla. Mean thresholds were not substantially different at locations from the rostrum tip to the ear (11.6 dB). This contrasts with tests with bottlenose dolphins and beluga whales, in which 30-40 dB threshold differences were found across the animals' heads. Response latencies increased with decreasing response amplitudes, which suggests that latency and sensitivity are interrelated when considering sound reception across the odontocete head. The results suggest that there are differences among odontocetes in the anatomy related to receiving sound, and porpoises may have relatively less acoustic 'shadowing'.

Hearing pathways in the finless porpoise, Neophocaena phocaenoides, and implications for noise impacts.

How an animal receives sound will influence how it uses or is impacted by sound. While the “jaw hearing” hypothesis is well supported, work has been limited to a few “representative” species. There are clear variations in the jaw and head morphologies of odontocete species suggesting subtle variation in sound reception. Here we address how a divergent cetacean species, the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), receives sound. Noise impacts on this subspecies are a concern as they inhabit waters with many acoustic sources. Hearing was measured using auditory evoked potentials. Click and amplitude modulated tone stimuli were presented at nine locations on the head and body using a jawphone transducer. Thresholds were compared to anatomical dissections and CT scans of porpoise heads. Minimum thresholds and best hearing locations were at the cheek‐fat‐pad and distal to the porpoise bulla. However, thresholds were not substantially different at locations from the rostrum tip to the ear (11.6 dB). This minimal variation is quite different from the 30–40 dB differences found across the head of bottlenose dolphins and belugas suggesting differences in how divergent odontocetes receive sound. Porpoises may have relatively less “shading” of sounds and are potentially more susceptible to masking effects.

Rhynchophorus ferrugineus and Rhynchophorus palmarum

<i>Rhynchophorus ferrugineus </i>and<i> Rhynchophorus palmarum</i>

Behavior of the Grass Shrimp Palaemonetes pugio and its Response to the Presence of the Predatory Fish Fundulus heteroclitus

The grass shrimp Palaemonetes pugio, a common inhabitant of brackish water marshes, is often used in experimental studies. To support studies concerned with the behavior of P. pugio in controlled laboratory conditions, a behavior catalog (or ethogram) was developed. Twelve grass shrimp activities, six moving and six stationary, were observed and described. The most frequently observed activities included hovering in the water column, walking and three types of swimming. Activities observed less often included backward thrusting, jabbing with the rostrum tip and taking cover. The value of the ethogram was assessed using a predator-prey experiment in which the frequency of grass shrimp behaviors in response the predatory fish Fundulus heteroclitus was examined. In the presence of a fish, grass shrimp decreased the frequency of swimming and increased the frequency of covered and motionless behaviors. We also noted a significant increase in the occurrence of two active antipredator defenses: backward thrust and jabbing with the rostrum tip. Backward thrust quickly propelled shrimp away from a fish. Jabbing with the rostrum tip was directed toward an advancing fish and usually caused the fish to swim off in the opposite direction. These observations provide clues as to the levels and types of interactions that occur between the grass shrimp and their fish predators in the wild. The catalog of recorded activities may be of value in future studies designed to examine the effect of different experimental conditions on grass shrimp behavior.

Larviculture output and stress tolerance of Farfantepenaeus paulensis postlarvae fed Artemia containing different fatty acids

Fatty acid nutrition is known to play a vital role on survival, growth and stress tolerance of aquatic animals. In this study, we assessed whether the enrichment of Artemia franciscana (GSL strain, USA) with emulsions containing different fatty acid profiles would affect larviculture output and tolerance to salinity, temperature and total ammonia (TAN) of the shrimp Farfantepenaeus paulensis. From mysis I up to postlarvae 10 (PL10), three replicate groups of shrimp were reared in 40-l tanks at an initial density of 60 l − 1 . They were fed one of the following diets: (1) newly hatched Artemia nauplii; (2) Artemia metanauplii enriched with a saturated fatty acid (SFA) emulsion (ICES enrichment emulsion 0/–/C); and (3) Artemia metanauplii enriched with an emulsion containing 50% n − 3 highly unsaturated fatty acids ( n − 3 HUFA) (ICES emulsion 50/0.6/C). Newly hatched Artemia nauplii were enriched for 24 h with two doses of 0.3-g emulsion per liter added at 12 h intervals. Larval feeding was carried out daily at 10:00 and 22:00 hours. Survival and total length (TL; from the tip of rostrum to the tip of the telson) were estimated. Tolerance to salinity, temperature and total ammonia (TAN; NH 4 + + NH 3) were assessed by exposing PL10 to 10‰ salinity for 1 h, 16–17 °C for 1 h and increasing total ammonia levels (0, 15, 30, 45 60 and 90 mg TAN l − 1 ) for 24 h, respectively. Tolerance to salinity and temperature were expressed as cumulative stress indexes (CSI; sum of cumulative mortalities over 1 h), while tolerance to ammonia was estimated as the median lethal concentration for 50% of the population during 24 h (LC 50). All data were subjected to ANOVA and Tukey's test, except LC 50 values, which were compared graphically. Survival of shrimp fed n − 3 HUFA-enriched Artemia was significantly higher than in the other treatments. TL of PL1 was not significantly different, but PL10 fed Artemia nauplii were significantly longer. No differences were found in terms of tolerance to salinity and temperature. PL10 fed n − 3 HUFA enriched Artemia presented a higher tolerance to ammonia. Results indicate that feeding n − 3 HUFA-enriched Artemia to F. paulensis larvae increases survival and tolerance to ammonia, which may be advantageous under adverse rearing conditions.

Threatened Fishes of the World: Acipenser nudiventris Lovetsky, 1828 (Acipenseridae)

D 39-57, A 23-37 rays, dorsalscutes 11–17, lateral scutes 49–74 and ventral scutes 11–17. Body elongated with greatest depth occurring at first dorsalscute which is unusually large in relation to other scutes. Rostrum rounded and perfectly conical in shape in adultsbut somewhat more spatulate in juveniles, usually 32–44% of head length. Two pairs of fimbrated barbels, originatingslightly closer to mouth than tip of rostrum. Mouth inferior with upper lip barely indented and unlike any acipenserid,lower lip uninterrupted. Pectoral fins are large with strongly ossified leading edge. Adults have a peppering of smalldenticles covering their body but it is so fine as to give a smooth overall appearance and feels sand paper-like to thetouch. Scutes lack a prominent hook appendage, even in juveniles it is barely noticeable. Lateral scutes tightly arrangedand seem small compared to other acipenserids except

Retention of Coded Wire Tags in Four Locations in Juvenile Paddlefish

Abstract One hundred eighty juvenile paddlefish Polyodon spathula (mean total length, 240 mm) were tagged with coded wire tags in either the midrostrum, rostrum tip, dorsal fin, or opercular flap. Mean tagging times were significantly longer (P ≤ 0.05) for the dorsal fin (19.3 s) and opercular flap (18.4 s) than for the midrostrum (5.1 s) and rostrum tip (6.6 s). Tag retention was checked monthly for 3 months. Mean tag retention for the rostrum tip (94.8%) and midrostrum (92.9%) was significantly higher (P ≤ 0.05) than that for the opercular flap (86.1%) or dorsal fin (67.4%), and tag retention for the opercular flap was significantly higher (P ≤ 0.05) than that for the dorsal fin. My results corroborate rostrum tagging locations recommended by the Mississippi Interstate Cooperative Resource Association.

A new species, Callianassa poorei sp. nov. (Decapoda: Crustacea: Callianassidae) from Tasmania

As part of my ongoing studies of the Callianassidae, Dr G. Poore of the Museum of Victoria, Australia, sent me four small specimens from Tasmania. These specimens, which include two ovigerous females, are closely allied to Callianassa lewtonae from the northern Great Barrier Reef, Queensland, Australia. They differ from that species because the merus of the chelipeds bears a triangular ventral lobe in the larger cheliped and a sharp ventral spine in the smaller cheliped; and the antennular peduncle is much longer than the antennal peduncle. Only Callianassa ceramica, C. arenosa, and C. australiensis have been previously recorded from Tasmanian waters.Abbreviations used are: MV, Museum of Victoria, Australia; CL, carapace length; TL, whole length of the specimen from the tip of rostrum to the end of telson; A1, antennule; A2, antenna; P, pereiopod; Plp, pleopod.

Coded Wire Tag Retention by Paddlefish at Three Implant Sites

Abstract Paddlefish Polyodon spathula, 180–250 mm in total length and reared in concrete raceways, were implanted with 1-mm-long coded wire tags to evaluate short-term (72 h) retention. Retention rates were significantly different (P < 0.01) among implant locations. Mean retention rates were: tip of rostrum, 71%; side of rostrum, 96% : underside of rostrum, 99%.

松江にきた乾燥標本アメリカウミザリガエ

Recently a good dried specimen of American Lobster, Homarus americanus is placed on show in a corner of the first floor of the Matsue Branch of the Central Bank for Agriculture and Forestry. This lobster was caught 250 sea miles off the coast of New York City by a crew of the Okuni-maru, a pelagic fishing vessel of Japan in January, 1974. The specimen is generally yellow-reddish brown coloured over the entire body, and measured 48cm from the tip of rostrum to the posterior margin of telson. The carapace is 27cm long including rostrum, and 21.5cm excluding rostrum, with the width of 15cm. The two spines furnished on the under-surface of the rostrum, the characteristic of the species, are of anomalous shape as follows: knitted together at the bases and expanded like a roundish plate as shown in the Text-fig. 2, B.

Morphology of Some Rostrum Receptors in Dysdercus spp

The rostrum tip of Dysdercus spp. bears on each side 13 sensilla. They include 10 sensilla basiconica, innervated by 3-5 neurons, one small sensillum basiconicum (innervated by two dendrites), one sensillum basiconicum with a sharp tip (innervated by three neurons) and one sensillum trichodeum (innervated by two neurons). The microstructure of the sensilla basconica indicates a contact chemoreceptive function; this conclusion is supported by preliminary electrophysiological evidence.