Large Gape Research Articles

Craniofacial biomechanics: in vivo to in silico

Craniofacial biomechanics: in vivo to in silico

Unusual kinematics and jaw morphology associated with piscivory in the poeciliid, Belonesox belizanus

Piscivory in fishes is often associated with the evolution of highly elongate jaws that achieve a large mouth opening, or gape. Belonesox belizanus, the pike killifish, has independently evolved this morphology, which is derived from short-jawed poeciliids within the Cyprinodontiformes. Using kinematic analysis of high-speed video footage, we observed a novel aspect of the elongate jaws of Belonesox; the premaxilla rotates dorsally during mouth opening, while the lower jaw rotates ventrally. Anatomical study revealed that this unusual motion is facilitated by the architecture of the premaxillomandibular ligament, prominent within cyprinodontiforms. In Belonesox, it allows force to be transferred from the lower jaw directly to the premaxilla, thereby causing it to rotate dorsally. This dorsal rotation of the premaxilla appears to be assisted by a mediolateral twisting of the maxilla during jaw opening. Twisting maxillae are found in members of the group such as Fundulus, but are lost in Gambusia. Models revealed that elongate jaws partially account for the enlarged gape, but enhanced rotation at the quadrato-mandibular joint was equally important. The large gape is therefore created by: (i) the convergent evolution of elongate jaws; (ii) enhanced jaw rotation, facilitated by loss of a characteristic cyprinodontiform trait, the lip membrane; and (iii) premaxilla rotation in a novel direction, facilitated by the retention and co-option of additional cyprinodontiform traits, the premaxillomandibular ligament and a twisting maxilla.

Why is cannibalism so rare among cultured larvae and juveniles of Pangasius djambal? Morphological, behavioural and energetic answers

The ontogenetic trajectory of Pangasius djambal resembles that of Pangasianodon hypophthalmus. At the start of exogenous feeding (48 h after hatching), larvae of P. djambal (8.5 mm TL, 4.5 mg WM) exhibit a large gape (17.5% TL), they possess long oral spines (100 µm) but no pectoral fins. However, the spines do not overhang from the mouth, and gape height never exceeds body depth, contrary to the situation in P. hypophthalmus. These differences account for why encounters between larvae of P. djambal never lead to the deadly clashes observed in P. hypophthalmus. The rarity of cannibalism in older larvae and juveniles of P. djambal originates from the combination of morphological, behavioural and energetic factors (studied during predation experiments with cannibals from 20 to 70 mm TL): (1) the negative allometry of mouth parts and positive allometry of body depth restrict the logistics of cannibalism from 84.9% TL at 10 mm TL to 56.5% TL at 40 mm TL; (2) cannibals of increasing size prefer prey that are increasingly smaller relative to the logistics of cannibalism (pref:max TL ratios of 99 and 48.5% at 10 and 40 mm TL, respectively); and (3) cannibals need high maintenance food rations (14.9% DM at 6–10 mg DM), they exhibit a rather low gross conversion efficiency (0.36 DM:DM at 6 mg DM), and gain no growth advantage over siblings fed brine shrimp nauplii ad libitum. No single factor suffices to account for the rarity of cannibalism in P. djambal, but their combination almost makes it impossible, even among fish fed submaximally.

Effects of ram speed on prey capture kinematics of juvenile Indo-Pacific tarpon, Megalops cyprinoides

We examined the effects of variation in swimming speed, or ‘ram speed’, on the feeding kinematics of juvenile Indo-Pacific tarpon, Megalops cyprinoides. Tarpon were filmed feeding on non-elusive prey at 500 images s −1. Prey items were offered at one end of the filming tank, the opposite end where tarpon grouped, to encourage them to use a ram strategy to capture their prey. We describe tarpon as ram-suction feeders. Ram speed varied among strikes from 0.19 to 1.38 m/s and each individual produced speeds that spanned at least 0.9 m/s across trials. Although suction distances were much less variable, prey movement towards the predator was present in all feeding trials. There was a strong positive relationship between initial predator – prey distance and ram speed ( r 2=0.72, P<0.001). When tarpon initiated their strike from further away, they achieved higher ram speeds, but also took longer to capture their prey. All other timing variables were unaffected by ram speed whereas at higher ram speeds tarpon exhibited greater expansion of the mouth and buccal cavity. Greater buccal expansion accomplished in the same period of time implies that both the total volume of water captured and the water flow rate entering the mouth was greater in strikes at higher ram speeds. Our results demonstrate how feeding kinematics may vary as a function of ram speed, and how fish predators that lack jaw protrusion and have a large gape capacity can maximize their feeding success by altering their swimming speed.

Glomus Tumor of the Ovary Masquerading as Granulosa Cell Tumor: Case Report

A solid right adnexal mass in a 73-year-old woman bled profusely with mobilization mimicking a granulosa cell tumor. There was almost complete replacement of the ovary by a circumscribed, 4.0 cm tumor with a hemorrhagic, solid cut surface. Morphologic and phenotypic correlation supported a diagnosis of glomus tumor. Large gaping vessels and small sinusoidal-type vessels formed an anastomotic vascular network with an inner endothelial lining (CD31+/CD34+) and an outer layer of glomocytes (actin+/desmin-/inhibin-). The hemangiopericytoma-like vasculature accounted for bleeding during surgery.

Ingestion of fishing gear and entanglements of seabirds: Monitoring and implications for management

Fisheries are increasingly adopting ecosystem approaches to better manage impacts on non-target species. Although deliberate dumping of plastics at sea is banned, not all fisheries legislation prohibits discarding of gear (hooks and line) in offal, and compliance is often unknown. Analysis of a 16 year dataset collected at South Georgia indicated that the amount of gear found in association with wandering albatrosses was an order of magnitude greater than in any other species, reflecting their wider foraging range and larger gape. Unlike other taxa, most gear associated with grey-headed albatrosses was from squid and not longline fisheries, and mistaken for natural prey rather than the result of direct interaction. Observed rates of foul-hooking (entanglement during line-hauling) were much higher in giant petrels and wandering albatrosses than black-browed albatrosses, and no grey-headed albatross was affected. The index of wandering albatross gear abundance showed two peaks, the most recent corresponding with a substantial increase in the number of multifilament snoods (gangions), suggesting that the widespread adoption of a new longline system (Chilean mixed) may have been responsible. Although all identified gear was demersal, given the widespread use of similar hooks, little could be assigned to a specific fishery. Stomach content analysis suggested that 1300–2048 items of gear are currently consumed per annum by the wandering albatross population. Many hooks are completely digested by chicks, long-term effects of which are entirely unknown. We suggest a number of management approaches for addressing the problem of gear discarding, and guidelines for monitoring schemes elsewhere.

The morphology of the masticatory apparatus facilitates muscle force production at wide jaw gapes in tree-gouging common marmosets (Callithrix jacchus)

Common marmosets (Callithrix jacchus) generate wide jaw gapes when gouging trees with their anterior teeth to elicit tree exudate flow. Closely related cotton-top tamarins (Saguinus oedipus) do not gouge trees but share similar diets including exudates. Maximizing jaw opening theoretically compromises the bite forces that marmosets can generate during gouging. To investigate how jaw-muscle architecture and craniofacial position impact muscle performance during gouging, we combine skull and jaw-muscle architectural features to model muscle force production across a range of jaw gapes in these two species. We incorporate joint mechanics, resting sarcomere length and muscle architecture estimates from the masseter and temporalis to model muscle excursion, sarcomere length and relative tension as a function of joint angle. Muscle excursion from occlusion to an estimated maximum functional gape of 55 deg. was smaller in all regions of the masseter and temporalis of C. jacchus compared with S. oedipus except the posterior temporalis. As a consequence of reduced muscle excursion distributed over more sarcomeres in series (i.e. longer fibers), sarcomere length operating ranges are smaller in C. jacchus jaw muscles across this range of gapes. This configuration allows C. jacchus to act on a more favorable portion of the length-tension curve at larger gapes and thereby generate relatively greater tension in these muscles compared with S. oedipus. Our results suggest that biting performance during tree gouging in common marmosets is improved by a musculoskeletal configuration that reduces muscle stretch at wide gapes while simultaneously facilitating comparatively large muscle forces at the extremes of jaw opening.

Gape and bite force in the rodents Onychomys leucogaster and Peromyscus maniculatus: Does jaw‐muscle anatomy predict performance?

Compared with the deer mouse, Peromyscus maniculatus, the grasshopper mouse, Onychomys leucogaster, exhibits modifications in its jaw-muscle architecture that promote wide gapes and large bite forces at wide gapes to prey upon large vertebrate prey. In this study, we determine whether jaw-muscle anatomy predicts gape and biting performance in O. leucogaster, and we also assess the influence of gape on bite force in the two species. Although O. leucogaster has an absolutely longer jaw, which facilitates larger gapes, maximum passive gape is similar in both species, averaging approximately 12.5 mm. Thus, when scaled to jaw length, O. leucogaster has a smaller maximum passive gape. These results suggest that predatory behaviors of O. leucogaster may not require remarkably large gapes. On the other hand, both absolute and relative bite forces exerted by O. leucogaster are significantly larger than those of P. maniculatus. The largest bite forces in both species occur at 5.0 mm of gape at the incisors, or 40% of maximum gape. Although bite force in both species decreases at larger gapes, O. leucogaster does maintain a larger percentage of maximum bite force at gapes larger than 40% of maximum passive gape. Therefore, although structural modifications in the masticatory apparatus of O. leucogaster may constrain gape, they may help to maintain bite force at large gapes. These results suggest that increases in gape differentially influence the length-tension properties of the jaw muscles in the two species. Finally, these results highlight the importance of considering the effect of muscle stretch on force production in comparative studies of bite force. As a first approximation, it appears that gapes of 40-50% of maximum gape in rodents optimizes bite force production at the incisors.

The evolution of the lepidosaurian lower temporal bar: new perspectives from the Late Cretaceous of South China

Until recently, it was considered axiomatic that the skull of lizards and snakes arose from that of a diapsid ancestor by loss of the lower temporal bar. The presence of the bar in the living New Zealand Tuatara, Sphenodon, was thus considered primitive, corroborating its status as a ‘living fossil’. A combination of new fossils and rigorous phylogeny has demonstrated unequivocally that the absence of the bar is the primitive lepidosaurian condition, prompting questions as to its function. Here we describe new material of Tianyusaurus, a remarkable lizard from the Late Cretaceous of China that is paradoxical in having a complete lower temporal bar and a fixed quadrate. New material from Jiangxi Province is more complete and less distorted than the original holotype. Tianyusaurus is shown to be a member of the Boreoteiioidea, a successful clade of large herbivorous lizards that were dispersed through eastern Asia, Europe and North America in the Late Cretaceous, but disappeared in the end-Cretaceous extinction. A unique combination of characters suggests that Tianyusaurus took food items requiring a large gape.

Passive versus active engulfment: verdict from trajectory simulations of lunge-feeding fin whalesBalaenoptera physalus

Lunge-feeding in rorqual whales represents the largest biomechanical event on Earth and one of the most extreme feeding methods among aquatic vertebrates. By accelerating to high speeds and by opening their mouth to large gape angles, these whales generate the water pressure required to expand their mouth around a large volume of prey-laden water. Such large influx is facilitated by highly extensible ventral groove blubber (VGB) associated with the walls of the throat (buccal cavity). Based on the mechanical properties of this tissue, previous studies have assumed lunge-feeding to be an entirely passive process, where the flow-induced pressure driving the expansion of the VGB is met with little resistance. Such compliant engulfment would be facilitated by the compliant properties of the VGB that have been measured on dead specimens. However, adjoining the ventral blubber are several layers of well-developed muscle embedded with mechanoreceptors, thereby suggesting a capability to gauge the magnitude of engulfed water and use eccentric muscle action to control the flux of water into the mouth. An unsteady hydrodynamic model of fin whale lunge-feeding is presented here to test whether engulfment is exclusively passive and compliant or involves muscle action. The model is based on the explicit simulation of the engulfed water as it interacts with the buccal cavity walls of the whale, under different heuristically motivated cavity forces. Our results, together with their comparison with velocity data collected in the field, suggest that adult rorquals actively push engulfed water forward from the very onset of mouth opening in order to successfully complete a lunge. Interestingly, such an action involves a reflux of the engulfed mass rather than the oft-assumed rebound, which would occur mainly at the very end of a lunge sequence dominated by compliant engulfment. Given the great mass of the engulfed water, reflux creation adds a significant source of hydrodynamic drag to the lunge process, but with the benefit of helping to circumvent the problem of removing prey from baleen by enhancing the efficiency of cross-flow filtration after mouth closing. Reflux management for a successful lunge will therefore demand well-coordinated muscular actions of the tail, mouth and ventral cavity.

Measurements of Lacrimal Glands from Cadavers, With Descriptions of Typical Glands and Three Gross Variants

Objective: To measure cadaveric human lacrimal glands. Methods: Excised lacrimal glands from 22 male and 23 female embalmed cadavers were stored in embalming fluid. They were then blotted, weighed, and measured using dividers and a digital micrometer. Results: Besides the typical gland (Type I), three gross variants were found. The subencapsulated variant (Type II) has dense connective tissue covering its deep surface. This would prevent the usual horizontal positioning of the lobes relative to the levator palpebrae superioris aponeurosis (lpsa), causing the latter to extend but minimally beneath the free edge of the orbital lobe. Consequently, the gland lies mainly beside the globe and angulated parallel to the lpsa. Its adjacent palpebral lobe lies beneath the latter. The bilayered variant (Type III) has its smaller orbital lobe's deep surface affixed above its large, ovoid palpebral lobe. Most of the gland droops beside the globe except for the edge of its orbital lobe which lies above the edge of the lpsa and beneath which the palpebral lobe's anteromedial portion lies. The macrovariant (Type IV) resembles the typical gland. However, between its big lobes is an unusually large gape for the lpsa. Conclusions: Variant lacrimal glands are common (51.1%). Three types have been identified. The subencapsulated (26.7%) and bilayered (22.2%) types are the more common ones. Only one macrovariant (2.2%) specimen was found. Several dimorphisms exist in the typical and subencapsulated types, specimens from male cadavers being larger.

Gerrothorax pulcherrimus from the Upper Triassic Fleming Fjord Formation of East Greenland and a reassessment of head lifting in temnospondyl feeding

ABSTRACT The plagiosaurine Gerrothorax pulcherrimus, a ubiquitous faunal component of the Fleming Fjord Formation, is recognized by tubercular ornamentation, contact between the postfrontal and supratemporal, at least two tooth rows on the posterior coronoid, and a posttemporal fenestra that is small or absent. Gerrothorax pulcherrimus also possesses a derived pectoral morphology that includes an interlocking claviculocleithral complex and an interclavicle with paired posterolateral projections and a transversely truncated posterior margin. Gerrothorax pustuloglomeratus is a junior synonym of G. pulcherrimus; other Gerrothorax species cannot be differentiated from G. pulcherrimus. Flat-headed temnospondyls have been interpreted as having achieved a large gape by raising the skull rather than by lowering the jaw. No detailed, corroborating anatomical evidence from the atlanto-occipital joint, however, has ever been adduced. In G. pulcherrimus the widths of the atlantal and condylar facets are comparable, but dorsoventrally the condylar facets are 45% longer than the comparable dimension of the atlantal facets. Elevation of the skull occurred by atlanto-occipital rotation, and was facilitated by a radius of curvature of the dorsal part of the condylar facets that is shorter than that of the inferior part. From a resting, closed mouth position, G. pulcherrimus was capable of elevating the skull through an excursion of approximately 50°, a movement that rotated the quadrate forward and protruded the lower jaw. An elongate, broadly open neural canal in the atlanto-occipital region, and dorsal displacement of the occipital condyles, are related to relieving the spinal medulla of the sharp angular deformation that head lifting might entail.

Suicide by a circular saw

The case of a suicide of a 32-year-old female using an electric circular saw is herein described. The decedent was suffering from depression and was found dead in her room. Beside her right hand was lying a circular saw, which was not running. The autopsy revealed a large gaping wound measuring 15.5 cm in length on the right side of her neck. The right external carotid artery, the right internal jugular vein, and the right internal carotid artery were cut and the injury reached to the cervical vertebra. Therefore, the cause of death was exsanguination. An individual who commits suicide with an electric saw, such as a chain saw, band saw, and circular saw is rare; in particular females rarely select this method as the means of suicide. However, we herein report the case of a female patient with a psychiatric disease who successfully committed suicide with a circular saw.

Habitat-dependent reduction of sexual dimorphism in geometric body shape of Haida Gwaii threespine stickleback

We investigated the extent of sexual dimorphism in body shape in adult threespine stickleback (Gasterosteus aculeatus) from 39 lakes, eight streams, and five marine (two brackish, three full marine) localities on the Haida Gwaii archipelago off the mid-coast of British Columbia, as well as three lakes from southern British Columbia with benthic–limnetic species pairs. Based on digital images of 709 males and 593 females, body shape was quantified using discriminant function analysis on partial warp scores generated from twelve homologous landmarks. All populations showed males with higher positive values for canonical vector 1, which are characterized by larger heads, larger gape, posteriad dorsal spines, posteriad pelvis, longer anal fin, and deep posterior caudal depth relative to those in females. Geographical variability was present, with the highest dimorphism occurring in two of the marine habitats in addition to large lakes, whereas reduced dimorphism occurs in small shallow dystrophic ponds. We suggest that this reduction is the derived condition and is primarily due to loss of niche breadth and convergence in body shape between the sexes in pond habitats. Analyses of two experimental pond populations indicate that up to 15% of the shape dimorphism can be attributed to habitat-induced phenotypic plasticity. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95, 505–516.

Feeding kinematics, suction and hydraulic jetting capabilities in bearded seals (Erignathus barbatus)

Feeding kinematics, suction and hydraulic jetting capabilities of bearded seals (Erignathus barbatus) were characterized during controlled feeding trials. Feeding trials were conducted both on land and in water, and allowed a choice between suction and biting, but food was also presented that could be ingested by suction alone. Four feeding phases, preparatory, jaw opening, hyoid depression and jaw closing were observed; the mean feeding cycle duration was 0.54+/-0.22 s, regardless of feeding mode (P>0.05). Subjects feeding on land used biting and suction 89.3% and 10.7% of the time, respectively. Subjects feeding in water used suction and hydraulic jetting 96.3% and 3.7% of the time, respectively. No biting behavior was observed underwater. Suction feeding was characterized by a small gape (2.7+/-0.85 cm), small gape angle (24.4+/-8.13 degrees ), pursing of the rostral lips to form a circular aperture, and pursing of the lateral lips to occlude lateral gape. Biting was characterized by large gape (7.3+/-2.2 cm), large gape angle (41.7+/-15.2 degrees ), and lip curling to expose the teeth. An excavation behavior in which suction and hydraulic jetting were alternated was used to extract food from recessed wells. The maximum subambient and suprambient pressures recorded were 91.2 and 53.4 kPa, respectively. The inclusion of suction data for phocids broadens the principle that suction feeding kinematics is conserved among aquatic vertebrates. Furthermore, bearded seals support predictions that mouth size, fluid flow speed, and elusiveness of prey consumed are among a suite of traits that determine the specific nature of suction feeding among species.

A functional comparison of the hyolingual complex in pygmy and dwarf sperm whales (Kogia breviceps and K. sima), and bottlenose dolphins (Tursiops truncatus)

The function of the hyolingual complex in three odontocete species was investigated to compare adaptations of divergent feeding strategies, suction and ram feeding. Pygmy and dwarf sperm whales, members of the genus Kogia (or kogiids), are known to be strong suction feeders. We tested the hypotheses that kogiids would have a larger, more robust hyolingual complex, and that hyolingual muscles would have a greater maximum theoretical muscle tension compared with ram-based feeders such as bottlenose dolphins (Tursiops truncatus). A robustness index and surface area was calculated for bony hyoid elements in kogiids and bottlenose dolphins. The anatomy, muscle architecture, pinnation, two-dimensional angle of attachment and maximum theoretical muscle tension were measured in each hyolingual muscle. A functional model incorporating vector analyses of hyolingual musculature was created for kogiids and bottlenose dolphins to assess differences in function of their hyolingual complexes. Kogiid hyoid surface areas were significantly greater (P = 0.01) than in bottlenose dolphins. Most maximum theoretical muscle tensions of hyolingual complexes were not significantly different within or between species. The data suggest that associated orofacial and tongue morphology, particularly the relationship of hyoid shape and tongue retractor muscles, greatly influences suction capability in odontocetes. Kogiids demonstrated adaptations that occlude lateral gape, including a novel vertical ridge on each side of the mandible, and a shortened mandible that is capable of a large gape, and gape angle. These adaptations presumably assist in maintaining negative intraoral pressure generated by the depression and retraction of the relatively short and wide kogiid tongue. The tongues of kogiids should be capable of generating greater intraoral volume changes compared with the long, narrow tongue of bottlenose dolphins.

Evolution and ecology of feeding in elasmobranchs

Paleozoic chondrichthyans had a large gape, numerous spike-like teeth, limited cranial kinesis, and a non-suspensory hyoid, suggesting a feeding mechanism dominated by bite and ram. Modern sharks are characterized by a mobile upper jaw braced by a suspensory hyoid arch that is highly kinetic. In batoids, the upper jaw is dissociated from the cranium permitting extensive protrusion of the jaws. Similar to actinopterygians, the evolution of highly mobile mandibular and hyoid elements has been correlated with extensive radiation of feeding modes in elasmobranchs, particularly that of suction. Modern elasmobranchs possess a remarkable variety of feeding modes for a group containing so few species. Biting, suction or filter-feeding may be used in conjunction with ram to capture prey, with most species able to use a combination of behaviors during a strike. Suction-feeding has repeatedly arisen within all recent major elasmobranch clades and is associated with a suite of morphological and behavioral specializations. Prey capture in a diverse assemblage of purported suction-feeding elasmobranchs is investigated in this study. Drop in water pressure measured in the mouth and at the location of the prey shows that suction inflow drops off rapidly with distance from the predator's mouth. Elasmobranchs specializing in suction-feeding may be limited to bottom associated prey and because of their small gape may have a diet restricted to relatively small prey. Behavior can affect performance and overcome constraints imposed by the fluid medium. Suction performance can be enhanced by proximity to a substrate or by decreasing distance from predator to prey using various morphological and/or behavioral characteristics. Benthic suction-feeders benefit by the increased strike radius due to deflection of water flow when feeding close to a substrate, and perhaps require less accuracy when capturing prey. Suction and ram-suction-feeding elasmobranchs can also use suction inflow to draw prey to them from a short distance, while ram-feeding sharks must accelerate and overtake the prey. The relationship between feeding strategy and ecology may depend in part on ecological, mechanistic or evolutionary specialization. Mechanistic suction-feeding specialist elasmobranchs are primarily benthic, while most epibenthic and pelagic elasmobranchs are generalists and use ram, suction, and biting to catch a diversity of prey in various habitats. Some shark species are considered to be ecological specialists in choosing certain kinds of prey over others. Batoids are evolutionary specialists in having a flattened morphology and most are generalist feeders. Filter-feeding elasmobranchs are ecological, mechanistic, and evolutionary specialists.

Endoluminal suturing may overcome the limitations of clip closure of a gaping wide colon perforation (with videos)

It is unclear whether large gaping perforations of the colon can be closed by the endoluminal route. To evaluate the feasibility and the outcome of closure of large perforations of colon with clips and sutures by using through-the-endoscope novel devices. Prospective animal study. University hospital. Ten pigs. Closure of a 4-cm full-thickness colon perforation freshly created by an insulated-tip knife with the InScope Multi-Clip Applier (n = 6) and with the tissue approximation device (n = 4). (a) Technical feasibility of closure, (b) clinical monitoring for 2 weeks, (c) necropsy (day 14), (d) healing by a dye-leak test and histology. Endoluminal closure of a 4-cm-long colon perforation was successful in 9 of 10 animals. The clips failed to close a gaping wide colon perforation in 1 animal. The sutures were successful in the closure of both nongaping and gaping perforations. Successful closure resulted in a leakproof sealing at 2 weeks and prevented clinical peritonitis in all the animals in the clip-closure group and in 3 of 4 animals in the suture-closure group. Necropsy at 2 weeks revealed mild peritonitis in 2 of the 5 animals in the clip closure group and in 2 of the 4 animals in the suture-closure group; none developed fecal peritonitis. None. Endoluminal closure of a 4-cm colon perforation with clips was successful in the majority of cases. Sutures were useful in the closure of gaping colon perforations that could not be closed with clips.

The effects of zooplankton swimming behavior on prey-capture kinematics of red drum larvae, Sciaenops ocellatus

Most marine fishes undergo a pelagic larval phase, the early life history stage that is often associated with a high rate of mortality due to starvation and predation. We present the first study that examines the effects of prey swimming behavior on prey-capture kinematics in marine fish larvae. Using a digital high-speed video camera, we recorded the swimming velocity of zooplankton prey (Artemia franciscana, Brachionus rotundiformis, a ciliate species, and two species of copepods) and the feeding behavior of red drum (Sciaenops ocellatus) larvae. From the video recordings we measured: (1) zooplankton swimming velocity in the absence of a red drum larva; (2) zooplankton swimming velocity in the presence of a red drum larva; and (3) the excursion and timing of key kinematic events during prey capture in red drum larvae. Two-way ANOVA revealed that: (1) swimming velocity varied among zooplankton prey; and (2) all zooplankton prey, except rotifers and ciliates, increased their swimming velocity in the presence of a red drum larva. The kinematics of prey capture differed between two developmental stages in S. ocellatus larvae. Hyoid-stage larvae (3–14 days old) fed on slow swimming B. rotundiformis (rotifers) while hyoid-opercular stage larvae (15 days and older) ate fast moving A. franciscana. Hyoid-opercular stage red drum larvae had a larger gape, hyoid depression and lower jaw angle, and a longer gape cycle duration relative to their hyoid-stage conspecifics. Interestingly, the feeding repertoire within either stage of red drum development was not affected by prey type. Knowledge of the direct relationship between fish larvae and their prey aids in our understanding of optimal foraging strategies and of the sources of mortality in marine fish larvae.

Trophic ecomorphology of cardinalfish

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 322:249-257 (2006) - doi:10.3354/meps322249 Trophic ecomorphology of cardinalfish Adam Barnett1,2,*, David R. Bellwood1, Andrew S. Hoey1 1Centre for Coral Reef Biodiversity, School of Marine Biology, James Cook University Townsville, Queensland 4811, Australia 2Present address: Marine Research Laboratories, Nubeena Crescent, Taroona, Tasmania 7053, Australia *Email: yatanka29@hotmail.com ABSTRACT: Trophic diversity in 9 cardinalfish species was investigated by comparing 14 morphological characteristics of their feeding apparatus with dietary data based on stomach content analysis. Analysis of the morphological characteristics separated the 9 species into 3 distinct groups. The first group (Cheilodipterus macrodon, C. artus and C. quinquelineatus) was characterized by elongated heads; the second group (Archamia fucata, Apogon guamensis, A. cyanosoma and A. fragilis) by large gapes; and the third group (Apogon exostigma, A. doederleini) by wider heads and low transmission coefficient in their jaw mechanics. Stomach samples, however, revealed that morphology was of limited utility in predicting dietary groupings. The majority of species examined displayed generalist diets. The results indicate that while morphology may predict feeding potential, or feeding mode, actual resource use in this group may be shaped primarily by other modifying factors such as behaviour and prey availability. In contrast to other reef fish groups, morphology does not appear to play a strong role in influencing diet in the Apogonidae. KEY WORDS: Coral reef · Diet · Apogonidae · Trophic ecomorphology · Functional morphology Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 322. Online publication date: September 20, 2006 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2006 Inter-Research.