Captive parturition and neonatal growth of the dwarf ornate wobbegong (Orectolobus ornatus de Vis, 1883)

Neonatal predation in multispecies aquarium exhibits can prevent detection of captive breeding by wobbegong sharks. We used ultrasonography and isolation strategies to prevent neonatal predation and maximize survival/growth of the dwarf ornate wobbegong (Orectolobus ornatus de Vis, 1883). We captured seven free‐living wobbegongs (two males and five females) and subjected each animal to a health assessment which led to the euthanasia of one female with a retained hook. Ultrasonography showed that females were pregnant, one was preovulatory, and one was in a resting phase. Two females (one pregnant) and one male were placed in isolation in each of two tanks. In October 2006, 25 neonates were born overnight with the two litters placed into separate neonate tanks. Over the ～6.5‐month monitoring period, four neonates with reduced body condition died without premonitory signs resulting in a 63.0% annual survival rate. Finite growth rates did not differ between sexes or litters and averaged (±SE) 12.2 (1.5) cm/year and 156.4 (26.4) g/year. At the cessation of monitoring, total length had increased by ～30%, whereas total weight had almost doubled with neonatal body condition in line with free‐living wobbegongs. Our efficacious, six‐step manipulative, the approach should be applicable with all wobbegongs given their reproductive similarities, but we recommend that efforts focus on the dwarf ornate, tasselled and Japanese wobbegongs because all are small in size and have bred in aquaria. Ultimately, this approach should produce self‐sustaining aquarium populations, place less reliance on the wild acquisition and provide animals for other aquaria, population restocking, or scientific research.     

Genetic and reproductive evidence for two species of ornate wobbegong shark Orectolobus spp. on the Australian east coast

This study reports on evidence for reproductive isolation among Orectolobus ornatus and Orectolobus halei, two previously cryptic and recently redescribed species of wobbegong shark (Orectolobiformes: Orectolobidae) from the east coast of Australia. The evidence is based on disparity in size at sexual maturity, diagnostic nuclear and mitochondrial DNA variants, and marked phylogenetic divergence. Plots of total length (L_T) and maturity for the two species were non‐overlapping and illustrative of statistically significant size dimorphism. Genetic analyses and phylogenetic reconstruction did not provide indication of hybridization between O. ornatus and O. halei. In fact, sequence divergence between them was higher than in comparisons with another congeneric and largely co‐distributed wobbegong species (Orectolobus maculatus). The assumption of a molecular clock revealed that the two species have evolved in isolation for c. 3·9 million years. These results challenge a paradigm often mentioned in the biodiversity literature that most cryptic species are the product of recent speciation events and will contribute to the development of effective management strategies for wobbegong sharks.     

Changes in Composition During Embryo Development of the Gulper Shark,Centrophorus Granulosus (Elasmobranchii,Centrophoridae): An Assessment of Maternal-embryonic Nutritional Relationships

Centrophorus granulosus is a deep sea shark that reproduces through aplacental viviparity. Its fecundity is one of the lowest described with only one embryo in a pregnancy lasting about two years. Its mature ovarian egg reaches one of the largest cellular sizes (> 350g) described for any animal species. A previous report suggested a loss of organic matter during development of about 50% (Ranzi 1932), the highest rate reported for any elasmobranch. We measured the amounts of water, organic and inorganic matter in a complete series of embryos, by drying and later incinerating separately the external yolksac, eviscerated body, internal yolksac, liver and digestive tract. Wet weight of uterine ova ranged from 143.2–370.4g, was positively and significantly correlated with maternal size, and the size of full-term embryos increased with maternal size. A graphical method was developed to allow weight comparison between uterine ova and full-term embryos while taking into account the initial variability in uterine ova size. Total wet weight of the embryo system increased during development by +31/+34%. Changes in percentage composition (from initial values) were: water +99/+101%; organic matter –18/–25%; inorganic matter +114/+170%. The rate of decrease of organic matter was much lower than previously suggested, and was similar to values described for oviparous species. These results suggest that C. granulosus is a strictly lecithotrophic species, with no maternal contribution of organic matter during development, although the female does provide both water and inorganic material. Other factors that might influence the accuracy of this assessment are discussed.     

Quantification of the maternal-embryonal nutritional relationship of elasmobranchs: case study of wobbegong sharks (genus Orectolobus)

The present study used wobbegong sharks (genus Orectolobus) to assess the threshold value proposed by previous research to categorize strict lecithotrophic from incipient histotrophic species. Totals of 236 and 135 ornate wobbegong Orectolobus ornatus and spotted wobbegong Orectolobus maculatus, respectively, were collected from the New South Wales commercial fishery between June 2003 and May 2006. Eight pregnant gulf wobbegong Orectolobus halei were also recorded outside the sampling period for the first time. The three species were reproductively synchronous with a gestation of c. 10-11 months. Embryos started to be macroscopically visible during January and external yolk sacs were fully absorbed by June to July when embryos were c. 200 mm total length (L(T) ). Internal yolk sacs were first observed during April to May when embryos were c. 160 mm L(T) , reached a peak during June and persisted in embryos immediately prior to parturition. The total wet mass from uterine egg to full-term embryos increased by 44-89% and 45-62%, whereas the total organic mass decreased by 32-33% and 26%, for O. ornatus and O. maculatus, respectively, suggesting that these species are strict lecithotrophic yolk-sac viviparous sharks with no maternal nutrient input. A review of the literature identified various issues and suggested that the previously proposed organic mass loss threshold value separating strict lecithotrophic species from incipient histotrophic species might not be appropriate. Instead, it is recommended that a combination of methods (e.g. estimation of organic mass gain or loss between ovarian egg and developed embryo, histology and electron microscopy of the uterus, radio-tracer assay and uterine fluid analysis throughout gestation) is used to discern between strict lecithotrophic and incipient histotrophic species.     

Performance of shark teeth during puncture and draw: implications for the mechanics of cutting

The performance of an organism's feeding apparatus has obvious implications for its fitness and survival. However, the majority of studies that focus on chondrichthyan feeding have largely ignored the role of teeth. Studying the functional morphology of shark teeth not only elucidates the biological role that teeth play in feeding, but also provides insight specifically into the evolution of shark feeding because teeth are often the only structures available in the fossil record. In the present study, we investigate the puncture and draw performance of three general categories of extant teeth, tearing‐type, cutting‐type, and cutting–clutching type, as well as three fossil morphologies, utilizing a universal testing system. Differences in puncturing performance occurred among different prey items, indicating that not all ‘soft’ prey items are alike. The majority of teeth were able to puncture different prey items, and differences in puncture performance also occurred among tooth types; however, few patterns emerged. In some cases, broader triangular teeth were less effective at puncturing than narrow‐cusped teeth. There were no differences between the maximum draw forces and maximum puncture forces. Many of the shark teeth in the present study were not only able to perform draw and puncture equally well, but also many tooth morphologies were functionally equivalent to each other. The findings obtained in the present study lend little support to the belief that shark tooth morphology is a good predictor of biological role. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 271–286.     

Morphology of the blood cells from three species of wobbegong sharks (Orectolobus species) on the east coast of New South Wales

This study is the first study to describe blood cell morphology, using light microscopy, for three species of wild‐caught wobbegong shark. Blood cell morphology was similar to that described previously in fish. Wobbegong sharks possess erythrocytes, at least three different morphological types of thrombocytes, lymphocytes, eosinophils, neutrophils, granuloblasts and monocytes. No basophils were observed in this study. Similarities and differences in morphological appearance of wobbegong shark blood cells compared to Chondrichthyes, teleosts and mammalian blood cells are discussed. Zoo Biol 0:1–10, 2005. © 2005 Wiley‐Liss, Inc.     

Internal embryonic brooding and development in the southern Australian micro-snail Tricolia rosea (Angas, 1867) (Vetigastropoda: Phasianellidae: Tricoliinae)*

ABSTRACT

Internal embryonic brooding has been suggested as an adaptation to enhance reproductive success in minute gastropods. It is rare in vetigastropods, previously known in only two species of Spectamen Iredale, 1924 (Solariellidae) from South Africa. Herein it is confirmed in the temperate Australian micro-snail Tricolia rosea (Angas, 1867), with up to 46 embryos observed within a gravid female. Embryos are brooded to an advanced stage, possessing a translucent, calcified shell and a calcified operculum. The initial protoconch is colourless, spirally sculptured and delineated by a consistent axial demarcation at the 0.75 whorl mark, when it measures 320?µm across. Beyond this, the second part of the protoconch is tinted pink, the strong spiral sculpture continues but the ribs and interstices are broader, with smoother surface microsculpture. At the 1.1 to 1.125 whorl mark the protoconch measures 400?µm across when transition to smooth teleoconch sculpture occurs. No brooded embryos possessed teleoconch sculpture. The potential relationship of protoconch morphology to embryonic development, hatching, feeding and release are considered. The mechanism of fertilisation is unknown, but embryos in a brood are at the same developmental stage. Unanswered questions in embryonic development and problems with protoconch terminologies in vetigastropods are also discussed.     

Tripartite genetic subdivisions in the ornate shrew (Sorex ornatus)

We examined cytochrome b sequence variation in 251 ornate shrews (Sorex ornatus) from 20 localities distributed throughout their geographical range. Additionally, vagrant (S. vagrans) and montane (S. monticolus) shrews from four localities were used as outgroups. We found 24 haplotypes in ornate shrews from California (USA) and Baja California (Mexico) that differed by 1-31 substitutions in 392 bp of mitochondrial DNA (mtDNA) sequence. In a subset of individuals, we sequenced 699 bp of cytochrome b to better resolve the phylogeographic relationships of populations. The ornate shrew is phylogeographically structured into three haplotype clades representing southern, central and northern localities. Analysis of allozyme variation reveals a similar pattern of variation. Several other small California vertebrates have a similar tripartite pattern of genetic subdivision. We suggest that topographic barriers and expansion and contraction of wetland habitats in the central valley during Pleistocene glacial cycles account for these patterns of genetic variation. Remarkably, the northern ornate shrew clade is phylogenetically clustered with another species of shrew suggesting that it may be a unique lowland form of the vagrant shrew that evolved in parallel to their southern California counterparts.     

Uterine epithelial cell changes during pregnancy in a marsupial (Sminthopsis crassicaudata; Dasyuridae)

Formation of a placenta requires intimate contact between the embryonic and maternal uterine epithelia in early pregnancy. Contact is accompanied by a characteristic suite of changes to the plasma membranes of uterine epithelial cells, termed the plasma membrane transformation. The plasma membrane transformation occurs in eutherian mammals and in viviparous (live‐bearing) squamate reptiles, and may be fundamental to the evolution of viviparity in amniotes. Marsupials provide an excellent opportunity to test the generality of this phenomenon. Here, we present the first detailed study of the plasma membrane transformation in a marsupial. We combine electron microscopy and immunohistochemistry to describe morphological and molecular features of uterine epithelial cells during pregnancy in the fat‐tailed dunnart (Sminthopsis crassicaudata; Dasyuridae). Cell morphology changes dramatically in S. crassicaudata during pregnancy. Apical microvilli are replaced by irregular blunt projections, then by spiky projections postimplantation. Cell surfaces flatten and ciliated cells are lost. Junctional complexes between adjacent cells increase in depth, then decrease just before implantation, which is consistent with junctional protein localization in this region of the cell membrane. The uterine cellular changes in S. crassicaudata are consistent with a plasma membrane transformation, and support the idea that this phenomenon is fundamental to the evolution of viviparity in amniote vertebrates. J. Morphol. 275:1081–1092, 2014. © 2014 Wiley Periodicals, Inc.     

Composition of uterine milk and its changes with gestational period in red stingrays (Hemitrygon akajei)

Uterine milk is secreted in the uterus for embryo nutrition in several elasmobranch species and may contribute to rapid embryonic growth, but the details of its composition and its functions are poorly understood. In this study, to explore the roles of uterine milk for embryos, its components throughout the gestational period were analysed in detail. Uterine milk was collected from pregnant red stingrays (Hemitrygon akajei) in the early, middle and late gestational periods, respectively (n= 3 for each period). The crude composition, constituent proteins and fatty acids in the milk were analysed. The uterine milk was rich in proteins throughout the gestational period, whereas lipids dramatically increased in the middle period and reduced slightly towards the late period. Some proteins potentially associated with nutrition, cartilage growth and embryonic immunity were found. Several enzymes related to central metabolism were also detected. The constituent fatty acids in the middle and late periods were similar to those in the egg yolks of elasmobranchs, except for C18:2, which was rich only in the uterine milk. The most abundant fatty acid in the milk was C16:1, which could function as a lipokine to promote lipid metabolism in the embryo. This study's data suggest that uterine milk may be secreted in addition to the egg yolk in elasmobranchs to support rapid and healthy embryonic growth.     

An examination of surface epithelium structures of the embryo across the genus Poeciliopsis (Poeciliidae)

In viviparous, teleost fish, with postfertilization maternal nutrient provisioning, embryonic structures that facilitate maternal‐fetal nutrient transfer are predicted to be present. For the family Poeciliidae, only a handful of morphological studies have explored these embryonic specializations. Here, we present a comparative morphological study in the viviparous poeciliid genus, Poeciliopsis . Using microscopy techniques, we examine the embryonic surface epidermis of Poeciliopsis species that vary in their level of postfertilization maternal nutrient provisioning and placentation across two phylogenetic clades and three independent evolutionary origins of placentation. We focus on surface features of the embryo that may facilitate maternal‐fetal nutrient transfer. Specifically, we studied cell apical‐surface morphology associated with the superficial epithelium that covers the body and sac (yolk and pericardial) of embryos at different developmental stages. Scanning electron microscopy revealed common surface epithelial cells across species, including pavement cells with apical‐surface microridges or microvilli and presumed ionocytes and/or mucus‐secreting cells. For three species, in the mid‐stage embryos, the surface of the body and sac were covered in microvillus epithelium. The remaining species did not display microvillus epithelium at any of the stages examined. Instead, their epithelium of the body and sac were composed of cells with apical‐surface microridges. For all species, in the late stage embryos, the surface of the body proper was composed of apical‐surface microridges in a “fingerprint‐like arrangement.” Despite the differences in the surface epithelium of embryos across Poeciliopsis species and embryonic developmental stages, this variation was not associated with the level of postfertilization maternal nutrient provisioning. We discuss these results in light of previous morphological studies of matrotrophic, teleost fish, phylogenetic relationships of Poeciliopsis species, and our earlier comparative microscopy work on the maternal tissue of the Poeciliopsis placenta.     

Novel reproductive modes in freshwater clams: brooding and larval morphology in Southeast Asian taxa of Corbicula (Mollusca, Bivalvia, Corbiculidae)

While the majority of marine bivalves are oviparous, the two freshwater families among the order Veneroida, i.e. Corbiculidae and Sphaeriidae, comprise species with ovoviviparous and viviparous reproduction. Within the Corbiculidae, the genus Corbicula, which is well‐known for its invasive and, thus, ecologically important representatives, is characterized by (i) a wide range of limnic habitats, inhabiting both brackish water and freshwater environments, and (ii) contrasting modes of reproduction, including ‘planktonic’ development via a free‐swimming larva vs. intrabranchial incubation (brooding) of shelled juveniles. The present investigation of five species of Corbicula from the Indonesian islands Sumatra and Sulawesi, which were hitherto not studied anatomically, adds to the diversity in reproductive patterns in this genus. As a unique feature among Corbicula we here report on two newly observed modes of brooding in species endemic to Sulawesi, (i) tetragenous brooding (i.e. in both demibranchs) in Corbicula possoensis Sarasin & Sarasin, 1898 from Lake Poso, and (ii) prolonged incubation in the maternal gills, with juvenile shells reaching up to 1.3 mm in length and with a well‐developed hinge in C. linduensis Bollinger, 1914 from the Lindu River system. In contrast, a third method is seen in the following taxa that incubate their young in their inner demibranchs only until the stage of juveniles with straight‐hinged shells (D‐shaped): C. matannensis Sarasin & Sarasin, 1898 from Lake Matano and Lake Mahalona, C. loehensis Kruimel, 1913 from Lake Masapi (all on Sulawesi) and C. moltkiana Prime, 1878 from Lakes Maninjau and Singkarak (on Sumatra). Details of the anatomical and histological features of ctenidia are described for each type of brooding, and some trends in the evolution of reproductive strategies within the Corbiculidae are discussed, comparing them with those known from other limnic molluscs.     

Locomotion is not a privilege after birth: Ultrasound images of viviparous shark embryos swimming from one uterus to the other

Underwater ultrasound, a new tool for observing the internal body parts of aquatic animals by scuba divers, allowed us long‐term and frequent observations of the embryos of captive aquatic vertebrates. New ultrasound data of captive tawny nurse sharks (Nebrius ferrugineus) revealed that their embryos frequently migrate between the right and left uteri during gestation. This report is the first reliable evidence of active embryonic locomotion in live‐bearing vertebrates and is contradictory to the concept of “sedentary embryo” which has mainly arisen from studies of mammals. The tawny nurse shark is unique among orectolobiform sharks, in which the embryo develops by feeding on sibling eggs in utero. Thus, we hypothesized that swimming aids in an efficient search and capture of these eggs in the uterine environment.     

Pathogenicity and infection cycle of Vibrio owensii in larviculture of the ornate spiny lobster (Panulirus ornatus)

The type strain of Vibrio owensii (DY05) was isolated during an epizootic of aquaculture-reared larvae (phyllosomas) of the ornate spiny lobster (Panulirus ornatus). V. owensii DY05 was formally demonstrated to be the etiological agent of a disease causing rapid and reproducible larval mortality with pathologies similar to those seen during disease epizootics. Vectored challenge via the aquaculture live feed organism Artemia (brine shrimp) caused consistent cumulative mortality rates of 84 to 89% after 72 h, in contrast to variable mortality rates seen after immersion challenge. Histopathological examination of vector-challenged phyllosomas revealed bacterial proliferation in the midgut gland (hepatopancreas) concomitant with epithelial cell necrosis. A fluorescent-protein-labeled V. owensii DY05 transconjugant showed dispersal of single cells in the foregut and hepatopancreas 6 h postexposure, leading to colonization of the entire hepatopancreas within 18 h and eventually systemic infection. V. owensii DY05 is a marine enteropathogen highly virulent to P. ornatus phyllosoma that uses vector-mediated transmission and release from host association to a planktonic existence to perpetuate transfer. This understanding of the infection process will improve targeted biocontrol strategies and enhance the prospects of commercially viable larviculture for this valuable spiny lobster species.     

Interembryonic regions of the uterus of the viviparous lizard Mabuya brachypoda (Squamata: Scincidae)

Analysis of the structure and physiology of the uterine incubation chambers of viviparous squamates has provided insight concerning adaptations for gestation. However, the literature addressing the biology of the interembryonic regions of the uterus is very limited, presumably because it has been assumed that this area has little role in the development and support of embryos in viviparous squamates. This study was undertaken to examine the histology of the interembryonic regions of Mabuya brachypoda, a viviparous lizard with microlecithal ova and consequently substantial matrotrophic activity. The incubation chambers are oval, distended zones of the uterus, adjacent to the interembryonic regions. The wall of the interembryonic regions includes: mucosa, formed by a cuboidal or columnar epithelium with ciliated and nonciliated cells, and a lamina propria of vascularized connective tissue containing abundant acinar glands; myometrial smooth muscle consisting of inner circular and outer longitudinal layers; and serosa. The segment of the interembryonic region adjacent to the incubation chamber forms a transitional segment that displays folds of the mucosa that protrude into the uterine lumen. The limit of the incubation chamber is well defined by the long mucosal folds of the transitional segment. Long and thin extensions of extraembryonic membranes are present in the lumen of the transitional segment, outside of the incubation chamber region. The presence of abundant uterine glands and extraembryonic membranes in the interembryonic regions during gestation suggests uterine secretory activity and histotrophic transfer of nutrients to embryos in these regions.     

Brooding sea anemones (Cnidaria: Anthozoa: Actiniaria): paragons of diversity in mode,morphology, and maternity

Brooding has been reported in at least 57 species of sea anemone. More than three quarters (44/57) of the species that are known to brood have been described since the last comprehensive treatment of brooding in this lineage. Different authors focusing on different taxonomic groups within sea anemones over the last 115 years have collectively produced an imprecise and inconsistent set of terminology with respect to brooding in general and to the variety of conditions of brooding in particular. In this review, I characterize brooding as a behavior in which offspring are retained by the adult to at least the juvenile stage, in contrast with the more common release of eggs, embryos, or larvae. Brooding occurs in two primary modes, internal and external, in which offspring may be produced via sexual or asexual means. I categorize structures associated with external brooding in three types: pits, chambers, and grooves. Early inferences that external brooding has a primarily bipolar distribution continue to be supported with current data, but it is doubtful that small size and simultaneous hermaphroditism are correlated with brooding in sea anemones. Finally, I identify open questions about brooding in sea anemones and suggest future lines of research that will broaden our understanding of this phenomenon.     

The Systematics and Reproductive Biology of the Galeus arae Subspecific Complex (Chondrichthyes: Scyliorhinidae)

Galeus arae is currently classified as a complex of three subspecies (Galeus arae arae, Galeus arae antillensis, and Galeus arae cadenati). Morphometric and meristic analyses, size at maturity, and variation in color patterns, support the recognition of these taxa as distinct species. All species have well-developed nidamental glands and are oviparous. Galeus arae comprises two geographically disjunct populations that are not distinguishable by the characters we examined. A northern population occurs along the east and Gulf coasts of North America from South Carolina to the Mississippi delta, and the northern coast of Cuba to the north-eastern tip of the Yucatan. A southern population occurs along the Caribbean coasts of Honduras, Nicaragua, and Costa Rica, and some neighboring islands. Galeus antillensis occurs on the northern coasts of Hispaniola and Puerto Rico, and off many of the Leeward Islands. Galeus cadenati occurs off the Caribbean coasts of Panama and Colombia. Distributional data suggest that the three species are distributed allopatrically.     

Viviparous lizard, Eulamprus tympanum, shows changes in the uterine surface epithelium during early pregnancy that are similar to the plasma membrane transformation of mammals

The "plasma membrane transformation" describes a series of ultrastructural, biochemical, and morphological changes that occur in the uterus of many mammals at the time of blastocyst attachment. These changes, regardless of placental type or length of gestation, include alterations to microvillar length and density and the presence or absence of pinopods or uterodomes. Scanning electron microscopy (SEM) was used to 1) document the topographical ultrastructure of the uterus of Eulamprus tympanum, an eastern Australian viviparous skink with a simple chorioallantoic placenta, for the first time; and 2) determine whether changes identified as "plasma membrane transformation" in mammals occur in E. tympanum. Tissues collected over three seasons from nonreproductive subadult females, preovulatory, postovulatory, and early to mid-gestational females were examined. At low magnification the uterine epithelium of subadults displays a distinctive pattern of tissue folding that includes rectangular areas of tissue delineated by deep lateral and transverse folds. At higher magnification, the uterine epithelium surface is composed of two dominant cell types, i.e., those covered by microvilli and ciliated cells. The folding pattern observed in subadults is less evident in vitellogenic females and the cell surfaces appear highly secretory, with bulging cell apices. Tissue from postovulatory lizards has no distinctive folding pattern and cell surfaces are frequently smooth and lack microvilli. Uterine egg chambers lack ciliated cells at the embryonic pole, but display abundant secretory droplets. Thus, the uterus of E. tympanum undergoes a plasma membrane transformation. The scope of this transformation is not fully understood but may be related to the complexity of placental structure and the development of the embryo/fetus at parturition.     

Reproductive biology of the swell shark Cephaloscyllium ventriosum (Carcharhiniformes: Scyliorhinidae)

The Cephaloscyllium ventriosum shark is present in the artisanal fisheries of elasmobranchs on the western coast of Baja California Sur, Mexico. The main characteristics of the sexual maturation of this species based on individuals captured from off north-west Mexico in 2013–2016 are described. The size at maturity of this species was determined for the first time (total length 82 cm for females and 76 cm for males). Most females had one egg case per one uterus, and two per one uterus was an isolated event of low incidence. From the histological analysis of females, it was possible to show sperm storage in the oviducal gland. Fully developed sperm in immature organisms were identified in the testes. The main indicator of the maturity stage of males and their mating activity is the clasper. The present study provides evidence for a reliable estimation of the sexual maturity of these organisms, demonstrating the need for the combination of macroscopic and microscopic methods.