The distribution and orientation of epizoic barnacles on crabs

The distribution and orientation of Balanus crenatus on Carcinus maenas is described. Elminius modestus was also found on C. maenas but it was not common. Both species of barnacle were also found on Cancer pagurus, although neither species of barnacle appeared to be as common on Cancer as on Carcinus. Possible reasons for this are discussed.
Treating the carapaces of similar sized C. maenas as sampling units it is clear that the distribution of B. crenatus over these sampling units is not random but is aggregated. This probably arises because of the gregarious nature of the cyprids when they settle out but other possibilities are considered. B. crenatus on the carapace of C. maenas is found exclusively in the grooves and depressions on the carapace and this is because the cyprids preferentially settle in concavities.
The orientation of B. crenatus also shows a consistent pattern, with the cirral nets facing predominantly backwards. This pattern could arise because the barnacle cyprids orientate to water currents, generated by the exhalant respiratory currents, flowing forwards over the carapace.     

The structure and modification of integumental tissues in Pagurus bernhardus (L.) (Decapoda: Anomura)

The histological structure of cephalothoracic and abdominal integuments has been studied in the hermit crab Pagurus bernhardus (L.). In the branchial region of the carapace, the integument shows a similar structure as described hitherto in a number of other decapod species; there are a thin epicuticle, an exocuticle, and a relatively thick endocuticle, followed by a layer of columnar epithelium and underlying connective tissue. This pattern is repeated on the inner surface of the carapace fold but with generally thinner cuticular layers. Within the connective tissue there are tegumental glands, haemocytes, and some reserve inclusions. The abdominal integument shows a modified cuticle structure which is probably related to its specific function as an adhesive organ attaching the hermit crab to the inner surface of the gastropod shell. The cuticle is uncalcified and it shows deep wrinkles and grooves. Endocuticle and exocuticle are thick and layered whereas the epicuticle is very thin. Large funnel-shaped ducts with secretions occur frequently in the abdominal integument. The cells that are responsible for these secretions are described. The chemical nature of integumental structures has been studied with histochemical tests.     

Phyllocarida and the origin of the Malacostraca

Tentative homologies with Decapoda are proposed for grooves on the carapace of Echinocaris and Montecaris. Together with F.R. Schram's hoploid trend, reinforced by the discovery of a raptorial limb in Sairocaris, this may strengthen a phyllocarid origin for Eumalacostraca. Both these trends, however, may be parallelisms, and phylogenetic analysis is required. Pleopods are here proved to have been present in additional Archaeostraca, which improves their ancestral condition. E. Dahl's view of the phyllocarids as an evolutionary dead end is falsified from fossils, and the phyllocarids are supported as a stem group of the Malacostraca.     

Embryonic development clarifies polyphyly in ostracod crustaceans

The present study describes the embryonic developmental process of the bioluminescent ostracod crustacean Vargula hilgendorfii . Optical microscopy, scanning electron microscopy, DAPI staining and video recording were used for observations. This study is the first detailed report of the embryonic development of a myodocopid ostracod. Contrary to previous studies, cleavage occurred in the yolk sphere and no evident cleavage furrow was found. No nauplius stage was found, and five pairs of appendages developed simultaneously. A bivalved carapace developed from two independent buds of the carapace valves. The buds of the left and right valves are enlarged, and become combined. The combined 'one-piece' carapace was divided by the formation of a hinge, and the usual bivalved carapace was formed. On the 16th day, embryos hatched as juveniles with six pairs of appendages, a pair of immature appendages, a pair of compound eyes, a median eye and a bivalved carapace. An important suggestion for the classification of Ostracoda is derived from the observed development of appendages and carapace, because the subclass Ostracoda is defined mainly by the similarities of appendages and the bivalved carapace. The present observations clearly show that the developmental process of Myodocopa differs from that of Podocopa, and supports polyphyly of the Ostracoda.     

Morphometric relationships of the caridean shrimp Nauticaris marionis Bate, 1888 at the Prince Edward Islands (Southern Ocean)

The relationships between three measurements of body size (carapace length, total body length and eye diameter) and three measurements of mass (wet, dry and ash-free dry weights) of the caridean shrimp Nauticaris marionis are presented. It is argued that a precisely defined carapace length is the most accurate indicator of body size. A conversion formula relating carapace length to total body length is also provided, as are conversion equations relating the different measures of mass. Accepted: 17 May 1999     

Morphological design and fossil record of the podocopid ostracod naupliar eye

The naupliar eye of podocopid ostracods is a useful character for considering evolution in photic environments. Based on external morphologies and histological observations, naupliar eyes are here categorized into six types. The fossil record demonstrates that the major evolutionary changes in podocopid naupliar eyes occured after the Ordovician. Eye types 1 and 2 are not joined to the carapace by the hypodermal cells, and these two types are found in Palaeozoic ostracods. Eye type 3, 4, 5 and 6 are extended on eye stalks, tightly joined to the carapace by the hypodermal cells, and use the carapace as the refractive cuticle lens. Eye type 3 appeared in the Permian, and eye types 4, 5 and 6 appeared in the Early Jurassic. The design of the podocopid naupliar eye diversified in the Early Jurassic.     

A new method for the measurement of Antarctic krill Euphausia superba dana from predator food samples

Summary Regression functions of total length on carapace length and total length on removed carapace length were calculated for Antarctic krill Euphausia superba Dana for those classes of sex and maturity stage which can be discriminated in predator food samples. The use of removed carapace length as a predictor of total length is highly recommended for animals where total length measurement would be inaccurate, providing that the animal may be staged.     

凡纳对虾形态性状对体重的影响效果分析

选择 6月龄凡纳对虾 176只 ,测定了体长、头胸甲长、胸宽、胸高、额剑上刺数、额剑下刺数、尾长和上市体重共 8个性状 ,采用相关分析和通径分析方法 ,剔除了与体长及头胸甲长有共线性的自变量尾长 ,计算了以形态性状为自变量对体重作依变量的相关系数、通径系数、决定系数及相关指数 ,定量地分析了形态性状对体重的影响效果。结果表明 ,凡纳对虾 5个形态性状与体重的相关系数达到极显著水平 (P<0 .0 1) ;通径分析揭示了多元分析中多个自变量与依变量的真实关系 ,体长、头胸甲长、胸宽、额剑下缘刺数目对体重的通经系数达到显著水平 ,它们是直接影响体重的重要指标 ,其中体长对体重的直接影响(0 .4 2 8* * )最大 ,是影响体重的最主要因素 ,其次为头胸甲长 (0 .2 90 * * )和胸宽 (0 .2 4 5 * * ) ,额剑下缘刺数对体重的直接影响(0 .0 70 * )较小 ;胸高与体重的相关程度很大 (0 .792 3) ,但它与额剑上缘刺数对体重的直接影响都非常小 ,主要通过其他性状间接影响活体重 ,是影响体重的次要因素 ,均被剔除 ;决定系数分析结果与通径分析结果有一致的变化趋势 ;所选形态性状与体重的复相关指数为 R2 =0 .92 13,说明影响体重的主要自变量指标已经找到 ;多元回归分析建立了体长 (X1 )、头胸甲长 (X2 )、胸宽(X3)、     

Taxonomy, morphology and speciation of the Semicytherura henryhowei group (Crustacea, Ostracoda)

The genus Semicytherura belongs to the family Cytheruridae, and was distinguished from Cytherura on the basis of carapace features. Species of Semicytherura from Japan and adjacent seas can be divided into two groups. One is represented by Semicytherura miurensis Hanai, 1957, characterized by a thin, oval carapace covered with fine reticulation. The other is represented by Semicytherura henryhowei Hanai & Ikeya, 1977, characterized by a thick sub-rectangular carapace in lateral view. Semicytherura henryhowei, which is distributed from Hokkaido to Okinawa in Japan, has been regarded as having several morphotypes distinguishable on outline and reticulation of carapace. However, as a result of detailed observations on the copulatory organ, carapace outline and distributional pattern of pore systems, remarkable differences are shown to exist between the two most frequently occurring morphotypes. In order to recognize S. henryhowei sensu stricto, the carapace of the holotype was re-examined. Consequently, neither of the two morphotypes are considered to belong to S. henryhowei due to differences of carapace outline and distribution of pore systems. The two morphotypes are here regarded as independent taxa, described as new: S. kazahanan. sp. and S. sasameyukin. sp. The geographical distributions of the two new species overlap, but their micro-habitats differ from each other; the former lives on calcareous algae on rocky shores, the latter lives on silty sand bottom within the inner bay. A third new species, S. slipperi sp. nov., is also described. In view of their present geographical distributions and fossil records, the origin of this group of species would appear to be the Japanese islands or adjacent areas in and after the Miocene. This group then migrated to the Arctic Ocean and East Pacific Ocean during or before the middle Pliocene.     

Thylacocephala (Arthropoda: Crustacea?) from the Cretaceous of Lebanon and implications for thylacocephalan systematics

An intensive study of a collection of arthropods from the Cretaceous of Lebanon, formerly referred to as stomatopod larvae, reveals that these forms belong to the problematical arthropod class Thylacocephala. The species Protozoea hilgendorfi , P. damesi , and Pseuderichthus cretaceus display defining thylacocephalan characters such as a carapace enclosing the entire body bearing a large anterior optic notch; three pairs of large, raptorial appendages; and a posterior battery of small swimming limbs associated with muscle segments. Unique characters of at least the genus Protozoea are the numerous 'pits' covering the entire carapace, elongated anterior rostral and posterior spines, and a dorsal hinge indicative of a truly bivalved carapace. We note several anatomical curiosities that provide some insight into the anatomy, ecology and phylogenetic relationships of these and other thylacocephalan species. Structures on the carapace surface of thylacocephalans may represent sensory organs comparable to the receptors seen on thecostracan crustaceans. The affinities of the three species described are still not entirely clear, but a phylogenetic analysis of the entire group may resolve this.     

Spreading and orientation of epithelial cells on grooved substrata

The spreading and orientation of epithelial (E) cells was studied on titanium-coated grooved substrata by light, transmission (TEM) and scanning electron microscopy (SEM). Vertical-walled grooves and V-shaped grooves, 3-60 microns deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of micro-electronic components, and the grooved substrata were replicated in Epon. Photolithography was used to prepare photoresist-based and silicon dioxide-silicon substrata with grooves of approximately 2 and approximately 0.5 micron deep, respectively. Cell clusters were markedly oriented by all the grooved substrata examined, with the orientation index being highest for substrata with grooves of the smallest repeat spacing. Time-lapse cinemicrography showed that the grooves directed the migration of E cells, but the control was not absolute, as some cells crossed over the ridges and descended into the grooves. The 0.5 micron grooves appeared less effective than the deeper grooves in directing cell locomotion. SEM and TEM of E cells spreading on the grooved substrata demonstrated that cell processes, including lamellae and filopodia, were capable of bending around and closely adapting to groove edges. E cells did not flatten as extensively on a substratum with 22 microns deep V-shaped grooves as on a smooth surface, although some cells were markedly elongated. One mechanism proposed to explain contact guidance of fibroblasts is that linear elements of the locomotory system, such as microfilament bundles, are unable to operate when bent. The observed flexibility of epithelial cell processes and the ability of substrata with shallow grooves to orient E cells indicate that contact guidance of E cells on micromachined substrata cannot be explained by the mechanical stiffness of long linear cytoskeletal elements.     

Development of the turtle carapace: Implications for the evolution of a novel bauplan

The chelonian carapace is composed of the endochondral ribs and vertebrae associated with a specialized dermis. The ribs are found in an aberrant position compared to those of all other tetrapods; they are superficial and dorsal to the limb girdles. This morphological arrangement, which constitutes the unique chelonian Bauplan, is examined from a developmental perspective. Embryos of Chelydra serpentina were studied during stages of carapace development. Tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapace occurs as the result of an epithelial–mesenchymal interaction in the body wall. A carapacial ridge composed of mesenchyme of the dermis and overlying ectoderm is formed dorsal to the ectodermal boundary between somitic and lateral plate mesoderm. It is the anlage of the carapace margin, in which the ribs will eventually terminate. The ectoderm of the carapacial ridge is thickened into a pseudostratified columnar epithelium, which overlies a condensation in the mesenchyme of the dermis. Patterns of cell proliferation and the distribution of N-CAM and fibronectin in the carapacial ridge are consistent with patterns seen in other structures initiated by epithelial–mesenchymal interactions such as feathers and limb buds. Based on an analogy to this developmental mechanism in the development of the limb skeleton, a further analogy with the evolution of the limbs from lateral fin folds is used to form a hypothesis on the evolution of the carapace from elements of the primitive reptilian integument.     

The size, shape and orientation of pore grooves in the egg shells of Rhea sp.

In the egg shells of Rhea sp. there are grooves on the surface and it is into these grooves that one or more pore mouths open.
Five egg shells of Rhea americana and four of Rhea darwinii were studied in detail in respect of the numbers of pore mouths and the number, length and orientation of the grooves. It was found that R. americana had nearly twice as many pore mouths and grooves as had R. darwinii. Their distribution in both species showed more and longer grooves and more pore mouths in the equatorial regions than in the polar regions of the shell. The grooves were also found to be approximately longitudinally orientated in the equatorial regions but this orientation became less marked towards the polar regions. Not surprisingly longer grooves tended to have more pore mouths than did shorter grooves, but, in addition, broader grooves were associated with greater length too.     

The coelotrich: form and function of an unusual sensillum in Lowrya (Ostracoda: Myodocopina: Cypridinidae)

This study reports a previously undescribed and unique sensillum. Some species of Lowrya Parker 1998 (Ostracoda: Cypridinidae) possess sensillae of an unusual type arranged in a single row parallel to, and near, the anterior, ventral and posterior margins of the external surface of each carapace valve. These sensilla are here termed coelotrichs, and are each centred within an almost spherical cavity in the carapace. The cavity forms at the base of a depression, and the depression in turn lies within a sunken channel on the exterior carapace surface. The opening of the coelotrich cavity bears a 'plug', through which only the widened, divided base of a seta passes. The seta is very fine and stiff throughout most of its length, and exhibits no pores. For most of its length the seta is orientated parallel to the carapace surface, shielded within the sunken channel. The coelotrich is probably a velocity detector, acted upon by the viscous drag of the surrounding fluid. Its function is probably to detect vibrations in the substrate, such as acoustic motion in the surrounding liquid, or steady fluid drainage motion.     

Structure and cuticle formation of the reticulated carapace of the ostracode Bicornucythere bisanensis

Electron microscopic examination revealed fine structures of the adult carapace of Bicornucythere bisanensis , which consists mainly of epicutiele, procuticle, membranous layer, epidermal cells and subdermal cells. Piled membrane structure is recognized as an organic framework of the procuticle. Newly formed cuticle examined with specimens at various stages of the molt cycle clarified the process of cuticle formation. Analysis of the complicated process of cuticular ridge formation permits morphogenetic discussion of surface features of the ostracode carapace of many species. Cuticle formation in close relation to cell boundaries clearly indicates that each polygon of the carapace reticulation is formed by one epidermal cell. The cell-polygon correspondence suggests that ostracode reticulation is important for elucidation of the phylogenic and ontogenic development of multicellular organisms at cell level.
□ Ostracoda, carapace structure, biomineralization, cuticle formation.     

Geographic and gender shape differences in the carapace of Liocarcinus depurator (Brachyura: Portunidae) using geometric morphometrics and the influence of a digitizing method

The current work describes the use of geometric morphometrics in the study of the portunid crab Liocarcinus depurator carapace shape variation along the Mediterranean coast of Spain. As a first step, the differences in shape induced by digitizing the carapace with either a digital camera or a flat bed scanner were investigated. Carapace shape information inferred from the camera images proved different from that obtained from the scanner images. This difference was greater than any shape variation because of crab gender or sample location. Carapace shape was analysed using multiple analysis of covariance (with centroid size as a covariate) of the partial warps and uniform components indicating differences between genders and between sample location; however, significant three-way interaction implied that such differences were gender and location specific. Landmarks identifying carapace width, carapace length and posterior carapace width showed greatest variation; hence gender and location differences were further analysed through the interrelationships between these linear measures. Regression analysis of the relationship between posterior carapace width and the ratio of carapace width to carapace length indicated clear differences between locations but not between genders. Crabs from the Alborán Sea had proportionally wider posterior carapaces than those from Alicante or North Catalonia. This finding may represent the difference between a southern influx of an Atlantic population distinguishable from a more northerly Mediterranean one, which would be in agreement with the overall oceanographic surface circulation pattern in the western Mediterranean.     

Push or Pull? The light‐weight architecture of the Daphnia pulex carapace is adapted to withstand tension,not compression

Daphnia (Crustacea, Cladocera) are well known for their ability to form morphological adaptations to defend against predators. In addition to spines and helmets, the carapace itself is a protective structure encapsulating the main body, but not the head. It is formed by a double layer of the integument interconnected by small pillars and hemolymphatic space in between. A second function of the carapace is respiration, which is performed through its proximal integument. The interconnecting pillars were previously described as providing higher mechanical stability against compressive forces. Following this hypothesis, we analyzed the carapace structure of D. pulex using histochemistry in combination with light and electron microscopy. We found the distal integument of the carapace to be significantly thicker than the proximal. The pillars appear fibrous with slim waists and broad, sometimes branched bases where they meet the integument layers. The fibrous structure and the slim‐waisted shape of the pillars indicate a high capacity for withstanding tensile rather than compressive forces. In conclusion they are more ligaments than pillars. Therefore, we measured the hemolymphatic gauge pressure in D. longicephala and indeed found the hemocoel to have a pressure above ambient. Our results offer a new mechanistic explanation of the high rigidity of the daphniid carapace, which is probably the result of a light‐weight construction consisting of two integuments bound together by ligaments and inflated by a hydrostatic hyper‐pressure in the hemocoel. J. Morphol. 277:1320–1328, 2016. © 2016 Wiley Periodicals, Inc.     

Fibroblasts on micromachined substrata orient hierarchically to grooves of different dimensions

Contact guidance was studied by light, scanning (SEM) and transmission electron microscopy (TEM) in cultures of human gingival fibroblasts cultured on grooved surfaces. The grooves were originally produced in silicon wafers by micromachining, a process which is based on the methods used to fabricate microelectronic components, and the grooved surfaces were then replicated in Epon. Micromachining enables precise control of groove depth, groove spacing, and groove shape to be obtained. In silicon wafers with appropriate crystal orientation, a second smaller set of grooves, called the minor grooves, is found on the floor of the major grooves. The minor grooves are oriented at a 54 degree angle to the major grooves, so that cells cultured on such surfaces are concurrently exposed to grooves of different dimensions which direct cell migration in different directions. Marked fibroblast alignment with the major grooves was observed both within the grooves and in the intervening flat ridges between the grooves. In addition, shallow and closely spaced grooves in epon or titanium-coated polymer or silicon were also capable of orienting fibroblasts. Although the minor grooves were able to orient fibroblasts in the absence of any other orienting influence, when fibroblasts were concurrently exposed to major and minor grooves the cells aligned themselves with the major grooves. TEM showed that the cellular filamentous cytoskeletal elements reflected the orientation of the cell as a whole. Fibroblasts on grooved substrata appeared to have more filopodia and to round up more frequently than fibroblasts cultured on flat substrata. It is suggested that both the mechanical properties of the cytoskeleton as well as the durability of the cellular attachment to groove edges may play a role in the contact guidance effected by grooved surfaces produced by micromachining.     

The influence of starvation and copper exposure on the composition of the dorsal carapace and distribution of trace metals in the shore crab Carcinus maenas (L.)

1. The influence of starvation and copper exposure on the composition of the carapace of the shore crab, Carcinus maenas has been investigated. The effects of the concentrations of selected trace metals in the carapace and midgut gland have also been examined.2. Differences in nutritional state did not affect the concentrations or relative proportions of the principle carapace components (calcium, chitin and protein), but starvation was associated with a reduction in carapace copper concentration. Copper concentration in the midgut gland increased in “starved” crabs, while midgut gland zinc and calcium concentrations remained unchanged.3. Starvation in combination with copper exposure (0.5 mg Cu/1) resulted in alterations in both carapace composition and trace metal loads. Carapace calcium concentrations were reduced significantly following copper exposure irrespective of the nutritional state of the crabs. However, the reduction was more marked in “fed” crabs than in “starved” animals.4. Copper-exposed crabs exhibited raised carapace copper concentrations while carapace zinc concentrations were depressed. Such changes were most pronounced in copper-exposed “starved” crabs.5. Calcium concentrations in the midgut glands of “starved” copper-exposed animals were significantly elevated compared with those in either control or “fed”, copper-exposed crabs.6. The findings are discussed with regard to their ecotoxicological significance.     

Nuclear grooves in cytologic preparations. A study of the utility of this feature in the diagnosis of papillary carcinoma

The sensitivity and specificity of nuclear grooves and inclusions for papillary carcinoma was investigated in 32 touch preparations and 69 fine needle aspiration cytologic preparations of the thyroid. Ultrastructurally, these grooves and inclusions are cytoplasmic invaginations into the nucleus. Overall, 100% of the papillary carcinomas contained nuclear grooves while only 70% contained inclusions. Grooves, however, could be seen in 70% of nonpapillary neoplasms and in 56% of nonneoplastic conditions of the thyroid, albeit generally fewer in number and often not as distinct. Inclusions were present in 13% of nonpapillary neoplasms and were absent in nonneoplastic conditions. Some nuclei on cytologic preparations contain lines that are probably artifacts of chromatin alignment and do not represent true nuclear grooves. Since such lines may be indistinguishable from true grooves, grooves should be used cautiously and in conjunction with other criteria in the diagnosis of papillary carcinoma.