Squid embryos develop in the perivitelline fluid inside the chorion, which is an envelope secreted by the ovarian follicle. The onset of hatching initiates local dissolution of the chorion when the hatching gland enzyme facilitates the release of the developed paralarvae. In the present study, we investigated the pre-hatching behavioral patterns of Todarodes pacificus embryos and their responses to light after hatching. Observations of orientation were conducted using embryos developing inside chorions embedded within intact egg masses, while phototactic experiments were conducted on paralarvae that hatched from these egg masses. Within the restricted chorion and along the animal–vegetal axis, the embryos demonstrated a variety of orientation patterns that were categorized as swirls, glides, and somersaults. The contributions of these orientations to enhance oxygen diffusion and stimulate paralarval swimming immediately after hatching are discussed. Paralarvae exhibited normal diel vertical migration and responded positively to light sources. Vertical migration and phototaxis in T. pacificus paralarvae could have great adaptive significance because they hatch in neritic environments and are transported by ocean currents during their planktonic life.

Chlamydomonas flagella display surface motility such that small polystyrene beads (microspheres) attached to the flagellar membrane move bidirectionally along the flagellum. This surface motility enables cells to glide on a solid substrate to which they are attached by the flagellar surface. Previous studies suggested that microsphere movement and gliding motility result from the movement of transmembrane glycoprotein(s) within the plane of the plasma membrane, driven by intraflagellar transport (IFT), which utilizes cytoplasmic dynein and kinesin-2. However, it is not well understood how a cell can continuously glide in one direction further than a single flagellar length. Here we show that, during microsphere translocation on the flagella of a non-motile mutant, pf18, some flagellar glycoproteins, including FMG-1B and FAP113, detach from the membrane and attach to the microspheres. We propose that such relocation of surface glycoproteins underlies the ability to glide over a long distance. Surface motility is likely common to cilia/flagella of various organisms, as a similar microsphere movement is observed in the apical ciliary tuft in sea urchin embryos.

In the teleost fish medaka, an adult ovary simultaneously contains developing oocytes at all phases of oogenesis during the breeding season. However, it remains unclear where oocytes at each developmental stage are located in the ovary by the time of ovulation. To examine the relationship between the developmental stage of oocytes and their positions in the ovary of vertebrate medaka during oogenesis, the stage of oocyte development was determined from the diameter of the oocytes and the cellular morphological characteristics, such as the germinal vesicle and micropyle at the animal pole and attaching filaments at the vegetal pole, and the positions of developing oocytes in the ovary in all sections were observed. Furthermore, to investigate the characteristics of the dorsal ovarian epithelium to which the oocytes attach themselves, the dorsal and vegetal ovarian epithelia were observed. The dorsal ovarian epithelium invaginated in spots. When all serial sections of the oocytes were observed, all oocytes at stages I–VIII were attached to the dorsal ovarian epithelium, regardless of whether it invaginated or not.

Abnormal embryos of Chinese giant salamander (Andrias davidianus, CGS) were observed in an imitating ecologic breeding system at 20°C. The aim of the present study was to investigate the relationship of bacterial infection on the early embryonic development of CGS. The ratio of abnormal embryos at 10 days after embryos incubated was 35.0% ± 2.1%, 35.6% ± 2.3% and 34.7% ± 3.4% in six breeding system farms of Hanzhong city in the years 2014, 2015, and 2016, respectively. However, in the standard imitating ecology breeding mesocosm, the proportion of abnormal embryos was about 5%. Six bacteria species in the egg water of the early-dead embryos and eight bacteria species in the gut of healthy CGSs were detected and identified by PCR and 16S rRNA gene sequence homology analysis. All bacteria species in the egg water were also found in the cloaca contents. Cetobacterium somerae and Hafnia alvei, which individually can cause embryo death, were first isolated from egg water and gut of CGSs. Further, the egg jelly membrane and the egg water of embryos did not inhibit bacteria survival and the bacteria could individually lead to CGS larva death. These results suggest that bacteria in the eggs of CGS may derive from the gut and that high-velocity flow of water through nest may decrease bacterial infection of egg in the imitating ecologic culture system.

Tropical and subtropical shallow benthic marine communities are highly diverse and balanced systems that constitute an important natural resource. Knowledge of the genetic diversity, connectivity and reproduction mode of each population is critical to understanding the fate of whole assemblages in times of disturbances. Importantly, the capability of populations to adapt to environmental challenges will be crucial to determining their survival. Here, we report on the population structure of the common reef zoantharian Zoanthus sansibaricus in the northwestern Pacific, by examining populations at three different locations in southern Japan using five highly variable microsatellite markers. Analyses of a population at the species' northern distribution limit combined with analyses of two subtropical populations suggest that habitat characteristics and ocean currents influence the connectivity and genetic diversity of this species. Our findings emphasize the adaptive ability of Z. sansibaricus to different environmental conditions and may help explain the wide distribution and generalist nature of this species.

Few convenient/expeditious methods for identifying the species of shed snake skins in specific areas have been developed. The scales on shed snake skins are permeable to light and can be examined by light microscopy (LM), which is of higher availability—especially for wild animal researchers and citizen scientists—than conventional approach which examines the scale microstructures by scanning electron microscopy. We collected and examined a total of 801 shed samples or scale specimens from 53 snake species in Taiwan and adjacent islands, and developed the first guide to identify the fragmented or faded shed skins of most snake species by LM. Morphological characters of scales can be examined by LM include the apical notch, apical pits, apical lobes, keels, scale symmetry, unpigmented spots (mechanoreceptor-like organs), interscale follicles, cross/longitudinal micro-ridge, oberhautchen cells, rows of spines, light/tiny dots, and other microstructures. The microstructures on the scale specimens prepared by the stripped method and the impression method were similar to those on shed skins when examined by LM. We investigated the variations of scale morphology associated with ontogeny, body region, and position on scales, discussed the character evolution of snake scale morphology, and certified that the interscale follicles and the unpigmented spots could also be useful characters for shed skin identification. The methods and results of this study could be applied to identify squamate skins/sloughs and even fecal remnants.

We observed the morphology of the papilla linguae (filiform, fungiform, foliate, and vallate) and underlying connective tissue cores (CTCs) in Pallas's squirrel (Callosciurus erythraeus thai) using light and scanning electron microscopy. The tongue was caudally elongated and lacked the lingual torus. Filiform papillae were densely distributed along the dorsal surface of the apex, and the rostral and caudal parts of the corpus, but were attenuated in the lingual root. Two or three vallate papillae that were rounded or elongated were situated at the boundary between the caudal part of the corpus and lingual root, and foliate papillae and associated cone-like processes were observable in the lateral margin of the caudal end. The epithelial surface of filiform papillae had a main process and a few associated processes that varied between short and elongated, depending on the location. Filiform papillae CTCs appeared to have a few processes that caudally surrounded a concavity and were morphologically variable based on location. Moreover, fungiform papillae CTCs appeared to be columnar cores and had a shallow convex curve at the top. The Pallas's squirrel's tongue exhibited transitional morphological characteristics between Rodentia and other mammalian species, in that they lacked the lingual torus and had CTCs of lingual papillae that were somewhat morphologically similar to those of other non-Glires species, especially treeshrews and tamarins, rather than those of other Rodentia species.

The ventricle of the fish heart is a chamber that exhibits great morphological and vascular variability among species. However, although the Neotropical region has the greatest taxonomic and functional diversity in freshwater fish, many considerations have been formed without previous knowledge of the ventricular morphology of these fishes. Thus, the purpose of the present study was to describe the anatomy, myoarchitecture, and distribution of coronary vessels in the ventricle of three species belonging to two representative groups from this geographical area, Leporinus elongatus, Hoplias malabaricus (Characiformes) and Pterodoras granulosus (Siluriformes), using gross anatomy and light microscopy. The species L. elongatus and H. malabaricus presented a pyramidal ventricle associated to a mixed myocardium, formed by compact and spongy layers. The mixed myocardium was also observed in P. granulosus, but associated with a sac-like ventricle. The compact layer of the species studied was formed by muscular bundles in longitudinal and circular disposition. The spongy layer constituted most of the ventricular myocardium and was formed by a complex network of trabecular sheets presenting muscle fibers also in longitudinal and circular disposition. Coronary vessels were present in the three species and were observed primarily on the surface of the bulbus arteriosus, later branching on the ventricular surface and penetrating the myocardium only at the compact layer level. These characteristics allow classification of the ventricles studied as type II. Although the type I ventricle is the most common type in teleosts, it is important to emphasize that this type has not been observed in any Neotropical freshwater teleosts studied to date.

In this study, we sequenced the complete mitogenome of Falco amurensis (Falconiformes, Falconidae). The F. amurensis mitogenome is 17,464 bp long, and contains 37 genes, including 13 protein-coding genes (PCGs), two rRNAs, 22 tRNAs, and two non-coding regions (control region and pseudo-control region). Most PCGs initiate with ATG and terminate with TAA. atp8 exhibits the highest evolutionary rate, with cox1 showing the lowest. rrnS and rrnL contain three domains with 46 helices and six domains with 59 helices, respectively. All tRNAs have a typical cloverleaf secondary structure, except that trnS(agy) lacks the dihydrouracil arm. The control region is located between trnT and trnP and the pseudo-control between trnE and trnF. Phylogenetic relationships of 23 species from Falconiformes were analyzed based on the nucleotide sequences of the 13 PCGs and two rRNAs. The results support Falco as a monophyletic taxon, and F. amurensis has a close relationship with the clade containing F. cherrug/F. rusticolus/F. peregrinus.

Feeding specialization is a recurrent issue in the evolution of snakes and is sometimes associated to morphological and/or behavioral adaptations that improve snake performance to exploit a particular food type. Despite its importance for animal fitness, the role of physiological traits has been much less studied than morphological and behavioral traits in the evolution of feeding specialization in snakes. In this context, the energetic cost of post-prandial period is an important physiological factor due to the remarkable effect on the snake energy budget. We collected data on post-prandial metabolic rate (SDA) in five species of pit vipers from the genus Bothrops with different degrees of mammal feeding specialization to test the hypothesis that feeding specialist species have lower energy costs during the digestion of their regular food item when compared to species with a more generalist diet. Our results support this hypothesis and suggest that ontogenetic changes in diet can be accompanied by changes in energy cost of the digestion process.

Splanchnotrophidae Norman and Scott, 1906 is a family of parasitic copepods that infest nudibranchian and sacoglossan sea slugs. In this study, a new species of splanchnotrophid copepod, Lomanoticola nishiharai n. sp., is described based on specimens of both sexes collected from the facelinid nudibranch, Sakuraeolis enosimensis (Baba, 1930), in the Seto Inland Sea off Hiroshima, central Japan. It represents the third species of Lomanoticola Scott and Scott, 1895 and is characterized by the following female characters: the cephalosome distinctly protruded; the second and third lateral processes on the body originated from same bases; the caudal rami bears a seta V which almost same as long as the rami. Ultrastructural observations revealed that the cuticular surface of the lateral process on the female body is covered with numerous protuberances that may have protective functions against the cellular immune system of the host.