Juveniles of two sillaginids,Sillago aeolus andS. sihama,occurring in a surf zone in the Philippines

Sillaginid juveniles collected from the surf zone at Tigbauan, Iloilo, Philippines, between May 1986 and September 1987 were identified asSillago aeolus (n=702, 8.9–26.0 mm SL) andS. sihama (n=3414, 8.6–22.9 mm SL), based on the numbers of dorsal and anal soft fin rays and vertebrae. The two species were easily distinguishable by the pattern of melanophores distributed on the caudal fin base,S. aeolus having a triangular-shaped cluster, whereas the melanophores formed a vertical line inS. sihama. The ratios of pre-anal and caudal peduncle lengths to SL also differed between the species, both being higher inS. aeolus. The occurrence ofS. aeolus was limited to the dry season, from January to March. On the other hand,S. sihama occurred year-round, although a peak was observed in the dry season, from November to April.     

A new sand whiting, Sillago (Sillago) caudicula, from Oman, the Indian Ocean (Perciformes: Sillaginidae)

A new species of sand whiting, Sillago (Sillago) caudicula, is described based on four specimens collected from Oman, the Indian Ocean. It is easily distinguishable from its four known members of the subgenus Sillago by having a smaller head (29.0–30.1% in standard length), 23–24 soft anal fin rays, 35–36 total vertebrae, body depth at the origin of the second dorsal fin slightly deeper than that at the origin of the first dorsal fin, first and second hypurals fused (in adult) or narrowly separated (in young), third and fourth hypurals fused, and 11 dusky midlateral spots on the body.     

Habitat partitioning by whiting species (Sillaginidae) in coastal waters

Synopsis The ways in which the distributions of six species of whiting (Sillaginidae) in the coastal marine waters of south-western Australia are related to the type of substrate (bare sand vs. seagrass), degree of exposure of habitat, water depth and body size have been investigated. Whiting in near shore waters (< 1.5 m) were sampled using a fine-meshed seine net, while those in shallow (5–15 m) and deep (20–35 m) waters of the inner continental shelf were sampled with a trawl net. Shallow nearshore waters are shown to provide nursery habitats for five of the six whiting species. In these waters, Sillaginodes punctata, Sillago burrus, Sillago schomburgkii and Sillago vittata mainly occur in protected areas, while Sillago bassensis predominantly occupies areas that are more exposed to wave and swell activity. The first three of these species also use estuaries as nursery areas. In nearshore waters, whiting were captured almost exclusively over bare sand, rather than in interpersed beds of the seagrass Posidonia spp., presumably reflecting the fact that the dense canopies produced by the wide blades of Posidonia spp. must inhibit penetration by the benthic whiting species. As 0 + S. punctata increase in size, they tend to move offshore during the day and inshore at night. Many mature representatives of S. schomburgkii are present in nearshore areas, whereas the other four species move offshore into inner-shelf waters as they increase in length. Sillago burrus and S. vittata remain in shallow inner-shelf waters, whereas the larger S. bassensis subsequently migrate into deeper inner-shelf waters. Large Sillago bassensis thus co-occurs with Sillago robusta, which is mainly found in those deeper waters, but does not reach as large a size. The larger S. punctata occupy areas near reefs which could not be sampled by trawl netting. There are thus interspecific differences in (i) the times of recruitment of the 0 + age class into nearshore areas, (ii) the types of habitat occupied during juvenile and adult life, and (iii) the degree to which fish move into more offshore waters as they increase in length, and one species is restricted to deeper waters. The resultant partial segregation among habitats of the coastal waters of south-western Australia by different size groups of these relatively abundant whiting species presumably reduces the potential for intra- and interspecific competition amongst these species.     

Nesting,eggs and larvae of triggerfishes (Balistidae)

Synopsis Triggerfishes construct nests by excavating depressions in sand. Eggs are laid in an adhesive mass and anchored with rubble. A photograph of a newly-hatched embryo is included.     

Characterization of cathepsin B proteinase (AcCP-2) in eggs and larvae stages of hookworm Ancylostoma caninum

Cathepsin B proteinase constitutes a large multigenes family in parasitic and non-parasitic nematodes. The localization of cathepsin B proteinases (AcCP-1 and AcCP-2) in adult worm of Ancylostoma caninum has been characterized (Harrop et al., 1995), but the localization and function in eggs and larval stages remained undiscovered. Here we described the expressing of cathepsin B proteinase (AcCP-2) in Escherichia coli, and immuno-localization of cathepsin B proteinase in eggs and larvae stages of A. caninum. A cDNA fragment encoding a cathepsin B proteinase (AcCP-2) was cloned from A. caninum and expressed in E. coli. Gelatin digestion showed that recombinant cathepsin B proteinase (AcCP-2) has protease activity. The protein level of cathepsin B proteinase in larval and adult worm was detected by western blot. The immuno-localization of cathepsin B proteinase in eggs and larval stages was characterized. The expression of cathepsin B proteinase was more abundant in eggs and larvae stages of A. caninum. It implied that cathepsin B proteinase might play roles in the early development of A. caninum.     

Comparisons between the biology of two co-occurring species of whiting (Sillaginidae) in a large marine embayment

Synopsis We compare the biology of the tropical species Sillago analis and the temperate species Sillago schomburgkii in Shark Bay, a large subtropical marine embayment on the west coast of Australia. This environment constitutes approximately the southernmost and northernmost limits of the distributions of these two species, respectively. The annuli visible in sectioned otoliths of S. analis and S. schomburgkii form annually. Their numbers were thus used to age the individuals of these two species, which are morphologically very similar and live in the same habitats. Although the growth rates of S. analis and S. schomburgkii are very similar until maturity is attained, they subsequently diverge, with S. schomburgkii investing relatively more energy into somatic growth. The maximum total lengths and ages of both the females (320 mm, 6 years) and males (283 mm, 8 years) of S. analis were not as great as those of the females (383 mm, 9 years) and males (302 mm, 9 years) of S. schomburgkii. In Shark Bay, S. schomburgkii spawns earlier and longer than S. analis, i.e. August–December vs. January–March, which would result in the juveniles of these two species recruiting into nursery areas at different times. In addition, S. schomburgkii spawns earlier and for longer in Shark Bay than in temperate marine waters 800 km further south, presumably reflecting the fact that, in that subtropical embayment, water temperatures over which this species typically spawns are attained earlier and last for longer. However, although environmental conditions in Shark Bay and those temperate marine waters differ markedly, the growth of the corresponding sexes of S. schomburgkii in these two water bodies is similar.     

Embryonic, larval and juvenile development of the roughskin sculpin,Trachidermus fasciatus (Scorpaeniformes: Cottidae)

Embryonic, larval and juvenile development of the catadromous roughskin sculpin,Trachidermus fasciatus, were described using eggs spawned in an aquarium. The eggs, measuring 1.98–2.21 mm in diameter, were light reddish-yellow and had many oil globules, 0.05–0.18 mm in diameter. Hatching occurred 30 days after spawning at 2.3–11.3°C. The newly-hatched larvae, measuring 6.9–7.3 mm BL, had a single oil globule, 9–10+25–26=34–36 myomeres and 6 or 7 large stellate melanophores dorsally along the gut. The yolk was almost resorbed, number of pectoral-fin rays attained 16–17, and two parietal, one nuchal and four preopercular spines were formed, 5 days after hatching, at 8.2–8.4 mm BL. The oil globule disappeared, and one supracleithral spine was formed, 11 days after hatching, at 8.9–9.5 mm BL. Notochord flexion began 15 days after hatching, at 9.7–10.3 mm BL. A posttemporal spine was formed 20 days after hatching, at 10.7–10.9 mm BL. The first dorsal fin spines (VII–VIII), second dorsal fin and anal fin rays (18–19, 16–18, respectively) appeared 23 days after hatching, at 12.0–13.7 mm BL. The pelvic fin spine and rays (I, 4) were formed and black bands on the head and sides of the body began to develop 27 days after hatching, at 13.8–15.8 mm BL. Newly-hatched larvae swam just below the surface in the aquaria. Preflexion larvae (8.9–9.5 mm BL), in which the oil globule had disappeared, swam in the middle layer, while juveniles (13.8–15.8 mm BL) began swimming on the bottom of the aquaria. Swimming behavior observed in the aquaria suggested that the fish started to change to a demersal existence at the juvenile stage.     

Sensorimotor transformation from light reception to phototactic behavior inDrosophila larvae (Diptera: Drosophilidae)

In this paper we examine theDrosophila melanogaster larval response to light. We survey the morphology of the larval visual and motor systems in relation to larval locomotory behavior and phototaxis. In addition, this paper proposes a model of sensorimotor transformation and examines the reversal in taxis occurring at theD. melanogaster larval wnadering stage.     

Growth and morphological development of larval and juvenileepinephelus bruneus (perciformes: Serranidae)

The growth and morphological development of larval and juvenileEpinephelus bruneus were examined in a hatchery-reared series. Average body length (BL) of newly-hatched larvae was 1.99 mm, the larvae growing to an average of 3.96 mm by day 10, 6.97 mm by day 20, 12.8 mm by day 30, 22.1 mm by day 40 and 24.7 mm by day 45 after hatching. Newly-hatched larvae had many mucous cells in the entire body epidermis. By about 4 mm BL, the larvae had developed pigment patterns peculiar to epinepheline fishes, including melanophores on the dorsal part of the gut, on the tips of the second dorsal and pelvic fin spines, and in a cluster on the ventral surface of the tail. Spinelets on the second dorsal and pelvic fin spines, the preopercular angle spine and the supraocular spine, had started to develop by about 6 mm BL. The notochord tip was in the process of flexion in larvae of 6–8 mm BL, by which time major spines, pigments and jaw teeth had started to appear. Fin ray counts had attained the adult complement at 10 mm BL. After larvae reached 17 mm BL, elements of juvenile coloration in the form of more or less densely-pigmented patches started to appear on the body. Squamation started at 20 mm BL. Major head spines had disappeared or became relatively smaller and lost their serrations by 20–25 mm BL.     

Lagenidium infection in eggs and larvae of mangrove crab (Scylla serrata) produced in Indonesia

A fungal infection occurred in the eggs and larvae of mangrove crab (Scylla serrata) in seed production in Bali, Indonesia. The causative fungus was classified as a member of the genusLagenidium (Oomycetes, Lagenidiales). After comparison of its biological and physiological characteristics with those ofL. callinectes ATCC 24973, a known parasite of various crustaceans, was concluded that the isolate is a new species ofLagenidium, L. thermophilum, because of its rapid and thermotolerant growth and unique discharge process. Fungal growth was observed on PYG agar containing 0–5.0% (w/v) NaCl and 0–2.5% (w/v) KCI. Similar pathogenicity toward the zoeae of swimming crab (Portunus trituberculatus) was demonstrated.     

Suitability of exotic and native lady beetle eggs (Coleoptera: Coccinellidae) for development of lady beetle larvae

Predation upon lady beetle (Coleoptera: Coccinellidae) eggs in the field is most often instances of egg cannibalism by larvae or adults while the majority of the remaining predation events upon coccinellid eggs is done by other species of Coccinellidae. Thus the recent introduction and establishment of Harmonia axyridis in the US could negatively affect native species of Coccinellidae via egg predation. However, little is known regarding the suitability of interspecific coccinellid eggs as a food source for larval development. In this study, it was found that native first or third instar Coleomegilla maculata and Olla v-nigrum larvae were incapable of surviving to the adult stage when provided solely exotic H. axyridis eggs. In stark contrast, H. axyridis larvae survived equally well when cannibalizing eggs or eating eggs of either native species. When C. maculata and O. v-nigrum were grouped as ‘native’ and compared with the exotic H. axyridis, more native eggs were attacked than exotic eggs and a higher percentage of eggs was attacked by H. axyridis larvae. Native and exotic larvae attacked a similar percentage of native eggs but native larvae attacked significantly fewer exotic eggs than did exotic larvae. These data suggest that H. axyridis may prey upon the eggs of these native species, when encountered in the field, compared with the likelihood of the native species preying upon H. axyridis eggs. Therefore, eggs of the native species C. maculata and O. v-nigrum will continue to be subjected to cannibalism and also to possible predation by other native species and the exotic H. axyridis.     

A cysteine endopeptidase from tick (Rhipicephalus (Boophilus) microplus) larvae with vitellin digestion activity

The hard tick Rhipicephalus (Boophilus) microplus is a blood-sucking ectoparasite. R. microplus free-living stage comprises egg development, hatching, and subsequent larval development until encountering a host. In order to complete the embryological development, this tick relies on yolk reserve substances, mainly vitellin (Vt), which is still present in the larval stage. The present study demonstrates presence and digestion of Vt in unfed R. microplus larvae. An increasing proteolytic activity is observed in larval development, as well as a decrease in total protein and in Vt content. Partial purification and characterization of a R. microplus larval cysteine endopeptidase (RmLCE) with Vt-degrading activity is also described. RmLCE has optimal activity at 37 °C at pH 5.0, being unstable at pH ≥ 7.5. This enzyme is active upon fluorogenic peptide substrates and is able to degrade Vt, its putative natural substrate. These results indicate that RmLCE has a role in supporting the nutritional needs of unfed R. microplus larva through Vt proteolysis, allowing survival until the first blood meal.     

A case of abnormal size in eggs and larvae of the Taiga tick,Ixodes persulcatus (Acari: Ixodidae)

Egg batches laid by females of Ixodes persulcatus (maintained under a photoperiod of L:D 20:4 before feeding) contained eggs of two sizes: numerous normal eggs of 0.578 × 0.421 mm and some giant eggs of 0.776×0.515 mm. Giant eggs were 32–34% greater in length and 22–24% greater in width than normal eggs. Females maintained under a short-day photoperiod (L:D 12:12) laid only normal eggs (0.588×0.417 mm). There were no differences between these eggs in viability and developmental time, but larvae hatched from giant eggs were larger (length of body 23–28% greater and of gnathosoma 12–15% greater) than larvae from normal eggs. This dimorphism of eggs and larvae was not sex determined, but may be a maternal photoperiodic effect.     

Studies on the behaviour and substratum preference in juveniles of the marine prawn,Metapenaeus monoceros (Fabricius)

Circadian rhythmicity in the behaviour of the marine prawn, Metapenaeus monoceros (Fab) and its substratum preference has been observed under laboratory conditions. In the morning at 9. a.m. 80% prawns remain buried and in the afternoon at 3 p.m. 60% burrowing was observed. A contrasting situation was observed in the night i.e. 17% burrowing at 9 p.m. and 30% burrowing at 3 a.m. was registered. In the second set of experiments juveniles were subjected to four types of substrata viz. mud, black fine sand, white coarse sand and stones. It was noted that M. monoceros showed more affinity towards the mud and less preference to other substrata. The obtained results are discussed to provide clues for prawn fishing.This work was supported by I.C.A.R., New Delhi through a project on Reprod. Endocr. Edible prawns.     

Spatial and temporal distribution of whiting (Sillaginidae) in Moreton Bay, Queensland

Five species of whiting (Sillaginidae) inhabit Moreton Bay. The school whiting, Sillago bassensis , and stout whiting, S. robusta , are rare, caught occasionally by trawlers in areas of sandy substrates. The sand whiting, S. ciliata , golden-lined whiting, S. analis , and trumpeter whiting, S. maculata , are very common throughout the year. Sillago maculata is distributed almost throughout Moreton Bay, from 1 to 30 m depth. Sillago ciliata and S. analis are shallow water dwellers, from the shoreline to 3 m and 5 m depth, respectively. In the shallow waters, S. ciliata prefers the sandy substrates and S. analis the mud-sandy substrates. Distributions related to the depth, habitat preference, juvenile-adult grounds, food availability, interspecific competition, and winter season are discussed.     

Ontogeny of prey attack behaviour in larvae and juveniles of three European cyprinids

Synopsis The ontogenetic change in time costs of prey attacks as well as the change in capture efficiency for representative cladoceran and cyclopoid prey was investigated in roach, Rutilus rutilus, bleak, Alburnus alburnus, and blue bream, Abramis ballerus. Video recordings were used for measuring the timing of attacks, whereas capture efficiencies were determined by direct observation. Decreases in the time cost of attacks reflect the decreasing importance of prey fixation during growth of the fish. No differences in capture efficiencies were found among the three cyprinid species, indicating that attack behaviour is unlikely to function as a basic mechanism leading to differences in prey selectivity among the investigated species. Increasing capture efficiency during early development may lead to increasing selectivity for cyclopoid prey in the field.     

Growth,maturation and survival in a laboratory-reared Rhabdocoelid Turbellarian,Macrostomum orthostylum (BRAUN 1885)

Growth, maturation and survival of a free living turbellarian Macrostomum orthostylum (BRAUN), from a brackish water fish-farm, were studied in the laboratory under a constant temperature of 24 °C. The worms tolerated a wide range of salinity (1 to 30‰). Maximum growth (total length) of 1000 μm was attained in 56 days with a mean growth rate of 15.7 μm d^-1. Minimum maturation time (7 days) and highest longevity (112 days) were recorded in 9%. salinity. Survival period was considerably longer at lower salinities (1 to 10‰) and showed negative relationship with higher salinities (11 to 30‰).