Species Of Brachyura Research Articles

Distribution and composition of Decapod larvae assemblages on the Berlengas archipelago and Peniche coast (western coast of Portugal)

For the first time, the decapod larval community in the Berlenga and coastal Peniche region have been investigated in detail, from a short-term time series (2015 – 2020). Sampling was conducted in two locations, at Berlengas archipelago, and near the coast, at Peniche. The communities found at both stations were revealed to be 80% different in terms of species composition, but species of Brachyura, Caridea, and Anomura were the most abundant in both locations. A marked seasonality, with abundance peaks during summer and autumn, was found for the assemblages near the coast, but absent in the assemblages of the Berlenga region. This suggests that factors other than the environmental variables examined in this study may play a crucial role in shaping the assemblages more offshore. Water temperature, upwelling index, salinity, and chlorophyll-a were the main factors dictating species abundance, especially at Peniche. This emphasizes the significant role of the Iberian upwelling productivity, which in turn influences decapod communities. Also, the progressive warming of coastal water will most likely have a negative impact on the decapod meroplanktonic life forms, with further consequences on recruitment and adult life stages.

Range Extension of Two Brachyuran Crabs (Crustacea: Decapoda), Acanthonyx inglei Tirmizi & Kazmi, 1988 (Epialtidae) and Scalopidia indica Ng & Castro, 2013 (Scalopidiidae) in India

Two species of brachyura, Acanthonyx inglei Tirmizi & Kazmi, 1988 (Epialtidae) and Scalopidia indica Ng and Castro (Scalopidiidae) are recorded for first time from the coastal waters of India. Acanthonyx inglei has so far been reported only from Pakistan, while Scalopidia indica has so far been reported from Andaman Sea.

Reproductive biology of the ghost crab, Ocypode rotundata Miers, 1882 (Decapoda, Ocypodidae) at Qeshm Island, Persian Gulf

AbstractThis study aimed to investigate some key aspects of the reproductive strategy ofOcypode rotundataMiers, 1882 from southwest beaches of Qeshm Island, Persian Gulf, Iran, by providing information regarding its sex ratio, sexual maturity, spawning period and fecundity. Samples were taken monthly, from February 2015 to January 2016. Size at the onset of morphometric maturity was estimated at 38.57 mm carapace width. The overall sex ratio (males/females) was observed as 1.13 : 1.00. On monthly based analyses, the sex ratio showed no significant differences, although a significant deviation was observed toward males in the larger size classes. According to the gonadosomatic index (GSI), gonad maturity and occurrence of ovigerous females, the main breeding season occurs from March to October, with a remarkable peak in June. Fecundity ranged from 24 152 to 10 5287 eggs per individual, with a mean value of 52 389 ± 25 660. The ratio between fecundity and carapace width varied from 632 to 2044 eggs/mm (mean: 1198 ± 472 eggs/mm) and fecundity relative to total mass varied from 771 to 1965 eggs/g (mean: 1336.66 ± 425.43 eggs/g). The reproductive output ranged from 1.04 to 3.78 (mean: 2.35 ± 0.90). The shape of the egg was spherical and it included 6 stages of growth, ranging from fully filled with yolk to fully occupied by the embryo. We concluded that reproduction inO. rotundatais seasonal, and that spawning occurs in an appropriate period to ensure maximum survival of the offspring. The fecundity ofO. rotundatais higher than that of other species of Brachyura, with GSI variations being related to temperature. Overall, the results of this study provide relevant information for the reproduction in general and the breeding seasons ofO. rotundata, whicht can be useful for conservation and management policies aimed at preserving the biodiversity of ghost crabs along the Persian Gulf’s sandy shores.

The Brachyura and Anomura fauna (Decapoda; Crustacea) in the Arvoredo Marine Biological Reserve on the southern brazilian coast

Eight species of Brachyura and two species of Anomura were registered for the first time on the Santa Catarina coast, in the waters around the Arvoredo Marine Biological Reserve. The animals were collected by scuba divers, between 3 and 22 meters depth, from September 2001 to February 2003. A total of 31 decapod species were collected, and most of the new occurrences had already been registered in the adjacent northern waters.

Early life history of a seahorse, Hippocampus mohnikei , in Tokyo Bay, Japan

The early morphological development, seasonal and spatial occurrence patterns, and food habits of a seahorse, Hippocampus mohnikei, in offshore waters of Tokyo Bay, central Japan, were studied on the basis of 206 juvenile and young specimens (6.0–65.3 mm TL) collected between August 1995 and January 1999. All the specimens were collected within the period from May to January, inclusive, each year. In the least developed specimen (6.0 mm TL), the number of dorsal, anal, and pectoral fin rays had attained the adult complement, whereas the minute caudal fin, consisting of two rays, was present in juveniles of 6.0–26.4 mm TL. Hippocampus mohnikei≧35 mm TL, being larger than settlement size (ca. 30 mm TL), had very low gut fullness index values (GFI = 0, >70% of specimens), whereas those of 15–29 mm TL had higher values (GFI = 2–4, >80% of specimens). In addition, larger individuals selectively fed on larger planktonic animals (species of Brachyura), which occurred naturally at low densities, although smaller food items, such as Oithona davisae and Penilia avirostris, occurred abundantly, being consumed by smaller H. mohnikei individuals (15–34 mm TL). These results indicated that food availability for H. mohnikei in offshore waters of Tokyo Bay is significant for individuals larger than settlement size, because their food preference would shift from smaller food items to larger food items, which would be scarce in their environments.

Diversity, biomass and production of decapod crustacean larvae in a changing environment

Summary There is a latitudinal gradient in the species richness of Decapoda with pelagic larvae. For example, only two species of Brachyura are found around Svalbard, 54 species are known from the English Channel and ~100 from the Atlantic coast of the Iberian peninsula. The distributions of many species are limited by effects of temperature. Intermoult times of larvae are inversely related to temperature. In the field the size of larvae is inversely related to temperature, the relationship tending to increase in significance in successive larval stages. The timing of the seasonal occurrence of larvae of decapod species in the plankton is also related to temperature, to a greater extent than are seasonal cycles of the holoplankton. These effects of temperature on larval development influence the biomass and production of the larvae in the plankton. Some potential effects of climate change on the distributions and dynamics of planktonic larvae of decapods and consequent changes in their diversity, biomass and production can be predicted insofar as temperature is a limiting factor.

HIGHLY REPETITIVE DNA SEQUENCES UNIQUE TO AEGLIDAE (ANOMURA)

Highly repetitive DNA sequences were investigated in order to shed light on evolutionary relationships in groups of Decapoda. The investigation emphasized the relationships AeglidaeAnomura and between different species of Aegla. Analyses of molecular restriction and hybridization patterns (RP and HP, respectively) were used as experimental approaches. Highly repetitive restriction fragments obtained from species of Brachyura, Anomura, and Aeglidae were isolated and employed as molecular probes. Our results suggest that some highly repetitive DNA sequences are evolutionarily conserved among Caridea, Brachyura, and Anomura. Moreover, a 400-bp band appears to be conserved among Aeglidae, since it was exhibited by all species studied. Relative quantification of the 400-bp band showed that it is highly conserved in these species. The Aeglidae is a monotypic family that is restricted to South American temperate and subtropical fresh waters (Argentina, Uruguay, Chile, Bolivia, Brazil, and Paraguay), a unique phenomenon among anomurans. The only known fossil record is that of the marine species Haummuriaegla glaessneri Feldmann from New Zealand

Occurrence of a shadow response among brachyuran larvae

A closed-circuit television system was used to study phototaxis and behavioral responses upon sudden decreases in light intensity in light-adapted Stage I zoeae from 7 species of Brachyura (Panopeus herbstii, Menippe mercenaria, Uca pugilator, Callinectes sapidus, Sesarma cinereum, Pinnotheres maculatum, and Libinia emarginata). All species except one show positive phototaxis to high intensities of 500 nm light and negative phototaxis to low intensities. Upon a sudden light intensity decrease, larvae show a shadow response, which depends upon the initial and final intensities. If the initial intensity is sufficient to induce positive phototaxis, and the light is extinguished, the larvae of 6 species stop swimming and passively sink (sinking response). Reducing the intensity to an absolute level that causes negative phototaxis, induces a sinking response followed by negative phototaxis. For intensity reductions that occur in the intensity range above that for negative phototaxis, a sinking responseis observed. The intensity decrease that initiates the sinking response is independent of initial stimulus intensity and duration, is consistent between species, and is equivalent to a decrease by 0.5 OD (optical density) units. The sinking response is greatest at intensity decreases of at least 1.0 to 1.1 OD units. It is concluded that the shadow response is common in brachyuran larvae inhabiting coastal-estuarine areas.

Sterols of crustacea

1. 1. Sterol compositions of 14 species of Crustacea were determined by high-resolution gas-liquid chromatography (GLC). 2. 2. Cholesterol was the major sterol in all species and comprised from 99 to 100 per cent of the total sterol in the euphausid, Nyctiphanes norvegica, 4 species of the suborder Macrura, and i species of the Brachyura. Geryon quinquedens. 3. 3. Desmosterol, when it was present, was the second principal sterol. 4. 4. Six other minor sterols were identified in certain species by comparing the retention times on GLC with 37 reference sterols. 5. 5. Thin-layer chromatography and mass spectrometry were used to search for cholestanol in 5 species of Crustacea but none was detected. 6. 6. There was no variation in the sterol compositions of May, July, and October samples of Chionoecetes opilio, suggesting that there is little or no seasonal variation. 7. 7. Species of the suborder Macrura had higher average total lipid, unsaponifiable, and sterol contents than species of the suborder Brachyura. The range of total sterol in the former group was 70–140 mg. per 100 g. wet weight of tissue and m the latter 40–100 mg. per 100 g.

A METHOD FOR DEVELOPING BRACHYURAN EGGS IN VITRO1

The larvae of six species of Brachyura have been successfully hatched by detaching the eggs from the female, placing them in compartmented boxes, and maintaining them on an Eberbach variable speed shaker at constant temperatures at different salinities. In addition to providing thousands of normal larvae of known species for experimental purposes, the method has the following advantages: it provides adequate aeration, prevents the spread of fungi and protozoans throughout the egg mass, and permits the use of a relatively small number of eggs from the same animal in a limited space.

Moulting hormones in Palaemon (=Leander) (Crustacea Decapoda) II. Differences between populations

Eye-stalk removal in certain species of Brachyura and Astacura has almost invariably led to the initiation of proecdysis. In other decapod crustaceans, however, there have been significant variations in the results of this operation. Thus Travis (1951) found that eye-stalk ablation had no effect on the duration of the moult cycle in Panulirus argus. And in the Natantia, even in a single species, quite different results have been reported. Drach (1944) found that eye-stalk removal in Palaemon (=Leander) serratus (Pennant) led, as in crabs, to the initiation of proecdysis and to accelerated moulting. In ignorance of this work I repeated some of the same experiments and found that eye-stalk removal in P. serratus led to slower moulting (Carlisle, 1953 a)— a result quite opposite to that of Drach. Scheer & Scheer (1954) confirm my results in the same species.

LI.—Seven new species of Brachyura from the Coasts of China

LI.—<i>Seven new species of Brachyura from the Coasts of China</i>