Pleuroncodes Planipes Research Articles

Spectral sensitivity and visual pigment of the compound eye of the galatheid crab Pleuroncodes planipes

The compound eye of the galatheid crab Pleuroncodes planipes has been studied by means of visual pigment extractions and spectral sensitivity measurements under various conditions of adaptation. A photosensitive pigment with maximum absorption at 503 nm was identified. Its chromophore is retinal. The spectral sensitivity maximum is near 523 nm in the dark-adapted eye. Selective adaptation experiments suggest that the apical region of the eye has a homogeneous receptor population. The spectral sensitivity characteristics of P. planipes seem to be an adaptation to its mainly benthic life.

The carotenoid pigmentation of Pleuroncodes planipes stimpson (Crustacea: Decapoda: Galatheidae

1. 1. The carotenoid pigments found in Pleuroncodes planipes were β-carotene, two esters of astaxanthin. 2. 2. Pigment yields were estimated to be from 8·3 to 9·9 mg/100 g of whole animal. 3. 3. P. planipes appears to be a good source of carotenoids for fishes which can utilize dietary astaxanthin.

The lipids of krill (Euphausia species) and red crab (Pleuroncodes planipes).

The composition of the lipids of two samples of krill and one of "red crab" was determined by thin layer, column and gas chromatographic procedures. A large number of unusual fatty acids were present.

Proximate and lipid analyses of krill (Euphausia species) and red crab (Pleuroncodes planipes)

Proximate and lipid analyses of krill (Euphausia species) and red crab (Pleuroncodes planipes)

DISTRIBUTION OF THE LARVAE OF PLEURONCODES PLANIPES IN THE CALIFORNIA CURRENT

Zoeae and megalopas of Pleuroncodes planipes Stimpson were found in 483 of 2,546 plankton samples from the California Current in 1957 and 1959. Their distribution in the samples showed that 1) breeding occurred during winter, mostly in February and March; 2) while some breeding could be ascribed to offshore pelagic adults, the greatest larval concentrations were over the continental shelf, often only in the presumed presence of benthic adult populations; 3) breeding extended far to the north of the usual range in the warm years centered around 1959, though it was probably not successful in the extreme north; and 4) there was clear evidence of late zoeae and megalopas being carried offshore in accordance with known geostrophic flow patterns so that at least a high proportion of megalopas had the possibility of changing to the benthic phase only after an excursion into oceanic regions. The data cannot be used to decide whether 5) any of these megalopas do, in fact, achieve a return to the coast or whether 6) any megalopas descend directly into the benthic phase after metamorphosis over the continental shelf.

On the calculation of vertical motion in eastern boundary currents from determinations of horizontal motion : Arthur Robert S., 1965. J. Geophys. Res., 70 (12): 2799–2803

Stomach contents of albacore (Thunnus alalunga) and skipjack (Katsuwonus pelamis) caught off California in August 1983 showed they were feeding on juvenile northern anchovy (Engraulis mordax), other fishes, and planktonic crustaceans. The distribution and diet of these predators were related to mesoscale frontal features visible in satellite sea surface temperature and phytoplankton pigment imagery. Albacore were caught in the vicinity of a filament of cold, pigment-rich surface water that varied with the intensity of coastal upwelling on time scales of several days. Stomachs of albacore caught closer to the filament contained relatively more juvenile anchovy and fewer pelagic red crabs (Pleuroncodes planipes). Skipjack were caught in warm water in the Southern California Bight, north of their normal range due to El Nin˜o warming. They appeared to be feeding most successfully near the strong frontal boundary of a productive, cold water mass south of Pt. Conception, where dense patches of euphausiids were available. Both species were feeding near variable, mesoscale centers of high productivity where prey abundance may be enhanced.

VARIATIONS IN THE LARVAL STAGES OF A DECAPOD CRUSTACEAN, PLEURONCODES PLANIPES STIMPSON (GALATHEIDAE)

1. The young of Pleuroncodes planipes pass through a series of five morphologically discrete zoeal larval stages after hatching, and, except in Stage IV, the larvae change from one stage to the next by a single molt. Larvae in Stage IV may molt from four to eight times without greatly altering their basic morphology. There is evidence from laboratory culturing that the number of these sub-stages may be influenced by the temperature at which the larvae develop, with higher temperatures causing more sub-stages.2. The duration of the larval phase is influenced by the temperature at which the larvae are reared, and the rate of development follows a Q10 of about 1.9. The larval duration is also influenced by rearing conditions other than temperature, for the size of the larval rearing container or the presence of other larvae in the container has also been shown to influence the duration of the larval phase.3. A larval stage was seen in the laboratory which has not been found in nature, and it is probable that the stage was an artifact of laboratory culturing conditions.4. It may be generalized that variation in the number of larval molts is widespread in the Anomura; variation does not commonly occur in brachyuran Crustacea.

THE LARVAL STAGES OF PLEURONCODES PLANIPES STIMPSON (CRUSTACEA, DECAPODA, GALATHEIDAE)

The larval stages of a galatheid decapod crustacean, Pleuroncodes planipes, have been identified, described and figured. There are five stages. First stage larvae were hatched from eggs carried by adults; no larvae molted under laboratory conditions. Larval morphology indicates that the genus Pleuroncodes is more closely allied to the genus Munida than to Galathea. The larvae occur in high densities (42,000/1000 m.3) in the region of Magdalena Bay, Baja California, Mexico.