scholarly journals Acorn-foraging activity and feeding behaviour by two species of freshwater crabs (Brachyura: Potamidae) from Okinawa Island, Ryukyu Islands, Japan

2014 ◽  
Vol 43 (0) ◽  
pp. 31-40 ◽  
Author(s):  
Takeshi Sasaki ◽  
Tohru Naruse
Keyword(s):  
Feeding Behaviour ◽  
Ryukyu Islands ◽  
Foraging Activity ◽  
Okinawa Island ◽  
Freshwater Crabs

scholarly journals The Migration, Culture, and Lifestyle of the Paleolithic Ryukyu Islanders

2020 ◽  
Author(s):  
Masaki Fujita ◽  
Shinji Yamasaki ◽  
Ryohei Sawaura
Keyword(s):  
Ryukyu Islands ◽  
Small Islands ◽  
Okinawa Island ◽  
Freshwater Crabs ◽  
Behavioral Adaptations ◽  
Human Dispersal ◽  
The Ryukyu Islands ◽  
A Chain ◽  
The Western Pacific ◽  
Human Fossils

Roughly 35,000 years ago, hunting-fishing-gathering people occupied the Ryukyu Islands of Japan, a chain of small-sized islands in the western Pacific. There are Paleolithic sites scattered over most of the relatively large islands, thereby suggesting an extensive human dispersal over the sea at least 30,000 years ago. Recent morphological and genetic studies of the human fossils found in this area revealed that Paleolithic occupants might have an affinity with the modern and prehistoric populations of Southeast Asia. Recent excavation of Paleolithic sediments at Sakitari Cave, Okinawa Island, provided a variety of shell artifacts, including beads, scrapers, and fishhooks, and evidence of seasonal consumption of aquatic animals, especially freshwater crabs. The Paleolithic Ryukyu Islanders’ culture and lifestyle, which made use of unique resources, demonstrate behavioral adaptations to living on relatively small islands.

Supplementary descriptions of Pergalumna amamiensis Aoki, 1984 (Acariformes, Galumnoidea) from Ryukyu Islands

Zootaxa ◽  
2019 ◽  
Vol 4647 (1) ◽  
pp. 378-384
Author(s):  
WATARU HAGINO ◽  
SATOSHI SHIMANO
Keyword(s):  
Body Length ◽  
Morphological Traits ◽  
Granular Structure ◽  
Surface Pattern ◽  
Ryukyu Islands ◽  
Body Width ◽  
Okinawa Island ◽  
Ishigaki Island ◽  
Circular Surface ◽  
Median Pore

A species of oribatid mites, Pergalumna amamiensis was collected from Amami-Ohshima Island, Ishigaki Island, and Okinawa Island, Southwestern Japan. The specimens were studied in detail, and supplementary descriptions are provided; these include features of the rostrum, the subcapitulum and the surface pattern of pteromorphs. The main morphological traits for this species are summarized as follows; body length 519–570 μm, body width 363–410 μm, rostral tip pointed, sensillus with a long stalk covered by minute barbs, porose areas Aa bulbous, porose areas A1, A2, and A3 circular, surface of pteromorphs ornamented by fine granular structure and dense wrinkles, fine granular structure on prodorsum, subcapitulum, genital plates and anal plates, median pore on the notogaster represented as single pore. 

Long-chain n-3 polyunsaturated fatty acids contained in liver and muscle tissues of Okinawan long-spine porcupinefish (Diodon holocanthus Linnaeus 1758)

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yutaka Tashiro
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Polyunsaturated Fatty Acids ◽  
Ryukyu Islands ◽  
Okinawa Island ◽  
Content Type ◽  
Muscle Tissues ◽  
The Ryukyu Islands ◽  
Total Fatty Acids ◽  
Long Chain

Purpose This study aimed to analyze the lipid content and fatty acid composition in the liver and muscle of a porcupinefish species inhabiting waters around the Ryukyu Islands to investigate their potential as a source of long-chain n-3 polyunsaturated fatty acids (LC-PUFAs). Design/methodology/approach Porcupinefish were collected along the Okinawa Island coast. The composition of fatty acids and cholesterol in both liver and muscle were analyzed using a gas chromatograph mass spectrometer. Findings The liver of Okinawan long-spine porcupinefish was rich in lipids whose content correlated to the proportion of liver/body weight. Fatty acid compositions in their liver and muscles were similar to each other. LC-PUFAs occupied 44% of total fatty acids, with docosahexaenoic acid (DHA) being the dominant (42%), whereas eicosapentaenoic acid occupied 2.4%. The liver contained 1,690 mg of cholesterol and 14.8 g of DHA per 100 g, whose proportion decreased in summer compared to other seasons (p = 0.036). Originality/value The liver of Okinawan long-spine porcupinefish, which has not yet been commercially used although its non-toxicity is claimed, can be an excellent source of LC-PUFAs, especially DHA, accentuating its potential in food supplements’ production.

scholarly journals Cuttlefish show flexible and future-dependent foraging cognition

2020 ◽  
Vol 16 (2) ◽  
pp. 20190743 ◽  
Author(s):  
Pauline Billard ◽  
Alexandra K. Schnell ◽  
Nicola S. Clayton ◽  
Christelle Jozet-Alves
Keyword(s):  
Food Availability ◽  
Feeding Behaviour ◽  
Foraging Behaviour ◽  
Foraging Strategy ◽  
The Other ◽  
Foraging Activity ◽  
Experimental Conditions

Some animals optimize their foraging activity by learning and memorizing food availability, in terms of quantity and quality, and adapt their feeding behaviour accordingly. Here, we investigated whether cuttlefish flexibly adapt their foraging behaviour according to the availability of their preferred prey. In Experiment 1, cuttlefish switched from a selective to an opportunistic foraging strategy (or vice versa ) when the availability of their preferred prey at night was predictable versus unpredictable. In Experiment 2, cuttlefish exhibited day-to-day foraging flexibility, in response to experiencing changes in the proximate future (i.e. preferred prey available on alternate nights). In Experiment 1, the number of crabs eaten during the day decreased when shrimp (i.e. preferred food) were predictably available at night, while the consumption of crabs during the day was maintained when shrimp availability was unpredictable. Cuttlefish quickly shifted from one strategy to the other, when experimental conditions were reversed. In Experiment 2, cuttlefish only reduced their consumption of crabs during the daytime when shrimps were predictably available the following night. Their daytime foraging behaviour appeared dependent on shrimps' future availability. Overall, cuttlefish can adopt dynamic and flexible foraging behaviours including selective, opportunistic and future-dependent strategies, in response to changing foraging conditions.

Amamiku, a new genus for the true freshwater crab, Candidiopotamon amamense Minei, 1973 (Decapoda: Brachyura: Potamidae), from the Central Ryukyu Islands, Japan

Zootaxa ◽  
2004 ◽  
Vol 653 (1) ◽  
pp. 1 ◽  
Author(s):  
TOHRU NARUSE ◽  
RYOKO SEGAWA ◽  
SHIGEMITSU SHOKITA
Keyword(s):  
New Genus ◽  
Ryukyu Islands ◽  
Freshwater Crab ◽  
Freshwater Crabs

Amamiku, a new genus, is established for Candidiopotamon amamense Minei, 1973. Amamiku is morphologically most closely related to Candidiopotamon Bott, 1967, but they can be differentiated by their male first pleopods. A key to the genera of the Japanese true freshwater crabs is also provided.

On Two New Species of Geothelphusa Stimpson, 1858 (Decapoda, Brachyura, Potamidae) From the Ryukyu Islands, Japan

Crustaceana ◽  
1998 ◽  
Vol 71 (7) ◽  
pp. 778-784 ◽  
Author(s):  
J.-Y. Shy ◽  
Peter K.L. Ng
Keyword(s):  
New Species ◽  
Type Locality ◽  
Ryukyu Islands ◽  
Freshwater Crabs ◽  
Southern Japan ◽  
The Ryukyu Islands ◽  
Two New Species

AbstractTwo new species of potamid freshwater crabs of the genus Geothelphusa are described from the Ryukyu Islands in southern Japan. Although both G. shokitai sp. nov. and G. minei sp. nov. are allied to G. candidiensis (type locality Taiwan), they differ from that species and from each other in the form of their carapaces, ambulatory leg proportions, and structure of their male first pleopods.

scholarly journals Low-Frequency Earthquakes along the Ryukyu Islands Triggered by Teleseismic Earthquakes

2021 ◽  
Author(s):  
Ayumi Kinjo ◽  
Mamoru Nakamura
Keyword(s):  
Surface Waves ◽  
Low Frequency ◽  
Stress Sensitivity ◽  
Peak Ground Velocity ◽  
Ryukyu Islands ◽  
Plate Interface ◽  
Okinawa Island ◽  
Short Period ◽  
Ryukyu Arc ◽  
The Ryukyu Islands

Abstract Tremors and low-frequency earthquakes (LFEs), which occur in the plate interface, can provide useful information about the state of aseismic stress transfer in mega-earthquake fault zones. We estimated the distribution of stress sensitivity in the subducted plate interface by using triggered LFEs. Specifically, we detected LFEs in the Ryukyu Trench triggered by the surface waves of large teleseismic earthquakes by using the waveform records of broadband and short-period seismometers installed in the Ryukyu Arc. We selected a total of 45 teleseismic earthquakes with magnitudes of more than 7.5, which occurred between 2004 and 2017, for the analysis. We could detect the triggered LFEs for five teleseismic earthquakes. Then, we determined the hypocenters of LFEs by using the relative arrival times of LFEs for each station. The LFEs were distributed in the south of Okinawa Island and the Yaeyama area. Moreover, they were distributed around the source fault of the slow slip events. These were almost the same as the position of LFEs accompanying very low-frequency earthquakes (VLFEs). However, the epicenters of the triggered LFEs were concentrated near the locations of the most active LFE clusters accompanying VLFEs. This suggests that the sensitivity for inducing LFEs was higher near the most active clusters of the LFEs accompanying the VLFEs. The amplitudes of the triggered LFEs were proportional to the peak ground velocity of the surface waves. This indicates that the LFEs accompanying VLFEs are activated by stress acceleration in the Yaeyama and Okinawa areas and the triggered LFEs observed in these areas can be a result of the activation of the ambient tremors due to increased stress.

Seborgia cavernicola sp. nov. from a submarine cave on Okinawa Island, Ryukyu Islands, southwestern Japan (Crustacea, Amphipoda, Seborgiidae)

Zootaxa ◽  
2021 ◽  
Vol 4927 (1) ◽  
pp. 133-142
Author(s):  
MICHITAKA SHIMOMURA ◽  
YOSHIHISA FUJITA
Keyword(s):  
First Record ◽  
Ryukyu Islands ◽  
Key To Species ◽  
Okinawa Island ◽  
The Family ◽  
Submarine Cave

A new seborgiid, Seborgia cavernicola sp. nov. is described from a submarine cave in Okinawa Island, Ryukyu Islands as the first record of the family from Japan. This species differs from its congeners by the following combination of characters: body without microspinules; eyes fainted, without ommatidia; epimeral plates with posterodistal angle produced into pointed process; main flagellum of antennule 4-articulate; article 2 of main flagellum of antennule longest; propodus of gnathopod 2 as long as wide; gland cone of antenna directed anteriorly; maxilla bilobed; uropod 3 biramous; and telson without setae and setules. A key to species of the genus is provided. 

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