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העולם התת ימי
{ 27 images }
Created 5 Jan 2011
תמונות תת ימיות מים סוף וים תיכון
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סרטן נזיר.JPG
מדוזה חוטית נודדת.JPG
תמנון בשמש.jpg
מרקו הדולפין.tiff
עטלף ים.jpg
צב ים וצולל.jpg
חשופית פלבלינה.jpg
bluespotted ribbontail- Taeniu3.jpg
Lionfish - Pterois- 15.jpg
Chromodoris annulata-8.JPG
Lionfish - Pterois- 17.tif
20120514_7248.JPG
Yachting Turkey-_HGI0324.tiff
Butterflyfish - Chaetodontidae.jpg
HGI_0682.jpg
HGI_0698.jpg
Ctenophora, comb jellies-1.JPG
sea horse- hippocampus14.jpg
פילוריזה.jpg
Portunus pelagicus-blue crab17.jpg
Portunus pelagicus-blue crab28.jpg
Commercial Diver-13.jpg
nizzan ship wreck-28.jpg
SS Thistlegorm-11.jpg
הצוללת שירה
סידר פרייד.jpg
HGI_2042.jpg
![Portunus pelagicus, also known as the flower crab, blue crab, blue swimmer crab, blue manna crab or sand crab, is a large crab found in the intertidal estuaries of the Indian and Pacific Oceans (Asian coasts) and the Middle-Eastern coast of the Mediterranean Sea. The name "flower crab" is used in east Asian countries while the latter names are used in Australia. The crabs are widely distributed in eastern Africa, Southeast Asia, East Asia, Australia and New Zealand.The males are bright blue in colour with white spots and with characteristically long chelipeds, while the females have a duller green/brown, with a more rounded carapace. The carapace can be up to 20 centimetres (7.9 in) wide.<br />
P. pelagicus commonly enters estuaries for food and shelter. Its life cycle is dependent on estuaries as the larvae and early juveniles use these habitats for growth and development. Prior to hatching, the female moves into shallow marine habitats, releases her eggs and the newly hatched zoea I larvae move into estuaries. During this time they feed on microscopic plankton and progress from the zoea I stage to the zoea IV stage (approximately 8 days) and then to the final larval stage of megalopa (duration of 4-6 days). This larval stage is characterised by having large chelipeds used to catch prey. Once the megalopa metamorphoses to the crab stage they continue to spend time in estuaries which provides a suitable habitat for shelter and food. However, evidence has shown that early juveniles cannot tolerate low salinities for extended periods, which is likely due to its weak hyper-osmoregulatory abilities.[4] This may explain their mass emigration from estuaries to seawater during the rainy season. Male Portunus pelagicus are believed to become more territorial in colder water. This may explain why male crabs are rarely sighted within a close proximity to each other in more temperate waters; it also may explain why their female counterparts seem more prolific in these such areas.](https://archive.hagainativ.com/img-get2/I0000JI5X9g8VKHE/fit=188x188/fill=/g=G0000JJYx4URa2RY/I0000JI5X9g8VKHE.jpg)
