"Don't get too fat, otherwise you will let people eat it" - the "famous line" in Ghibli's masterpiece "Spirited Away" not only makes this movie picture a temporary screen meme, but also tells the bitterness of today's protagonist "Coconut Crab".
The coconut crab birgus latro, which can weigh more than 3 kilograms in adults, is the world's largest terrestrial crustacean and was once widely distributed in the Indian Ocean to the islands of the South Pacific. Whether it is Chinese name or the English name coconut crab, it is inevitable that we will have a picture of a "giant crab that eats coconut meat with a powerful tongs crushing coconuts".
Calendar Girl: Actually, coconut crabs are not crabs. It belongs to the same crooked-tailed lower order as the hermit crab and the rock crab, it has only six steps, and when it was a child, like a hermit crab, it burrowed into the shell as a defense.
However, coconut crabs are not just vegetarians, and National Geographic magazine once recorded a video of coconut crabs sharing the carcass of a pig with many hermit crabs on the beach on Niku Marolo Island. In addition, Mark Laidre, a biologist at Dartmouth College in the United States, has recorded in the Chagos Archipelago in the Indian Ocean that coconut crabs climb trees, not to find fruit, but to attack a seabird, break its wings, and eat it as a supper.
Delayed photography, hermit crabs and coconut crabs feed on carcasses | national geographic / youtube
Coconut crabs with a clamping force comparable to the bite force of lions, in addition to opening the coconut, broken bones and flesh are also easy, so they occasionally play the role of "scavengers". Even on some tropical islands, there are rumors of "whispering people".
Coconut crabs prefer a humid and cool environment, mostly in the rock crevices, underground caves and low vegetation between the forest, and are more active at night. Especially in areas with fewer people and more crabs, they will appear near the coastline even during the day to feed. So contrary to rumors, on food-starved tropical islands, the slow-moving coconut crab is a source of protein that locals see as easy to catch and delicious.
Coconut crab on the branches | Zhang Xiao Bee
The nearest coconut crab is distributed in China's Hainan Province, Taiwan Province, and parts of the Ryukyu Islands now under the jurisdiction of Japan, and human economic activities are gradually encroaching on the natural environment on which they depend, and the number of wild populations is decreasing, gradually becoming a rare "dream creature". Although it is no longer the era of lack of food and clothing, some people still regard coconut crabs as rare delicacies and even novel pets, resulting in a small number of coconut crabs being poached and trafficked as a vulnerable species.
In Okinawa Prefecture, Japan, where I live, coconut crabs are mainly distributed in the sparsely populated islands and in the northern part of the island, which has preserved a wide range of pristine vegetation. Although coconut crabs have adapted to life on land, they still cannot completely leave the sea and hide in the mountains and forests, away from humans, mainly living in the vegetation cover area within 1 to 3 kilometers along the coastline, feeding on pandanus tree fruits, small birds and animal carcasses, etc.
When the autumn wind blows north, the temperature gradually decreases, and the frequency of the coconut crab gradually decreases, hiding in the limestone cave in the woods for the winter, waiting for the weather to warm up. By the time Okinawa opens to the sea in April, coconut crabs have also begun to increase the frequency of foraging for food, storing nutrients for the summer breeding season.
Coconut crabs in the northern part of the main island of Okinawa | Senno
Okinawa is geographically norther than Fujian and Taiwan, almost at the same latitude as Wenzhou, Zhejiang, and although it benefits from the humid and warm subtropical marine climate brought by the warm currents in Japan, it is also almost the northern limit of coconut crab life in the northern hemisphere. Because of this, the breeding season of coconut crabs here comes later and is shorter, from June to August. During this time, adult coconut crabs will look for the opposite sex and frequently hug each other. The male crab leans upwards and presses its abdomen against the abdomen of the female crab in order to glue the white gel-like seminal wrap of the male crab's abdomen near the reproductive hole in the female crab's abdomen. When the female crab lays eggs from the reproductive hole, the sperm packet is used to fertilize the eggs outside the body, and the fertilized eggs are attached to the hairy abdominal limbs for a period of about 1 month.
The seminal bun in the abdomen of the male crab | with the female crab carrying the egg Ishigaki Branch of the Seokai-ku Shuiku Research Institute
After that, the female coconut crab will leave the vegetation area and walk slowly towards the sea, releasing the offspring into the sea. At this time, the coconut crab larvae, in the flea zoea to the late larval stage (glaucothoe), like other larvae of hermit crabs commonly found by the sea, will spend 3 to 4 weeks in the sea in plankton state, and then find a small conch shell, carrying it ashore until it grows to several centimeters long. It is precisely because of this process that the coconut crab population can spread with the currents of the sea and not be trapped in an isolated island.
The flea-like larvae and post-larvae of the Kamchatka quasi-stone crab paraalithodes camtschaticus, it belongs to the order Perverse-tailed | like the coconut crab anya dunham et al. / journal of the marine biological association of the uk (2006)
After a period of "hermit crab"," the coconut crab gradually grew up and showed a different physique from other hermit crabs, and the suitable conch was difficult to find, so it began to build its own hard shell, slowly growing to the largest crustacean on land like its parents. How slow is the coconut crab growing? Generally speaking, it takes 10 years for female coconut crabs to grow to sexual maturity (about 20 mm chest length), 10 years for male crabs to be sold in the market for "edible size (chest length of about 40 mm)", and more than 25 years for female crabs. If you are lucky enough to meet a giant coconut crab of four or five kilograms, the probability is that it is more than half a hundred years old.
The slow growth makes it difficult for coconut crabs to recover in the wild population, which is exacerbated by the pursuit of "large coconut crabs" by humans. Male coconut crabs are about 1.5 times the size of female coconut crabs of the same age, so large male coconut crabs are more likely to become plate meals and caged treasures.
Live coconut crab | sold at the fresh fish market on the main island of Okinawa Senno
Under normal environmental conditions, more mature and strong male coconut crabs are more likely to win the competition and get more mating opportunities. They have a larger sperm volume and are able to leave their offspring with the greatest probability. However, nowadays, human capture, so that the wild coconut crabs show more females and fewer males, strong males and females are weak, weak males lack sperm and unbalanced sex ratio, male miniaturization and low birthrate, may have become the biggest obstacle to the recovery of coconut crab population.
In view of the decline in the population of coconut crabs in the wild, Taiwan Province of China has included coconut crabs in the list of conservation species in Taiwan. In June 2014, Ishigaki Island in Okinawa Prefecture promulgated the "Ishigaki City Coconut Crab Protection Ordinance", which not only designates the coconut crab protection area, but also stipulates that 12 to 8 months is a total ban on fishing, and only from September to November, male crabs with a chest length of 40 to 55 mm can be moderately caught outside the protected area, and artificial breeding of coconut crabs is carried out in research institutes on the island.
Although the protection is still insufficient, it is not completely hopeless. In particular, in recent years, Okinawa has gradually adopted the "coconut crab" as a natural tourism resource, and has successively carried out night safaris on the main island and outlying islands to find coconut crabs. Perhaps when the coconut crab, which lives freely in the wild, can become a long-term and stable source of economic income, the local people are willing to give up catching and selling coconut crabs for temporary profits. If one day coconut crab becomes a common species on tropical islands, perhaps those "exotic" players who are curious to meet their own ostentatious mentality will also dispel their thoughts? Instead of seeing you at the dinner table, it's better to look forward to meeting these interesting coconut knockers in the wild!
This article is from the species calendar, welcome to forward
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