Monday, 1. June 2009, 12:27
Text by: Monika Rademacher
Photos by: Oliver Mengedoht
Translated by: Ulli Bauer
Scientific name: Chiromantes dehaani
Trivial name: kurobenkeigani (Japanese), mangrove crab
[attachment=8254]
Systematics: Domain: Eucaryota, kingdom: Animalia, subkingdom: Metazoa (multiple-celled animals), Eumetazoa (true tissue), grade: Bilateria, branch: Protostomia, infrakingdom: Ecdysozoa (molting animals), phylum: Arthropoda (jointed-leg invertebrates), subphylum: Crustacea, class: Malacostraca (higher crustaceans), superorder: Eucarida, order: Decapoda (ten-legged crayfish), suborder: Pleocyemata, infraorder: Reptantia, section: Brachyura (true crabs), superfamily: Grapsoidea, family: Sesarmidae (mangrove crabs), species: Chiromantes dehaani
[attachment=8255]
Origin/Range: Southeast Asia
[attachment=8256]
Further pics: http://www.panzerwelten.de/v/Chiromantes...s_dehaani/
Description: Olive, brown and purple shades form a color mixture on the rectangular carapace, which only shows its entire beauty when under lights. When the light is low, C. dehaani seems to be of a nearly uniform olive green. The claws are of a contrasting light coloration and are covered by many small whiteish granules. The lower leg segments show a dense hairlike growth (setae --> hairlike extensions of the cuticula, for taking up dew/moisture, amongst others), that looks pitch black and thus forms a striking contrast to the leg color.
[attachment=8257]
Sex differences: typical for crabs, the males have a narrow, pointed abdominal apron (pleon) and large pairing claws, the females have a wide, roundish pleon, which covers almost the entire abdomen.
[attachment=8258]
Male
Size: The carapace is at least 4 cm wide.
Life span: several years
Water temperature: tropical (approx. 20 to 28 °C, more active from 22 °C upwards)
Tank size/stock: A pair (1.1) or a group of three (1.2) in a well-structured aquaterrarium starting at 112 l (80x35x40cm).
When these crabs are kept in a group, there ought to be more females than males. Please do keep in mind even larger groups can only contain several males if all these crabs find enough room to stake out their territories.
Set-up: Aquaterrarium (aquarium with a land part) with wood, rocks, hardy plants; well-structured and with lots of hideouts (wood, rocks), tree leaves (as hideout and food). In the water: sand or gravel, on the land part sand, soil, a mix or terrarium humus - which is preferrable according to our experience as it hardly ever moulds.
[attachment=8259]
Food: Typical for crabs, they are omnivores.
• Leaves (the main staple of many crabs in nature; mostly oak and beech are fed, however, all European broadleaved tree leaves are possible, also Indian almond leaves), muck, water plants
• Vegetables/fruit: nearly all vegetables and fruit are suitable (peas, lettuce, cucumber, apple, zucchini, pear, banana, grapes, tomato, Brussels sprouts, bell peppers) except for parsley and beans or other kinds that contain Prussic acid or copper; carrots (boiled); potato and rice (boiled) or noodles (uncooked? Don't leave these in the tank for too long a time though, they can be the cause of turbid water and finally lead to a bacteria bloom and oxygen depletion); no citrus fruit due to their high acid content
• Dry food: Catfish tabs, fish (flake) food, food pellets, rabbit, guinea pig and chinchilla food pellets (without copper!), Spirulina tabs, crayfish tabs, Gammarus
• Frozen food: Black, glass and blood worms, Cyclops, brine shrimp, clam meat
• Live food: Earthworms (it's best to cut them into pieces though, or else these worms might burrow in the substrate, possibly also under water, die and rot there unnoticed until it's too late)
• Meat (rarely): Chicken bones with meat rests (rinsed well to prevent too much fat from getting into the terrarium)
• Fish: deep-frozen smelts et.al., tuna fish, sardines, herring etc. fresh or from a can (in their own juice, not in oil)
• Calcium: cuttlebone, smashed eggshells or powdered calcium in self-made food sticks
[attachment=8260]
Behavior: C. dehaani is very active in our aquaterrariums, independent of the time of day. Since they have fully adapted to their surroundings they hardly display flight behavior. The animals show themselves regularly and behave relatively peacefully towards other crab species of comparable size. When kept together with other crabs of similar size they display and take on aggressive postures from time to time, but do not show any motivation to incur more serious confrontations. They should not be kept together with significantly smaller crab species as they regard them as food. Snails are also cracked open and eaten from time to time, whereas they do not attack fish or dwarf shrimp.
[attachment=8261]
As they have a real positive influence on the aquaterrarium's climate, plants ought to be present on the land as well as in the water zones. These crabs do not eat plants, however, at times they might dig one or the other out when burrowing or walking around under water, thus it might be possible that you have to re-plant from time to time.
[attachment=8262]
This crab species has an immense urge to move and fulfills this often by daring climbing tours. Thus the tank you keep them in always has to be secured, they use any and all holes to break out, even those you think they'll never reach.
[attachment=8263]
However he might have gotten up there...
[attachment=8264]
[attachment=8265]
Emergency exit?
Reproduction: They belong to the unspecialized type; the females carry an egg clutch under their abdominal apron for three to four weeks, the clutch consisting of thousands of eggs. The larvae are released into brackish/sea water. There the larvae go through several zoea and megalopa stages before leaving the sea as young crabs taking to land.
According to a study {"Difference of Salinity Requirements among the Three Estuarine Crab Species Chiromantes dehaani, Helice tridens and H. japonica" by Bambang Irawan and Akihiro Kijima (1992)}, the zoean larvae of C. dehaani are quite tolerant of fresh water. Within a series of experiments, 100% of all zoea survived for ten days in fresh water, the same applied to those in various salinities (0.35 to 20 per mil). At a salinity of 35 per mil, 88% of the zoea survived in a timespan of ten days.
Socialization: Shrimp, snails (smaller specimens might be eaten), guppies and other livebearers, plecs; please abstain from co-housing them with crayfish.
Our crab has been living in a 1 meter tank with second-level land parts together with two other crab species. In this community aquaterrarium there are five crabs in all (the Chiromantes dehaani together with two Sesarmops intermedium and two Neosarmatium meinerti) living peacefully together, this works surprisingly well. We have never been able to observe serious clashes; from time to time smaller confrontations take place during whose course manifold aggressive postures are assumed, but up to now there have been no casualties, nor have individuals been domineered over.
[attachment=8266]
Chiromantes dehaani to the left, Sesarmops intermedium to the right
Additional information:
• Chiromantes dehaani were observed in their original habitats in Japan in the same areas as Sesarmops intermedium, amongst others. Thus the cohabitation of these two species is something also found in their natural biotopes.
Photos by: Oliver Mengedoht
Translated by: Ulli Bauer
Scientific name: Chiromantes dehaani
Trivial name: kurobenkeigani (Japanese), mangrove crab
[attachment=8254]
Systematics: Domain: Eucaryota, kingdom: Animalia, subkingdom: Metazoa (multiple-celled animals), Eumetazoa (true tissue), grade: Bilateria, branch: Protostomia, infrakingdom: Ecdysozoa (molting animals), phylum: Arthropoda (jointed-leg invertebrates), subphylum: Crustacea, class: Malacostraca (higher crustaceans), superorder: Eucarida, order: Decapoda (ten-legged crayfish), suborder: Pleocyemata, infraorder: Reptantia, section: Brachyura (true crabs), superfamily: Grapsoidea, family: Sesarmidae (mangrove crabs), species: Chiromantes dehaani
[attachment=8255]
Origin/Range: Southeast Asia
[attachment=8256]
Further pics: http://www.panzerwelten.de/v/Chiromantes...s_dehaani/
Description: Olive, brown and purple shades form a color mixture on the rectangular carapace, which only shows its entire beauty when under lights. When the light is low, C. dehaani seems to be of a nearly uniform olive green. The claws are of a contrasting light coloration and are covered by many small whiteish granules. The lower leg segments show a dense hairlike growth (setae --> hairlike extensions of the cuticula, for taking up dew/moisture, amongst others), that looks pitch black and thus forms a striking contrast to the leg color.
[attachment=8257]
Sex differences: typical for crabs, the males have a narrow, pointed abdominal apron (pleon) and large pairing claws, the females have a wide, roundish pleon, which covers almost the entire abdomen.
[attachment=8258]
Male
Size: The carapace is at least 4 cm wide.
Life span: several years
Water temperature: tropical (approx. 20 to 28 °C, more active from 22 °C upwards)
Tank size/stock: A pair (1.1) or a group of three (1.2) in a well-structured aquaterrarium starting at 112 l (80x35x40cm).
When these crabs are kept in a group, there ought to be more females than males. Please do keep in mind even larger groups can only contain several males if all these crabs find enough room to stake out their territories.
Set-up: Aquaterrarium (aquarium with a land part) with wood, rocks, hardy plants; well-structured and with lots of hideouts (wood, rocks), tree leaves (as hideout and food). In the water: sand or gravel, on the land part sand, soil, a mix or terrarium humus - which is preferrable according to our experience as it hardly ever moulds.
[attachment=8259]
Food: Typical for crabs, they are omnivores.
• Leaves (the main staple of many crabs in nature; mostly oak and beech are fed, however, all European broadleaved tree leaves are possible, also Indian almond leaves), muck, water plants
• Vegetables/fruit: nearly all vegetables and fruit are suitable (peas, lettuce, cucumber, apple, zucchini, pear, banana, grapes, tomato, Brussels sprouts, bell peppers) except for parsley and beans or other kinds that contain Prussic acid or copper; carrots (boiled); potato and rice (boiled) or noodles (uncooked? Don't leave these in the tank for too long a time though, they can be the cause of turbid water and finally lead to a bacteria bloom and oxygen depletion); no citrus fruit due to their high acid content
• Dry food: Catfish tabs, fish (flake) food, food pellets, rabbit, guinea pig and chinchilla food pellets (without copper!), Spirulina tabs, crayfish tabs, Gammarus
• Frozen food: Black, glass and blood worms, Cyclops, brine shrimp, clam meat
• Live food: Earthworms (it's best to cut them into pieces though, or else these worms might burrow in the substrate, possibly also under water, die and rot there unnoticed until it's too late)
• Meat (rarely): Chicken bones with meat rests (rinsed well to prevent too much fat from getting into the terrarium)
• Fish: deep-frozen smelts et.al., tuna fish, sardines, herring etc. fresh or from a can (in their own juice, not in oil)
• Calcium: cuttlebone, smashed eggshells or powdered calcium in self-made food sticks
[attachment=8260]
Behavior: C. dehaani is very active in our aquaterrariums, independent of the time of day. Since they have fully adapted to their surroundings they hardly display flight behavior. The animals show themselves regularly and behave relatively peacefully towards other crab species of comparable size. When kept together with other crabs of similar size they display and take on aggressive postures from time to time, but do not show any motivation to incur more serious confrontations. They should not be kept together with significantly smaller crab species as they regard them as food. Snails are also cracked open and eaten from time to time, whereas they do not attack fish or dwarf shrimp.
[attachment=8261]
As they have a real positive influence on the aquaterrarium's climate, plants ought to be present on the land as well as in the water zones. These crabs do not eat plants, however, at times they might dig one or the other out when burrowing or walking around under water, thus it might be possible that you have to re-plant from time to time.
[attachment=8262]
This crab species has an immense urge to move and fulfills this often by daring climbing tours. Thus the tank you keep them in always has to be secured, they use any and all holes to break out, even those you think they'll never reach.
[attachment=8263]
However he might have gotten up there...
[attachment=8264]
[attachment=8265]
Emergency exit?
Reproduction: They belong to the unspecialized type; the females carry an egg clutch under their abdominal apron for three to four weeks, the clutch consisting of thousands of eggs. The larvae are released into brackish/sea water. There the larvae go through several zoea and megalopa stages before leaving the sea as young crabs taking to land.
According to a study {"Difference of Salinity Requirements among the Three Estuarine Crab Species Chiromantes dehaani, Helice tridens and H. japonica" by Bambang Irawan and Akihiro Kijima (1992)}, the zoean larvae of C. dehaani are quite tolerant of fresh water. Within a series of experiments, 100% of all zoea survived for ten days in fresh water, the same applied to those in various salinities (0.35 to 20 per mil). At a salinity of 35 per mil, 88% of the zoea survived in a timespan of ten days.
Socialization: Shrimp, snails (smaller specimens might be eaten), guppies and other livebearers, plecs; please abstain from co-housing them with crayfish.
Our crab has been living in a 1 meter tank with second-level land parts together with two other crab species. In this community aquaterrarium there are five crabs in all (the Chiromantes dehaani together with two Sesarmops intermedium and two Neosarmatium meinerti) living peacefully together, this works surprisingly well. We have never been able to observe serious clashes; from time to time smaller confrontations take place during whose course manifold aggressive postures are assumed, but up to now there have been no casualties, nor have individuals been domineered over.
[attachment=8266]
Chiromantes dehaani to the left, Sesarmops intermedium to the right
Additional information:
• Chiromantes dehaani were observed in their original habitats in Japan in the same areas as Sesarmops intermedium, amongst others. Thus the cohabitation of these two species is something also found in their natural biotopes.