Author: Monika Rademacher (Ygra), Photos: Oliver Mengedoht (Beastiependent), Translator: Ulli Bauer
The original description (in German) can be found here: http://www.panzerwelten.de/forum/showthread.php?tid=5
GEOSESARMA SP. "Vampire" (Vampire crab)
Scientific name: Geosesarma sp.
Trivial name: Vampire crab
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), genus: Geosesarma, species: Geosesarma sp. (not denominated yet)
Origin/Range: South-East Asia
Further photos: http://www.panzerwelten.de/v/Geosesarma/Vampirkrabben/
Description: multi-colored, whereas the individual colors occur in the most various combinations. The pincers and facial front tend to be of a light to dark purple, the carapace varies from reddish to blue tints, the legs are also of a color within this spectrum. Often the back of these crabs shows a large yellowish to white-colored spot, however, there are also vampire crabs that do not have it at all. The neon orange eyes are a striking characteristic, however, there are also some exceptions here, one of our crabs has claret red eyes.
Sex differences: Typically for crabs, the males have a narrow abdomen and the females a wide one, which nearly covers the entire underside.
Size: up to at least 2 cm width (measured on the carapace)
Life span: ? (several years)
The variable coloration can be seen clearly.
Water temperature: tropical (about 20 to 28 °C, more active from 24 °C upwards)
Size of the aquaterrarium/stocking: starting at 25 cm for a pair, however, keeping small group in 60 cm upwards is preferrable, if possible there should be more females than males.
Set-up: Aquaterrarium with a larger land part; well-structured with various levels for climbing, hiding-places and a substrate allowing them to dig burrows; plants (also hanging plants), mosses.
Food: apparently they are primarily carnivores
• Frozen food: mosquito larvae, cyclops, artemia, mussel meat
• Live food: earthworms (it's best to cut them into pieces in order to prevent the worms from digging in – even under water! –, drowning and rotting unnoticed), gammarus, shrimp, snails
• Fish: deep-frozen smelts et.al., tuna fish, sardines, herring et.al. either fresh or from a can (in their own juice, not in oil)
• Other: sporadically they also eat granular and flake food
With a flour worm.
Behavior: Relatively peaceful, like to sit on or close to each other, their keeping requirements vary strongly. E.g. there are crabs that exclusively sit on the land parts, others are mostly in the water or sit on high points with direct water contact. What is striking is that they seem to be location-bound, the crabs look for a place in the aquaterrarium and, when they have found one they like, they do not walk far away.
Only seldomly they will search for food actively, these crabs mostly take food directly within reach or which they stumble upon on their short rambles.
Reproduction: Specialized reproduction in fresh water with entirely developed offspring instead of larvae. The females carry relatively large eggs (> 1mm).
Socialization: With shrimp, snails (smaller specimens can get eaten from time to time).
On the land part the crabs soon go into hiding.
• Our first pair of this species unfortunatly hasn't survived.
They were kept in a terrarium with a water bowl as both crabs decidedly preferred to sit on the land part. The male died after a relatively short time after its arrival here, it had not eaten from the beginning and seemed to prepare for a molt, which it couldn't carry out successfully. The female molted but was very weak afterwards so that it died 12 hours later, too. Both crabs were extremely small when we got them.
• In the meantime, five new crabs (4,1) have found a home in one of our 60 cm aquaterraria. They are quite peaceful among each other and are overall pretty quiet animals which hardly ever leave their location, and they are carnivores without exception. They are offered vegetable food daily, which they do not eat. They are rather nervous and go into hiding as soon as they see movement outside the aquaterrarium, however, they take food offered with a pair of tweezers. Two of the crabs exclusively sit in the burrows they have dug in the land part, three are always in the water or on higher spots that allow them to keep water contact with their feet at least.
A few days before our last male died a second female came to us, in the meantime they have finally produced offspring.
• In the mailing list of AG Wirbellose several participants reported that vampire crabs actively hunt live Gammarus and Hyalella azteca (Mexican freshwater shrimp).