Vampire Crab Paludarium Setup
Vampire crabs (Geosesarma) are small land-dwelling crabs that breed without a larval stage. This guide covers humidity, temperature, a small water area, food and wild collection.
What vampire crabs are
"Vampire crab" is a trade name for small land-dwelling crabs of the genus Geosesarma (family Sesarmidae). According to Wikipedia, the genus occurs in India, Indonesia, Malaysia, Thailand, the Philippines, the Solomon Islands and Hawaii, and most species measure less than 10 mm across the carapace. The name refers to the bright yellow eyes of some species, not to their feeding habits. This guide covers housing in a paludarium; the general Aquairi paludarium guide explains how such land-and-water enclosures are built.
Species in the trade and newly described taxa
The genus is still being described. Wikipedia counts well over 60 species, and new ones keep appearing in the peer-reviewed literature, for example Geosesarma sodalis from a limestone cave in Sarawak (ZooKeys, 2021), Geosesarma garutense from West Java (Zootaxa, 2022) and Geosesarma wongi from Peninsular Malaysia (ZooKeys, 2026). The two colour forms most often sold, a cream-and-violet crab and a dark brown-and-orange crab, were in the aquarium trade for years before science knew where they came from; dealers variously claimed Sulawesi, Java, Krakatau or the Riau Islands. In 2015, Ng, Schubart and Lukhaup described them in the Raffles Bulletin of Zoology as Geosesarma dennerle and Geosesarma hagen and showed that both are native to central Java, Indonesia, in separate valleys about 10.5 km apart. Animals sold under trade names may therefore belong to described species, undescribed species or mixtures, and the label alone does not confirm identity.
A mostly terrestrial animal
Geosesarma species live and reproduce on land. In central Java, G. dennerle lives on the slopes of a small valley, under and between rocks among dense vegetation, and sometimes digs burrows in loose ground at the edge of a creek; G. hagen was found hiding under dense ground cover on a hillside with many small trickles of water. On land the crabs breathe with a specialised tissue on the inside of the gill chamber (the Verwey tissue), which acts as a rudimentary lung, but they can also use their gills underwater. Researchers keeping G. hagen observed the crabs mostly on land, hidden in shallow burrows, under wood and beneath moss, yet occasionally fully submerged in the water dish for several hours.
Humidity, temperature and layout
No formal husbandry standard for the genus was found. The most concrete published reference is the housing used in a 2026 bioRxiv preprint (not yet peer-reviewed) on G. hagen respiration:
- A room held at 80% relative humidity and an average of 26 °C, with a 12-hour light–dark cycle.
- About 5 cm of moist soil mixed with sphagnum moss as substrate.
- A small shelter, plus a small, shallow water dish with a thin layer of mineral clay.
- Water prepared from distilled water remineralised with a mineral (GH/KH) supplement.
The same study used 21 °C and 28 °C for experiments as a range of temperatures the species meets in nature, and cites average surface temperatures in Java of 31 °C, ranging from 16 °C to 41 °C. It found that respiration and metabolism rise by about 52% for every 10 °C increase (Q10 = 1.52); a companion 2024 EcoEvoRxiv preprint by the same group suggests that small females are the most susceptible to warming. In a paludarium this translates to a layout that is mostly moist land with hiding places and moss, and a small, shallow water area the crabs can climb out of easily.
Feeding
In the wild, G. dennerle eats mainly small terrestrial insects such as grasshoppers, and probably also chironomid larvae and plant detritus; Wikipedia describes the diet as insects and plant matter. In the research colony, crabs received fruit flies (Drosophila hydei) dusted with a calcium supplement three times a week and three pinhead crickets twice a week. Live insects are therefore the core food; frozen foods are not described in the sources consulted.
Breeding without a larval stage
Unlike fiddler crabs and most other crabs, Geosesarma does not release planktonic larvae: the larval stages are completed inside the egg. Wikipedia reports that a female G. dennerle carries around 20–80 fertilised eggs for about a month, that the young hatch as fully formed miniature crabs and disperse independently, and that the species matures at about six months. Because there is no marine larval phase, the young do not need sea water at any stage. The Aquairi guide on invertebrate moulting covers growth and moulting.