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Geosesarma dennerle — Purple Vampire Crab

The Purple Vampire Crab is a small terrestrial crab from Indonesia, valued for its purple coloration and strongly contrasting yellow eyes. Despite its English trade name, it is not a fish but a crustacean adapted to life between damp land and freshwater. Geosesarma dennerle therefore requires a properly designed paludarium rather than a conventional aquarium. Its discreet behavior, especially during daylight, becomes more interesting to observe under subdued lighting. This species is uncommon in the trade, and the specimens offered are wild-collected.

General species description

Geosesarma dennerle is a small crab in the genus Geosesarma, a group of terrestrial crabs from Southeast Asia. It occupies damp habitats near small streams but spends most of its time out of the water. A suitable setup should provide a mainly terrestrial area, shelters and easy access to clean freshwater. The species is generally more active at dusk and during the night. Males may become territorial, especially in confined spaces, so several individuals require enough floor area and numerous hiding places.

Geographical origin and biotope

Geosesarma dennerle originates from Indonesia, where it is associated with damp terrestrial areas on the island of Java. Its biotope includes leaf litter, roots, stones and shaded banks along small forest streams. The available water is fresh and is used for hydration and reproduction. In captivity, its natural conditions are best approximated with a ventilated paludarium, high humidity, an emergent land area and a shallow pool. The enclosure must be escape-proof because this crab climbs readily.

Precise location and local name

Available information places Geosesarma dennerle on Java, Indonesia. Detailed locality information and a commonly used local name are not included here. In the aquarium trade, the name Purple Vampire Crab is widely used. This designation is mainly descriptive, referring to the purple body coloration and pale eyes. As with several small terrestrial crabs, trade identification should be checked carefully because related Geosesarma species may display similar colors.

Appearance and physical characteristics

The body of Geosesarma dennerle is compact, with a dark purple to violet carapace and yellow to orange eyes that stand out clearly. The legs are usually violet to brownish, while the claws may show lighter shades. Adult size remains small, with the carapace reaching about 3 cm. Coloration can vary with age, sex, health and lighting conditions. A well-formed carapace, normal movement and intact appendages are useful general indicators of a healthy specimen.

General diet

Geosesarma dennerle is an opportunistic omnivore and detritivore. Its diet can include sinking crustacean pellets, meaty foods, small invertebrates and plant matter. Blanched vegetables, clean dry leaves and calcium-rich foods are useful additions. Calcium supports carapace development and renewal. Remove leftovers before they decompose to protect water quality. A varied diet offered in small portions, mainly in the evening, is preferable to large and irregular feedings.

Essential data

• Name of the original river:
• Local name used:
• Origin of the scientific name: Geosesarma dennerle
• Etymology of the complete name: Geosesarma combines geo, meaning earth, with Sesarma, a crab genus name; dennerle honors Dennerle.
• Common/vernacular names: Purple Vampire Crab
• Family: Sesarmidae
• Subfamily: Sesarminae
• Name pronunciation: jee-oh-seh-sar-ma den-ner-lay
• Discovery: Hendrik W. B. Ng, Christoph D. Schubart and Chris Lukhaup, 2015
• Maximum adult size: About 3 cm carapace length
• Water temperature and pH: About 22 to 28 °C; approximately pH 6.5 to 8.0
• Stream appearance and surrounding vegetation: Shaded small streams, leaf litter, roots and humid forest vegetation
• Typical tankmates: Best maintained in a species setup; avoid fish and large invertebrates
• Temperament and behavior: Generally discreet, crepuscular and nocturnal; males may be territorial
• Water depth: Shallow aquatic area with a large terrestrial section
• Sexual dimorphism: Males often have a narrower abdomen; females are generally broader
• Bottom structure and flow: Damp substrate made of sand, soil, leaves and shelters; calm to gently moving water

In your paludarium

Success with Geosesarma dennerle begins with a fully secure paludarium, since gaps and cables can provide escape routes. Provide a large, damp terrestrial area, several hiding places, shallow freshwater and good ventilation. Maintain high humidity without keeping the substrate permanently waterlogged. Feed the group in the evening, monitor molts and remove uneaten food. Because the species is uncommon and offered here as a wild-collected animal, gradual acclimation and stress reduction are especially important.