Vampire Crab

The vampire crab is a small crab much loved in the hobby for its bright yellow eyes and dark purple body. Its shell is about 2 cm and its leg span around 5 cm. For many years it was sold as "Geosesarma sp. Vampire"; in 2015 it was scientifically described as Geosesarma dennerle.

This species is semi-terrestrial: it spends most of its time on land among damp moss and leaves, and enters the water only to wet itself, drink and feed. In a normal aquarium it can drown or escape; the right setup is a humid paludarium. Its relative, the red devil crab (Geosesarma hagen), needs similar care.

It lives in the rainforests of Java, on the damp forest floor near streams and springs. It hides under roots, rocks and accumulations of leaves.

• Setup: A paludarium: about three quarters of the floor land and one quarter fresh water 3–5 cm deep. An easy exit ramp from the water section is essential.
• Humidity: High humidity; the land side is covered with damp moss, roots and dried leaves. Mist regularly.
• Temperature: 22–26°C; above 28°C for long periods is harmful.
• Lid: A tight lid is essential; it climbs glass and cables.
• Hiding places: A cave for each individual; it hides while molting.

Omnivorous. It eats sinking tablets, shrimp food, frozen bloodworms, small insects (fruit flies, baby crickets), blanched vegetables and pieces of fruit. Remove leftover food the next day; it molds quickly in a humid environment.

Nocturnal; it hides during the day. It is territorial toward its own kind, especially between males. Given the chance it catches small shrimp and very small fish; that is why dwarf shrimp are not put in the water section.

Good companions: It is best kept with its own species. Snails in the water section usually have no problems.

Avoid: Fish, dwarf shrimp, other crab species, frogs.

One male and two or more females is the most harmonious arrangement. More than one male can only be housed in a large paludarium with plenty of hiding places. The colony reproduces on its own; when space becomes tight, individuals need to be separated.

There is no larval stage. The female carries the eggs under her abdominal flap; fully formed tiny crabs hatch from the eggs and stay under the mother's abdomen for a while. For this reason it can be bred at home in fresh water. Because adults may eat the young, dense hiding places are needed.

• Drying out: Low humidity and escapes are the most common causes of death.
• Molting: It is defenseless during this period; do not disturb it.
• Overheating: Plan for cooling in summer.

Males have a narrow, roughly triangular abdominal flap; females have a wide, rounded one. Males' claws are usually slightly larger.