Geosesarma Explained

Geosesarma is genus of small freshwater or terrestrial crabs, typically less than 10mm across the carapace.[1] They live and reproduce on land with the larval stages inside the egg. They are found from India,[2] through Southeast Asia, to the Solomon Islands and Hawaii.

In the pet trade, they are sometimes called vampire crabs. This has nothing to do with their feeding habits, but rather with the bright, contrastingly yellow eyes of some Geosesarma species.

Species

Geosesarma contains these species:[3]

As of March 2015, professor Peter Ng of National University of Singapore has named 20 Geosesarma species, and he "has another half a dozen or so newly collected Geosesarma species from Southeast Asia in his lab, and these species still need to be named and described."[5] [6]

Threats

Geosesarma dennerle and Geosesarma hagen, both originally from Java, are threatened by illegal overcollection for the aquarium trade.[7]

Geosesarma in captivity

Geosesarma (Vampire Crabs) have become extremely popular in the exotic animal hobby over recent years. However there is a lot of misconception about how to best keep them. They are often mistaken for aquatic crabs and kept in unsuitable conditions with excessive amounts of water, which will ultimately leads to shortened life spans. The ideal captive environment for Geosesarma species is one that consists of 80% land and 20% water. With natural soil and dense planting making up the majority of the terrestrial area. As these species live in the ground, primarily in burrows, soil is vital for their well being, stress reduction and breeding. [8]

While they also require water to survive, it is primarily used for molting and hydration. Both of which can easily be met with a small water volume, enough to cover their entire body completely will suffice. However it is advised to have a depth of at least double their body height to account for any evaporation. Without access to water Geosesarma crabs will dry out and perish.

It is also important never to mix any other species of Geosesarma together. While they are a semi social species of crab, they are extremely aggressive towards other species and will almost always kill other species present in their territory.

Environmental Parameters for keeping Geosesarma crabs in captivity

Water temperature: 22–25°C (71–78°F)

Air Temperature: 22–28°C (71–82°F)

PH: Between 7.5–8.0

KH (carbonate hardness): Between 0–10

GH (general hardness) Between 4–16

Ammonia: 0

Nitrite: 0

Nitrate: Lower than 20 ppm

Notes and References

  1. Book: Hartnoll, Richard G. . [{{google books|plainurl=yes|id=RR09AAAAIAAJ|pg=PA35}} Biology of the Land Crabs ]. . 1998 . 9780521306904 . Warren W. Burggren . 6–54 . Evolution, systematics, and geographical distribution . Brian R. McMahon.
  2. Web site: Pati . S. K. . Dev Roy . M. K. . Sharma . R. M. . Freshwater crabs . dead . https://web.archive.org/web/20130917025112/http://zsi.gov.in/checklist/freshwater_crabs.pdf . September 17, 2013 . November 8, 2012 . Checklist of Indian fauna . .
  3. Geosesarma . 2225760.
  4. Shy . Jhy-Yun . Ng . Peter K. L. . 2019 . Geosesarma mirum, a new species of semi-terrestrial sesarmid crab (Crustacea, Decapoda, Brachyura) from central Taiwan . ZooKeys . 858 . 1–10 . 10.3897/zookeys.858.35198 . 1313-2989 . 6614171 . 31312087. free .
  5. Web site: Mystery of the 'Vampire Crabs' Solved. Agata. Blaszczak-Boxe. March 19, 2015. livescience.com.
  6. News: Blaszczak-Boxe . Agata . 19 March 2015 . Mystery of the 'Vampire Crabs' Solved . en . . 2021-02-11.
  7. Web site: Mahbu . Amri . March 23, 2015 . New Species of Javan Vampire Crabs Face Potential Exploitation .
  8. Web site: Gusmeroli . Jascha . September 19, 2024 . Everything you need to know about Geosesarma Vampire Crabs . www.indoorecosystem.net.

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