Red Devil Crab (Geosesarma hagen) – A Small Devil with Character
Red Devil Crab (Geosesarma hagen Ng, Schubart & Lukhaup, 2015) is a terrestrial crab commonly found in commerce and home cultures. It is one of the most recognizable crabs of the Geosesarma genus, reaching a size of 3 to 5 cm. Although it was only described scientifically in 2015, it had already been raised in homes and was common in commerce. It is most similar to species such as Geosesarma dennerle Ng, Schubart & Lukhaup, 2015, Geosesarma noduliferum De Man, 1892, and Geosesarma bicolor Ng and Davie, 1995.
Habitat
This species is endemic to central Java, Indonesia.
Naming
In the trade, it is known by various names, including Geosesarma rot (red in German).
What Does the Red Devil Crab Look Like?
The red devil crab (Geosesarma hagen) has dark brown or black legs. Its carapace is clearly divided into two colors: dark brown or black and red or orange. The pincers are red or orange, and the eyes are yellow or white-yellow. Some individuals have less intense red and orange colors. The coloration of crabs depends on individual characteristics, the time before molting, and age. Young individuals are brown with yellow or orange spots, but as they grow, their coloration changes. Adult red devil crabs are known to have orange-brown coloration and may differ in appearance. There are also individuals with a dominant red or orange color on the entire body.
Living Conditions
This upland species inhabits the tropical forest floor near small watercourses and is closely associated with the aquatic environment. It hides among stones, roots, in mulch, or digs burrows in loose soil. Young individuals spend more time in and around water. Geosesarma hagen has also been found away from bodies of water, deep in the forest, indicating a preference for a more terrestrial lifestyle.
What Do Red Devil Crabs Eat?
They mainly feed on small invertebrates and enjoy actively hunting them. They also consume plant parts and carrion but prefer freshly hunted prey. In captivity, it is worth feeding them cricket hatchlings, cockroach hatchlings, chironomid larvae, and other aquatic invertebrate larvae. Aquarium fish foods such as Tropical Ichtio-vit, Tropical Bio-vit, and Tropical Ovo-vit also work well. Fruits like bananas and mangoes can add variety to their diet. In conclusion, the red devil crab (Geosesarma hagen) is an omnivorous animal, but invertebrates form the basis of its diet.
Activity
Red devil crabs are shy animals, active around the clock, both day and night. They are more active in larger groups, being a herd species.
Interesting Facts
Geosesarma hagen, compared to other similar species, has been found further away from water, indicating good tolerance for lower environmental humidity. In captivity, interbreeding has been observed with the species Geosesarma dennerle. In the wild, both crab species are found in locations only about 10 km apart, suggesting that such interbreeding may also occur naturally, though this phenomenon has not been scientifically described.
Literature
Personal Observations and Experiences
Peter K. L. Ng, Christoph D. Schubart & Christian Lukhaup (2015). New species of “vampire crabs” (Geosesarma De Man, 1892) from central Java, Indonesia, and the identity of Sesarma (Geosesarma) nodulifera De Man, 1892 (Crustacea, Brachyura, Thoracotremata, Sesarmidae). Raffles Bulletin of Zoology.
Yeo, D.C.J. & Ng, P.K.L. (1999). A New Species of Geosesarma (Crustacea: Decapoda: Brachyura: Grapsidae) from Pulau Tioman, Peninsular Malaysia. The Raffles Bulletin of Zoology Supplements (6), 189-196.
Ng, P.K.L. (1986). Preliminary descriptions of 17 new freshwater crabs of the genera Geosesarma, Parathelphusa, Johora and Stoliczia (Crustacea Decapoda, Brachyura) from South East Asia. Journal of the Singapore National Academy of Science. 15: 36–44.
