Red Devil Vampire Crabs are

decapod The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfish, shrimp, and p ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s part of Brachyura (from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''βραχύς'' = short, ''οὐρά'' = tail/abdomen). They are land living, freshwater crabs from tropical areas and are endemic to Indonesia. Like all other crabs, they have a carapace, two

chelae A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds ...

and ten jointed legs. They are omnivorous. The species is named after the

Rolf C. Hagen Group Hagen Inc. (officially The Rolf C. Hagen Group of Companies) is a pet supplies company headquartered in Montreal, Quebec, Canada, and founded in 1955 by Rolf C. Hagen with the help of his brothers, Dieter and Horst. Dieter and Horst Hagen joine ...

, which supported work by Christian Lukhaup and Christoph D. Schubart, two of the authors of the describing article. ''G. hagen'' is often found in the

aquarium trade Fishkeeping is a popular hobby, practiced by aquarists, concerned with keeping fish in a home aquarium or garden pond. It is a practice that encompasses the art of maintaining one's own aquatic ecosystem, featuring a lot of variety with various ...

and it is relatively inexpensive. The common name was given as a marketing move in order to attract more attention to the crab from buyers and keepers. This is a shared characteristic of all ''Geosesarma'' crabs.

Environment

''Geosesarma hagen'' is a species of small land-living

crab Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...

s only found in

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. The crabs prefer a humid environment with elements from both terrestrial and freshwater aquatic habitats. They steer clear of drier land and although the younger crabs tend to live in closer proximity to the water, they are not aquatic crabs. Young Red Devil crabs spend most of their time in the water as a way to avoid predators. They are used to living in warm humid conditions and their preferred temperature ranges from 24-28 degrees Celsius (75-82 F). There are many species of ''Geosesarma'' crabs living in the same natural habitat in Java, and they can all be easily identified by their bright and unusual colors. They are all known as vampire crabs.

Morphology

They can reach up to 7 cm (3 in) in length counting the full leg span. Amongst their distinguishing features, ''G. hagen'' has a wider, square shape body, dark brown anterior

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

and legs, while the posterior of the carapace and the claws/

are instead orange/red. Their

abdomen The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...

is usually gray and they have bright yellow eyes.

Reproduction and Life Cycle

''G. hagen'' can live up to 2 years, but they average about 1.5 years. They undergo molting in order to grow and recover lost legs and limbs within a few months of losing them. They can go through several molts during their lifetime. The Red Devil Vampire crabs are

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

and males have a narrow and slimmer plate while females have a broad plate on their belly and they might also be carrying around some fertilized eggs. Another difference between male and female crabs is in their claws: males have larger and brighter claws while females have smaller claws. Mating occurs when the female is ready to mate and it lasts for several minutes. The females release their eggs in freshwater and each female can carry about 12-24 eggs. Incubation lasts around 30–50 days and the larval stage is completely absent. The hatched crab develops directly and they lack coloration when they are young (they become dark brown and then eventually develop bright adult coloration).

Behavior

Red Devil Crabs are

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

and spend most of their life hidden from the light in order to avoid predation. At night, they become active hunters and scavengers. They will engage in fights over territory, especially between males. They should be housed with plenty of space, even individually, unless breeding is desired. Like with many crabs, ''G. hagen'' shows higher social and behavioral complexity than most invertebrates. They are however often aggressive with crabs of other species, including other ''Geosesarma'' species. They often create their shelters by digging up small amounts of dirt near bodies of water. Though they are not generally thought of as true burrowers, they spend most of their time hidden in these dens.

Ecology

The Red Devils are

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s (though they show a preference for carnivorous prey), and their diet ranges from small detritus and dead plants to fruit flies, woodlice and other bugs. They also are key animals in the microbial loop in the tropics as well as key players for biogeochemical nutrient cycling. (Lidquist et al. 2009)

Relationship with Humans

It is popular in the aquarium trade, where it is sometimes called "Geosesarma red devil"Archived a
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and th
Wayback Machine
or "''Geosesarma'' sp "rot" (''rot'' means "red" in German). All species of ''

Geosesarma ''Geosesarma'' is genus of small freshwater crab, freshwater or terrestrial crabs, typically less than across the carapace. They live and reproduce on land with the crustacean larvae, larval stages inside the egg (biology), egg. They are found f ...

'' crabs are often called "vampire crabs" in the aquarium trade. The crabs are not known to pose any danger to humans, though their bright coloration may suggest otherwise at a first glance.

References

3. Michael. (2022, February 18). ''Red Devil Crab – Detailed Guide: Care, Diet, and breeding''. Shrimp and Snail Breeder. Retrieved April 7, 2022, from https://aquariumbreeder.com/red-devil-crab-detailed-guide-care/ 4. Freitag, H., Manuel-Santos, M., & Ng, P. K. L. (1892). ''Two new species of Geosesarma de Man, 1892 (crustacea: Brachyura: Sesarmidae) from Palawan, the Philippines''. Archīum Ateneo. Retrieved April 12, 2022, from https://archium.ateneo.edu/biology-faculty-pubs/8/ 5. Lindquist, E. S., et al. (2009). ''Land Crabs as key drivers in ... - Wiley Online Library''. Retrieved from https://onlinelibrary.wiley.com/doi/full/10.1111/j.1469-185X.2008.00070.x 6. Burggren, W., & McMahon, B. R. (2009). ''Biology of the land crabs''. Cambridge University Press. 7. Ng, Peter K. L.; Wowor, Daisy (2019). ''The vampire crabs of Java, with descriptions of five new species from Mount Halimun Salak National Park, West Java, Indonesia (Crustacea: Brachyura: Sesarmidae: Geosesarma).'' https://web.p.ebscohost.com/abstract?site=ehost&scope=site&jrnl=02172445&AN=140243800&h=IzfZIqXBjIe1tn4LM%2brOJNoz6ywTBYFug362mxESHsvblTfmmb4aYlSch3cnPIAPL9gEJ692HYuqQ%2bOwJqCdvQ%3d%3d&crl=c&resultLocal=ErrCrlNoResults&resultNs=Ehost&crlhashurl=login.aspx%3fdirect%3dtrue%26profile%3dehost%26scope%3dsite%26authtype%3dcrawler%26jrnl%3d02172445%26AN%3d140243800 8. Yeo, D. C. J., Ng, P. K. L., Cumberlidge, N., Magalhães, C., Daniels, S. R., & Campos, M. R. (1970, January 1). ''Global diversity of crabs (crustacea: Decapoda: Brachyura) in freshwater''. SpringerLink. Retrieved April 25, 2022, from https://link.springer.com/chapter/10.1007/978-1-4020-8259-7_30

External links

*
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)Geosesarma crabs mating
- Video of G. hagen crabs mating * {{Taxonbar, from=Q19346023 Grapsoidea Freshwater crustaceans of Asia Crustaceans described in 2015 Taxa named by Peter Kee Lin Ng