Purple Vampire Crab (Geosesarma dennerle)

Purple Vampire Crab is the familiar aquarium-trade name used for this vivid, semi-terrestrial Geosesarma crab. Our supplier lists it as Geosesarma dennerle, the accepted name used on this product, but responsible identification matters: several different-looking Geosesarma have been sold under the same name in the international trade. This listing therefore separates what is documented from what is practical keeper guidance. It does not promise a locality, captive-bred status, sex, exact colour pattern or exact adult measurement that our supplier has not verified.

This is one unsexed crab per quantity selected. It is not a pair and it is not a fully aquatic community-tank crab. Prepare a secure, planted paludarium with much more usable land than water, shallow conditioned freshwater, numerous retreats and easy routes out of the water before dispatch. The first gallery image is the real source photograph available for this line. The four following images are clearly described as illustrative, habitat views; they help with enclosure planning but are not photographs of the exact animal that will arrive.

Purple Vampire Crab at a Glance

Ranges on care sheets should be treated as operating guidance, not as proof of the conditions at every wild collection point. For this product we favour a stable target near the centre of the published husbandry ranges: approximately 22-26°C, high humidity with active ventilation, and clean freshwater that is neither extremely soft nor allowed to accumulate waste. A mature enclosure with several microclimates is more forgiving than a small sealed box held at one exact number.

Identity, Trade Names and Why Caution Matters

Geosesarma dennerle was formally described in 2015 from Central Java. The original description records a striking but variable adult pattern: violet-purple to purplish-brown areas on the front of the carapace and walking legs, a pale cream or yellow area towards the rear, bright purple claws and yellow eyes. Juveniles can be much paler, and even adults do not all show an identical distribution of colour. Lighting, background, stress, recent moulting, age and camera processing can change how those colours appear in a photograph.

A 2024 morphological and molecular study traced confirmed material from the Cilacap area of Central Java and also examined animals from the ornamental trade. It found useful agreement for some specimens, but modern trade research has shown why a product page should not claim more than its evidence supports. A 2026 systematic survey found that sellers frequently attached the name G. dennerle to multiple phenotypes, some of which aligned more closely with other species. Common names, copied care text and stock photographs can amplify that uncertainty.

This distinction is useful rather than evasive. The enclosure advice remains appropriate for a small, land-associated vampire crab, while the customer is not encouraged to treat a colour label as a genetic certificate. It also prevents the common mistake of assuming that every purple-and-yellow crab in a mixed trade shipment must be visually identical to a photographed type specimen.

What You Receive

Each unit ordered is one live, unsexed Purple Vampire Crab supplied under the name Geosesarma dennerle. Sex is not a selectable option on this product. We do not promise a male, female, pair or breeding group. If you order more than one, that increases the quantity of individual crabs; it does not guarantee a sex ratio or guarantee that all individuals will live together without territorial management.

The supplier lists a size of 4 cm but does not state whether this is carapace width, total body length or leg span. Those measurements are not interchangeable. Published scientific specimens are measured by carapace dimensions and are much smaller than an outstretched leg-span measurement. We therefore preserve the supplier's 4 cm listing as provenance, but do not present it as a scientifically verified adult carapace size or a guarantee for every dispatched animal.

Colour and pattern vary naturally. A newly moulted, juvenile, resting or transport-stressed crab can look lighter or less saturated than an established animal photographed under display lighting. Missing or regenerating limb tips can also occur in decapod crustaceans. Contact us promptly with clear photographs if the animal arrives in a condition that concerns you, and follow the evidence and timing requirements in our Live Arrival Guarantee.

How to Read the Gallery

The first image is the real source photograph available for this supplied line. It shows a small crab on a green leaf with yellow eyes, violet-purple claws and a dark, patterned carapace. It is the most useful image for checking the trade appearance, but it is still a reference image rather than a portrait of the exact individual allocated to an order.

The remaining four gallery images are illustrative, scenes. They show the crab among wood and planting, a two-crab scene, a side view on a plain background and an example with nearby plants. They are retained because they make the page more visual and can help a keeper think about cover, access and scale. They must not be read as evidence that two crabs are included, that the pictured sex is selectable, that every animal has identical markings or that a particular plant arrangement is sufficient husbandry.

Natural image descriptions help both customers and image search understand what each frame actually contains. For that reason, our gallery text describes visible features and labels illustrative images honestly; it does not repeat a stock code or force shopping phrases into every alt attribute.

Natural History and Documented Habitat

The strongest field evidence places confirmed G. dennerle in Central Java. The 2024 study reports animals in a landscape with dense shrubs, small flowing watercourses, plant litter and burrows in creek banks. Adults were found around terrestrial retreats and were observed entering water on occasion, while younger animals occurred nearer the river margin. This is a much more informative model than calling the species either an aquarium crab or a dry-land terrarium animal.

In a home enclosure, translate that habitat into connected zones: humid land with litter and crevices, protected routes between hides, and freshwater that can be entered and left without a steep glass trap. The aim is not to reproduce a Central Javan site decoratively. It is to provide the functions documented there: moist shelter, structural complexity, access to water, foraging surfaces and a choice of microclimates.

Field observations do not justify claiming that every traded crab was collected at the type locality. Supplier origin and captive-bred status are not provided for this line. We therefore do not describe these animals as captive-bred or wild-caught without evidence. That provenance gap is common in the online land-crab trade and is one reason the scientific sources are linked in the methodology section below.

Building a Land-Led Paludarium

There is no single scientifically proven litre minimum for this product. Volume can be misleading because a tall aquarium may hold many litres while providing little usable floor area. As practical retail guidance, start around a 60 x 30 cm footprint for one crab or a carefully managed small same-type group, then increase floor area, retreats and feeding stations as numbers rise. A larger enclosure is easier to zone and often more stable.

A land share of roughly 70-80% is a useful starting design, not a law of nature. The land must be genuinely usable: firm enough to walk and burrow against, damp below the surface without becoming waterlogged, and connected by wood, stones or gentle slopes. A false bottom or drainage layer can stop the terrestrial substrate from sitting permanently in dirty water, but it must not create inaccessible gaps where a crab can become trapped.

Keep the freshwater section shallow enough to manage and deep enough for the crab to submerge if it chooses. Depth matters less than safe access. Use textured ramps, cork, roots or stone so an animal can leave from more than one point. Avoid a single slippery vertical bank. Shield filter intakes and make sure décor cannot shift when a crab digs beneath it.

Secure every cable opening, lid corner and ventilation gap. Vampire crabs climb silicone seams, plants, textured backgrounds and pipework. A gap that looks too small from above may become accessible from a branch. Use a close-fitting lid and fine, rust-resistant ventilation mesh. Check the enclosure after maintenance because moved cables and slightly raised lids are common escape routes.

Temperature, Humidity and Ventilation

For captive care, a stable 22-26°C is a sensible working target. Some general vampire-crab care sheets publish wider ranges, but a broad tolerance should not become an excuse for daily swings. Measure where the crab lives, not only at the top of the enclosure. Water, damp substrate, exposed branches and the air beneath the lid may all differ.

Use a thermostatically controlled heat source appropriate to the enclosure. In many UK homes, winter room temperature makes supplemental heat necessary. Protect the animal from direct contact with hot equipment and avoid creating one heated, desiccating wall. A gentle gradient lets the crab choose. Do not place a small sealed paludarium in direct sun; glass can warm very quickly even when the room feels cool.

A practical humidity target begins around 75%, with damp refuges always available. Humidity is not the same as stagnant, saturated air. Constant condensation, mould, sour substrate and a musty smell indicate that the balance is wrong. Combine moisture-retentive substrate and planting with cross-ventilation. Hygrometers are useful for trends, but inexpensive sensors can differ; confirm the enclosure by observing substrate condition, condensation and animal behaviour rather than chasing a single digital reading.

Freshwater Quality, Filtration and Safe Access

The water section may be smaller than the land section, but it still needs mature biological filtration or an equally reliable maintenance plan. Condition tap water appropriately and cycle the aquatic section before the crab arrives. Test for ammonia and nitrite; both should remain at zero on a normal hobby test. Keep nitrate controlled through sensible feeding, plant growth and partial water changes.

Published care guidance commonly places vampire crabs in neutral to mildly alkaline freshwater with moderate mineral content. A broad practical range around pH 7.0-8.0 can work when it is stable. General care sheets also cite approximately 4-16 dGH. Those numbers are guides, not a reason to make abrupt chemical corrections. Learn the local water first. If remineralisation is needed, change it gradually and measure consistently.

Choose gentle filtration. A small air-driven sponge filter is easy to shield and supports biofilm, while a carefully baffled internal filter can also work. Strong flow is unnecessary. Any intake must be inaccessible to a small crab, and electrical equipment must be rated for its use. Provide several rough exits even if the water is shallow; a weak or freshly moulted animal should not have to climb one polished wall.

Remove decaying food before it disappears under wood or into saturated substrate. Change a modest portion of the water when testing and observation show it is needed, matching temperature and avoiding abrupt chemistry shifts. Never clean all filter media and all substrate on the same day. Preserve the mature microbial surfaces that keep a small water volume stable.

Substrate, Plants and Hardscape

A useful terrestrial substrate holds moisture, allows shallow digging and remains structurally open. A mix based on suitable soil or coir with bark, leaf litter and mineral material can work, provided no component contains pesticides, fertiliser granules, perfume or unsuitable wetting agents. Leaf litter is not merely visual: it provides cover, grazing surfaces and a gradual source of decomposing organic material.

Use hardwood leaves and botanicals known to be safe in invertebrate enclosures. Replace them in layers so part of the litter remains mature. Sterilise or quarantine collected materials appropriately and avoid roadsides or treated gardens. Powdery mould on a new leaf can be part of decomposition, but rapid spreading growth, sour smells and soaked anaerobic substrate require better airflow, less food or removal of the affected material.

Plants help stabilise humidity and break sightlines. Mosses, small ferns, creeping tropical plants, emersed Anubias and other humidity-tolerant species are commonly used, but every plant must be free from harmful pesticide residues. Rinse and quarantine new plants where practical. Browse our aquarium plants for aquatic and emersed possibilities, then check whether each species suits the land or water zone you intend to build.

Hardscape must be stable before substrate is added around it. Crabs investigate gaps and may excavate beneath light objects. Support heavy stone from the enclosure base rather than balancing it on loose soil. Cork bark and branching wood create excellent shaded routes, but leave enough access for inspection. A visually dramatic structure that cannot be checked, cleaned or dismantled safely is not a practical home.

Feeding a Varied Omnivore Diet

Field work and general Geosesarma biology support an omnivorous, opportunistic diet associated with insects, plant material, litter and small food items found around humid margins. In captivity, use variety rather than trying to identify one perfect food. A quality crustacean or invertebrate pellet can provide a measured staple, rotated with small animal-protein foods, vegetable material and naturally grazed surfaces.

Suitable protein options can include appropriately sized frozen or dried invertebrate foods, small pieces of unseasoned seafood or cultured feeder insects from a safe source. Plant-based rotation can include a little blanched courgette, leafy vegetable or pumpkin. Portions should be tiny relative to what a fish keeper might offer. Remove soft leftovers before they sour, attract mites or pollute the water.

Provide calcium and other minerals through a balanced diet and a suitable crustacean-safe mineral source. Cuttlebone or a formulated invertebrate mineral food can be useful, but adding large quantities is not a substitute for testing water and managing diet. Do not dust every meal heavily or make unmeasured changes to water chemistry.

Feed when you can observe the response, often towards evening, and distribute food near more than one retreat if multiple crabs are present. A shy animal may not cross a dominant individual's territory. There is no universal daily portion because animal size, temperature, enclosure maturity and food density differ. Use body condition, activity and leftovers to adjust gradually.

Social Behaviour and Group Planning

Vampire crabs are often described as social because they can occur and reproduce in groups, but that should not be confused with schooling or guaranteed peaceful coexistence. Individuals use retreats and can defend access to food, cover and space. A group that appears calm in a highly structured enclosure may behave very differently after a major clean removes boundaries.

There is no guaranteed formula of one male to a fixed number of females for this product, especially when sex is not selected. If keeping more than one, provide more retreats than crabs, multiple feeding points and broken sightlines on both land and at the water edge. Increase usable footprint before increasing numbers. Watch for repeated chasing, limb damage, an animal permanently excluded from food, or one individual remaining high in a corner with no secure route down.

Be prepared to separate animals. A spare secure, heated and humid enclosure is more useful than hoping aggression resolves itself. Never introduce a new crab directly into the only prime hide. Rearranging part of the territory, adding cover and offering food at several points can reduce immediate competition, but it does not guarantee compatibility.

Mixing differently labelled vampire crabs creates further problems. Similar care needs do not prove they are the same species, and trade identifications can be uncertain. Mixed animals may compete, injure one another or potentially compromise a breeding line. A species-focused enclosure is the clearest default.

Compatibility with Fish, Shrimp and Other Crabs

This crab is best planned as the principal animal in a land-led paludarium. A normal fish community requires much more open water, while the crab requires extensive humid land. Building for both can leave neither animal with an appropriate environment. Small fish or shrimp in the water section may also be caught, injured or stressed, and the crab itself may be vulnerable during a moult.

Snails and microfauna are not guaranteed companions. Some keepers use springtails or appropriate clean-up organisms in the land section, but each addition needs its own husbandry assessment and may still be eaten. Avoid assuming that a small animal is safe because it is too quick or too hard-shelled. Observe and have a removal plan.

Do not mix this product with brackish red-claw crabs, fiddler crabs, large predatory crabs or fully aquatic species simply because all are sold as crabs. Their salinity, territory, water depth and social requirements can be very different. The parent crab category is useful for comparing available types, while the dedicated vampire crab category keeps land-associated options together.

Arrival and Acclimation

Read the dispatch message and have the paludarium ready before opening the parcel. Inspect the package promptly in good light and follow the enclosed or emailed arrival instructions. Take clear photographs before altering the packaging if there is a concern relevant to the Live Arrival Guarantee. Do not leave the parcel beside a radiator, in direct sun or in a cold vehicle.

Transport can temporarily change posture, activity and colour. Give the crab a quiet, secure transfer route into a prepared retreat rather than placing it in an open display area for photographs. Do not lift it by a leg or claw. If a container must be moved, guide the crab gently using the container and a soft barrier, keeping escape routes closed.

Match temperature gradually and avoid pouring shipping water into the enclosure. Because this is a semi-terrestrial animal, generic fish-bag drip acclimation may not be the most suitable instruction in every case. Follow the livestock directions supplied with the order and prioritise warm humid air, access to conditioned freshwater and immediate shelter.

For the first days, keep disturbance low, maintain the usual light cycle and offer a very small amount of food near cover. Hiding is expected. Confirm welfare by looking for moved food, fresh tracks in damp substrate and changes in retreat use rather than repeatedly lifting hides. If the animal remains exposed, unresponsive or unable to grip, document the condition and contact us.

Moulting and Mineral Support

Like other crabs, a Purple Vampire Crab grows by shedding its exoskeleton. Before a moult it may eat less, hide more and become difficult to see. The new shell is soft immediately afterwards, making privacy and freedom from harassment especially important. Do not excavate a missing crab simply because it has not appeared for several days.

Provide stable moisture, clean water, a varied diet and mineral support before a moult is due; these are ongoing conditions, not an emergency treatment. Avoid abrupt changes to hardness or humidity. If multiple crabs are housed together, retreats must allow a soft animal to remain completely out of sight and away from feeding competition.

An intact shed exoskeleton can look like a dead crab. Check for a split along the shell and an empty, translucent interior before reacting. It is often useful to leave the moult in place because the crab may consume minerals from it. Remove it only if it is clearly fouling the enclosure or remains untouched and mouldy.

Health Checks and Troubleshooting

Observe movement, grip, posture, feeding response, shell condition and use of land and water. A settled crab should be able to move deliberately and right itself. Colour alone is not a reliable health test because lighting, age and moult stage change appearance. Persistent inability to grip, a strong odour, active tissue damage, repeated failed moults or prolonged exposure without normal sheltering deserve prompt attention.

Start troubleshooting with the environment. Check actual temperatures in several zones, humidity trend, ventilation, ammonia, nitrite, nitrate, pH stability, water access, escape security and recent cleaning or décor changes. Look for uneaten food, a blocked filter, collapsed hide or a dominant tank mate. Correct one evidenced problem at a time so the response can be understood.

Do not dose a paludarium with a generic fish medication because a symptom resembles a fish disease. Many medicines have not been evaluated for small terrestrial crabs, and copper-containing or other invertebrate-unsafe products may be harmful. Seek advice from an exotics veterinarian or an experienced invertebrate professional, provide the product label and describe both the land and water conditions.

Routine handling is unnecessary and can result in falls, dropped limbs or escape. If isolation is required, the temporary enclosure must still provide controlled warmth, humid shelter, ventilation and safe freshwater access. A dry ventilated box or a deep bare container is not a suitable hospital environment.

Sexing, Breeding and Evidence Limits

Mature true crabs are commonly sexed by examining the shape of the abdominal apron on the underside: females generally have a broader, rounded apron, while males have a narrower form. Reliable sexing requires a clear view and sufficient maturity. Colour intensity, claw colour and apparent body size are not dependable substitutes. This listing remains unsexed because no sex option is verified at fulfilment.

Most Geosesarma species for which egg information is known have large eggs and direct or strongly abbreviated development. In direct development, young emerge as small crab-shaped juveniles rather than passing through the familiar free-swimming marine larval sequence. That is a useful genus-level biological context, but it does not justify promising that every supplied animal is mature, paired or ready to breed.

We do not repeat the widely copied claims of exactly 20-80 eggs or an exact one-month carrying period as guaranteed facts for this stock. Brood observations vary among species and sources, while trade identity is not always secure. A breeding project needs a stable mature enclosure, secure species identification, suitable adults, dense juvenile refuge and a plan for separating size classes if predation occurs.

If a female carries eggs or young, minimise disturbance. Maintain ordinary stable conditions rather than making a sudden humidity or feeding change. Tiny juveniles need mature microhabitat, fine foods, safe water edges and far more crevices than their size suggests. Adult presence and sibling size differences can create losses, so breeding is not a hands-off consequence of keeping several crabs together.

A Practical Maintenance Rhythm

A paludarium should not be stripped clean on a calendar. Spot-clean feeding areas, preserve mature litter and biofilm, and service aquatic equipment without removing all biological media at once. Larger corrective work is justified when there is contamination, structural failure or a measured water-quality problem, not simply because natural materials look earthy.

Keep replacement water, dechlorinator, test kits and a spare secure container available. Check the thermostat and sensors periodically against another instrument. Replace worn lid clips and mesh before they fail. Prevention is especially important with a climbing animal that can exploit a maintenance mistake within minutes.

How This Crab Differs from Other Aquarium Crabs

The name "freshwater crab" covers animals with very different lives. Purple Vampire Crabs are selected for a humid, land-led display and close observation, not for cleaning an aquarium. A Thai micro crab is tiny and fully aquatic; a red-claw crab is larger and commonly associated with brackish, shoreline-style care; many fiddler crabs also need a very different land-water and salinity plan. Similar product names do not make their enclosures interchangeable.

Choose this product when the attraction is the relationship between the animal and a planted habitat: emerging from leaves, using low burrows, crossing wood and visiting shallow water. Choose a different crab when the objective is a fully aquatic community display. Making that decision before purchase protects both the animal and the rest of the collection.

Pre-Order Planning Checklist

Sources and Method

This page distinguishes primary biological evidence, current trade evidence, supplier data and practical captive-care guidance. That matters because online vampire-crab pages often repeat one another until an unsupported number looks authoritative. We have retained uncertainty where the evidence cannot identify the exact dispatched animal.

• Ng, Schubart and Lukhaup (2015), formal description of Geosesarma dennerle: taxonomy, documented colour variation and type-locality context.
• Mahendra and colleagues (2024), morphological and molecular tracing: Central Java sampling, observed creek-bank habitat, measurements of examined specimens and trade comparison.
• Systematic survey of land crabs in the online aquarium trade (2026): evidence of inconsistent names, photographs and provenance in listings, including G. dennerle.
• Shy and Ng (2019), Geosesarma reproductive biology context: large eggs and direct development are widespread in the genus, with important species-level exceptions.
• Current specialist vampire-crab care guide: practical captive ranges for temperature, humidity and freshwater management, treated here as broad husbandry guidance rather than locality data.

The supplier record provides the accepted sale name, one product line and a listed 4 cm size, but it does not define the measurement method or verify sex, locality, lifespan, brood size or captive-bred status. Our recommendations on enclosure footprint, land-water zoning, food rotation and maintenance are conservative keeper guidance assembled around the animal's documented semi-terrestrial ecology. They should be adjusted to observed welfare and measured enclosure conditions.

Why Order from Tropical Fish Co?

A useful livestock listing should help you decide against an unsuitable purchase as confidently as it helps you proceed with the right one. Here you can see the supplier identity, the real source photograph, the status of illustrative images, the unsexed one-crab sale unit, the trade-identification limitation and the complete paludarium planning requirements before checkout.

We support eligible livestock orders with our Live Arrival Guarantee when its conditions are followed, and publish current dispatch information so the animal's arrival can be planned around a ready enclosure. The price and stock shown by the buy box are the current Shopify values; this care text does not hard-code availability or invent a promotional price. First-time eligible customers can use WELCOME10 for 10% off under the current offer terms.

For more planning help, read the delivery page, review the Live Arrival Guarantee and use the site-wide frequently asked questions. Those pages hold the current operational terms, while this product page stays focused on the animal, its evidence and the enclosure it needs.

Continue Your Research

Compare this listing with the live vampire crab selection and the wider crab collection. When planning the planted zones, browse aquarium plants and verify that each choice is suitable for emersed or submerged use in your design. Complete the habitat first, let the freshwater section mature, then choose the dispatch date.