Vampire crabs ( Geosesarma dennerle) have rapidly gained popularity in the ornamental pet trade due to their striking appearance and relatively simple care requirements. These semi-terrestrial creatures, first introduced in 2006, belong to the genus Geosesarma, which encompasses a diverse group of crabs found across Southeast Asia, the eastern Indian Ocean, and the western Pacific. Despite their rising popularity, the ecology and biology of Geosesarma species, including vampire crabs, remain poorly understood. This comprehensive guide aims to provide valuable insights into the dietary needs and feeding habits of vampire crabs, ensuring their health and well-being in captivity.
Understanding Vampire Crabs
Vampire crabs are named for their glowing yellow eyes and creamy spots on their backs, which some say resemble a bat-like shape. However, others suggest the name is simply a clever marketing tactic. These small crabs barely reach 5 cm (2 inches) across the leg span, with a carapace (shell width) of about 2.5 cm (~1 inch) wide. They are nocturnal and somewhat shy, preferring to spend their days hiding among dense vegetation, rocks, or leaf litter.
Like other crustaceans, vampire crabs possess a hard exoskeleton that protects their internal organs. This rigid shell prevents growth, necessitating molting. During molting, vampire crabs shed their old exoskeletons to allow for growth. They are most vulnerable during and immediately after this process.
Habitat and Housing
Vampire crabs are semi-terrestrial animals, requiring more land than water in their enclosure. A paludarium, which combines both land and water features, is the ideal setup. An 80/20 or at least 50/50 land-to-water ratio is recommended. They need water deep enough to submerge themselves for molting and breeding, but they cannot stay submerged for extended periods as they will drown. Clean water is crucial, and regular water changes or a filter system are necessary to maintain water quality.
In their natural habitat, vampire crabs live in leaf litter and rotten wood near streams. Therefore, their enclosure should include plenty of hiding places such as leaves, rocks, wood, plants, and PVC pipes. Live plants are a great addition, as vampire crabs do not typically eat healthy plants. The ideal water pH is between 7.5 and 8.0, and stable humidity levels of 75% or higher are essential.
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General Feeding Habits
Vampire crabs are predominantly omnivorous scavengers, consuming both plant and animal matter. In their natural environment, they feed on insects, small fish, decaying organic material, and algae. This adaptable diet makes feeding them in captivity relatively straightforward.
They graze throughout the day and night on microfauna in their environment. Therefore, it is super important to set up a bioactive ecosystem for them. This gives them a plentiful source of food to eat while they roam around the tank, such as springtails, aquatic snails, isopods earthworms, moss, and other decaying elements in their range. While this is super convenient making them fairly easy to care for, you also need to substitute their diet with extra nutrients.
Dietary Requirements
A varied diet is key to maintaining the health and vibrancy of vampire crabs. A combination of live, frozen, and commercially prepared foods is ideal.
Live and Frozen Foods
These provide essential nutrients and mimic the crabs' natural diet:
- Brine shrimp: A readily available and nutritious option.
- Bloodworms: A good source of protein.
- Earthworms: Provide essential nutrients.
- Crickets: Offer a crunchy texture and protein.
- Frozen fish: Another good option for protein
Commercial Foods
Flake food, algae wafers, and pellets can supplement the diet, but should not be the sole food source. Choose high-quality options formulated for omnivorous fish or invertebrates.
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Fresh Foods
Small pieces of fresh or boiled vegetables, such as broccoli and zucchini, can provide essential vitamins and minerals. Include a variety of leafy greens and other vegetables to ensure a balanced diet.
Calcium
Calcium is crucial for the development of a healthy, strong exoskeleton. Supplement the crabs' diet with calcium-rich foods or a calcium supplement.
- Leafy greens: Such as kale and spinach, are good sources of calcium.
- Cuttlebone: A natural source of calcium that can be placed in the enclosure.
- Calcium supplements: Available in powder or liquid form, can be added to the crabs' food or water.
Bioactive Setups
A bioactive setup with isopods and springtails provides a constant source of microfauna for the crabs to graze on. Leaf litter and decaying wood also support the growth of beneficial microorganisms that the crabs can consume.
Feeding Schedule
Vampire crabs should be fed once a day, preferably in the evening or after lights out, as they are primarily nocturnal. Offer a small amount of food that the crabs can consume within a few hours. Remove any uneaten food to prevent it from spoiling and fouling the water.
Depending on your crabs you can usually get away with feeding them about 3 times a week. The most important thing is that you feed them something different on each of the days you feed them. I generally feed my crabs on Monday, Wednesday, and Friday to keep things simple. One day I feed some kind of store-bought fish food, either a flake or granule type food. The next time I feed some boiled vegetables such as broccoli or zucchini, and on the third day I will feed something meaty, like frozen fish, blood worms, frozen crickets, etc. Then as the weeks roll on I will continue that method rotating through food types.
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Special Considerations
Molting
During molting, vampire crabs are particularly vulnerable and may not eat for a few days. Ensure they have access to plenty of hiding places and maintain optimal water quality to support the molting process.
Breeding
Breeding crabs require a diet rich in protein and calcium to support egg production and the development of healthy offspring. Increase the frequency and quantity of protein-rich foods, such as live insects and frozen foods, and supplement with calcium as needed.
Vacation Feeding
If you are going away for a short period (up to 3 weeks), vampire crabs can typically survive by scavenging for food in their environment. Before leaving, feed them well and add extra live foods, such as isopods, crickets, or worms, to the enclosure. A small leaf of raw cabbage or lettuce can also provide a long-lasting food source. Extra isopods, crickets, worms etc. I also put a small leaf of raw cabbage or lettuce into the tank. Both of these are highly resistant to mold and the crabs will pick at it over time.
Mold Prevention
Mold can be a problem in humid enclosures. Remove any uneaten food promptly and ensure good ventilation to prevent mold growth. Springtails can also help control mold by feeding on it.
Social Behavior and Tank Mates
Vampire crabs are social animals that generally do well in groups of their own kind. However, they can be territorial, especially males. Provide plenty of space and hiding places to minimize aggression. It is important to house an appropriate sex ratio and avoid housing too many males in a small enclosure, as they can kill each other. The typical recommendation is to keep 1 male to every 3 females.
They may prey on small fish, shrimp, and other crabs. If keeping vampire crabs with fish, choose larger, non-aggressive species that are unlikely to become prey. Large snails can be a safe option, as they typically do not bother the crabs.