Common name: Orangutan Crab

General Information

The Orangutan Crab, scientifically known as Achaeus japonicus, is a unique and captivating species that has found its way into the hearts of marine aquarists. Known for its hairy, orangutan-like appearance, this crab is a fascinating addition to any reef aquarium. Its body is covered with fine, hair-like strands that can trap detritus and algae, giving it a camouflaged look that helps it blend into its surroundings.

Despite its unusual appearance, the Orangutan Crab is not just a decorative piece. It plays a significant role in the aquarium by helping to clean up detritus and algae, making it a beneficial addition for those looking to maintain a balanced ecosystem.

Care

Caring for an Orangutan Crab is relatively straightforward, making it suitable for aquarists with moderate experience. They thrive in well-established reef tanks with plenty of live rock, which they use for hiding and foraging. These crabs are not demanding in terms of space, but a tank with a minimum of 50 liters (13 gallons) is recommended to ensure they have enough room to explore and hide.

To keep an Orangutan Crab healthy, maintain stable water conditions with regular water changes and ensure there is enough algae or detritus for them to feed on. They are also known to accept small bits of meaty foods like mysis shrimp, which can be offered occasionally.

Diet and Feeding

Orangutan Crabs are primarily detritivores, feeding on detritus and algae found within the aquarium. Their diet can be supplemented with small meaty foods such as mysis or brine shrimp, especially if the tank is kept particularly clean. Feeding should be done sparingly, as they can usually find enough food on their own in a well-established tank.

Behavior and Compatibility

These crabs are generally peaceful and can coexist with a variety of reef-safe fish and invertebrates. They are not aggressive and spend most of their time camouflaged among the rocks and corals. However, care should be taken when housing them with larger, more aggressive species that might see them as prey.

Orangutan Crabs are reef-safe, but they may occasionally irritate corals by walking over them. Ensure that coral placements allow for some movement without constant interference from the crab.

Symbiosis

While not involved in any specific symbiotic relationships like some other marine species, the Orangutan Crab's ability to blend into its environment can sometimes lead it to form a sort of passive association with certain corals or anemones, using them as cover from predators.

Health and Common Issues

The Orangutan Crab is hardy but can be susceptible to poor water quality and sudden changes in water parameters. Regular monitoring and maintenance of water quality are essential to prevent stress and disease.

When selecting an Orangutan Crab, look for active individuals with intact limbs and a healthy, vibrant appearance. Avoid crabs with missing limbs or those that appear lethargic.

Habitat

The Orangutan Crab is typically found in tropical reef environments throughout the Indo-Pacific region. They inhabit areas with plenty of live rock and coral, where they can easily camouflage and forage for food. Providing a similar environment in captivity will help them thrive.