Zombie Crab – Detailed Guide: Care, Diet, and Facts – petacrab
The zombie crab, an uncommon species to hobbyists – This crab is as interesting as its name. Due to their unpopularity, it is difficult to find information about them; they have some unique characteristics that you may not be aware of.
Image by – inaturalist
They are easy to care for, but you have to keep some things in consideration. Here I’ll talk about everything about the zombie crab, including care, facts and faqs.
| Common names | Black land crab, zombie crab, purple land crab, satanic land crab, zombie land crab |
| Scientific name | Gecarcinus ruricola |
| Care level | Easy |
| Optimal temperature | 73 – 82°F (23 – 28°C) |
| Sleeping nature | Nocturnal |
| Lifespan | 10 years |
| Diet | Omnivore |
| Temperament | Agressive |
From western Cuba, across the Antilles, and as far east as Barbados, zombie crabs can be found and they are considered the most terrestrial of the Caribbean land crabs.
Within the species, there are four color morphs: black, red, yellow, and green. The males have a pointy apron, while the females have more rounded apron
Image source – flickr┃Image by Sue Milks Image source – flickr┃Image by Allan Hopkins mage by – inaturalist
Both males and females reach maturity at around 50 mm of carapace width. The crabs migrate annually for breeding and females lay eggs once a year, from May to July. A female with a 70 mm carapace width can produce about 85,000 eggs.1 The eggs of the zombie crabs hatch in the sea, and the larvae live in the sea. They return to the land when they have developed into the megalops stage before becoming baby crabs.
They make a scratching sound; it is not clear why they do it. Gecarcinus ruricola is a highly territorial species and evolves to fight for that; a hypothesis suggests that they may use a chemical marker to identify their territories (holes).
Gracious ruricola or the zombie crab, has been successfully kept as a pet, and they thrive well in captivity.
Zombie crabs are a great source of protein for the indigenous Taíno in the Caribbean. They catch them, sell them for human consumption or keep them for personal consumption. Basically, the bigger crab species with a lot of meat in the claws are considered edible, like the zombie crabs. So yes, you can eat them.
G. ruricola are called zombie crabs because they avoid light, like they fear sunlight like an actual zombie. The zombie crabs are highly nocturnal; during the day, they avoid sunlight as much as possible to prevent drying out from the hot sun. An experiment demonstrates the effect of dehydration on their food choices.
Researchers offered the crabs lettuce, apple, and herring and deprived them of water for 0, 4, and 8 days. The crabs preferred apple and herring over lettuce and ate less overall as they became more dehydrated. This suggests that with less rain, crabs might eat less, grow slower, and reduce their role in nutrient recycling, impacting coastal ecosystems.
There could be a few other reasons behind their interesting naming –
- Found in graveyards late at night, Barbados locals consider Gecarcinus ruricola to be “satanic.” 2
- A fly called Drosophila carcinophila (an ancient relative to other spotted flies) lives on the zombie crab in the Bahamas and West Indies; this fly lives on the crab and lays eggs in special grooves on the crab’s body without harming it. Baby flies use a special glue to attach themselves to the crab until they grow up.
- Zombie crabs get their eerie name because they’re infected by a parasitic barnacle called Sacculina. This parasite takes over the crab’s body and controls its behavior, much like a puppeteer with a puppet. The crab stops acting like itself and instead, follows the commands of the parasite, making it seem like a zombie. All of the infected crabs are called zombie crabs; it doesn’t refer to G. ruricola. Here you can see –
They can live up to 10 years in their natural habitat. However, they only survive for five years in captivity due to environmental and spatial limitations.
The carapace of a zombie crab can grow up to 5 inches in width; each year, it grows up to 1 inch, reaching maturity after 5 years. With their legs and claws, they can reach more than 8 inches.
Image source – mindenpictures┃Image by Sue Milks Piotr Naskrecki
The main key to caring for gracious ruricola is to create a comfortable habitat that mimics their natural habitat.
They are too big to fit in a small tank; their nature is to walk a lot. To do that, they’ll need a lot of space. 15 to 20 for 1 crab; increase the size to 30 gallons or above for 2-4 crabs.
You should keep males and females in equal ratio or fewer males than females. It will decrease the chance of territorial disputes among males. Cover the tank with a lid, as they can escape easily without one.
The substrate should be able to hold moisture, keeping the exact burrow shape. Take sand, gravel, peat moss and leaf litter and mix them. Here you go, with your perfect substrate. The substrate should be at least 6-8 inches deep.
Make some hiding places with rocks and wood, place some climbing medium, and then decorate accordingly.
Keep the temperature between 73 and 82°F. Zombie crabs are pretty hardy crustaceans that adapt to life at different temperatures. A little jump in temperature won’t cause any problems. The humidity should be between 70% and 90%; don’t forget to use related equipment such as a hygrometer, humidifier, and thermometer.
Place two bowls of water, one for saltwater and the other for freshwater. Prepare the saltwater with reef salt and ensure the water doesn’t contain chlorine. Adjust the light, resembling the cycle of day and night in nature.
Zombie crabs are omnivorous scavengers; their brothers from the same genus, Gecarcinus lateralis have a herbivorous food preference. They also have the same preference, meaning most of their diet contains plant matter.
Give them flakes, pellets, fruits, vegetables, brine shrimp, small fish, and worms.