Christmas Island Red Crab: Christmas Island National Park Treasure

Christmas Island Red Crab Christmas Island National Park Treasure

Just envision this: a crimson army of 100 million crustaceans, their pincers held high like defiant flags, scuttling across the lush greenery of Christmas Island; this’s not the scene of any novel; it’s the annual migration of the Christmas Island red crab.

We welcome you to the bewitching realm of Christmas Island, where nature reveals its most enormous show with the mesmerizing Christmas Island red crab – a creature that’s as vibrant as its namesake island. So, what you’re waiting for? Join us on this journey and witness the wonder of the Christmas Island red crab’s migration for yourself!

KingdomPhylumClassOrderFamilyGenusScientific Name
AnimaliaMolluscaCephalopodaOctopodaEnteroctopodidaeEnteroctopusEnteroctopus dofleini
Taxonomic Classification of Giant Pacific Octopus (Enteroctopus dofleini)

Origin and Evolution

Evolutionary History

Curious to know Christmas Island red crab’s lineage? You can trace it back to the Jurassic period, over 150 million years ago, when red land crabs were abundant. As temporal waves flow, the species diverged from its mainland relatives to the unparalleled environment of Christmas Island – a volcanic outcrop in the Indian Ocean.

Genetic Composition and Diversity

As per a research made public in the journal “Conservation Genetics,” it’s found that the Christmas Island red crab’s population harbors a moderate degree of genetic diversity having a projected 150 polymorphic microsatellite markers. This diversity is likely associated with the species’ long evolutionary history.  

Environmental Adaptations

To its rainforest environment, the red land crab has evolved outstanding adaptations. Its vigorous body, blessed with powerful claws and legs, let it traverse the rugged terrain of the island. It’s its carapace – a hard exoskeleton – that guards it from predators and the harsh elements. In addition, studies have unfolded that the creature features thermal tolerance, able to survive in temperatures stretching from 10 to 40 degrees Celsius (50 to 104 degrees Fahrenheit).

Distribution and Population

Christmas Island Red Crab Distribution and Population

Geographic Range

The red land crab, also known as robber crab, inhabit Christmas Island – a small island located around 2,600 kilometers (1,600 miles) northwest of Australia. The rainforest of this island offers it with the ultimate habitat for its survival and reproduction.

Population Dynamics

Recent studies propose that the Christmas Island red crab’s population may be declining due to invasive species, habitat destruction and climate change. A survey conducted in 2021estimated the total population of red island crab to be approximately 40 million – a substantial shrinkage from prior estimates of over 100 million.


Continent(s) Australia (Christmas Island is an Australian territory)
Countries Australia
Bio-geographical RealmsOceanian Realm, Australasian
Biome Tropical and subtropical moist broadleaf forests
Climate ZonesTropical monsoon


Christmas Island Red Crab habitat

Habitat Preferences

When it comes to the Christmas Island red crab’s habitat, the moist, humid environment of the island’s rainforests is what it prefers. To escape predators and regulate its body temperature, it spends most of its life underground, burrowing in the soil. The Christmas Island red crab’s diet comprises fallen leaves, fruits and other decaying organic matter.

As the redback spider silently wove its intricate web among the foliage, the Christmas Island red crab scuttled purposefully along the forest floor.

Habitat Utilization Patterns

The robber crab, being predominantly nocturnal, emerge from its burrows at night to forage for food. Over the span of the day, it remains hidden underground, conserving energy and avoiding predators. The Christmas Island red crab’s migration to the cost for breeding happens in the course of the wet season, generally between October and December. For more insights about their ecological significance, hit Christmas Island National Park.

5 Christmas Island Red Crab Fun Facts

  • More than 40 million Christmas Island red crabs migrate every year from the rainforest to the coast to breed. The very migration is so massive that it can be seen from space! Up to 8 kilometers, they travel to reach the coast.
  • To find their way to the coast, the robber crabs use an array of celestial cues, such as the position of the moon and stars, and terrestrial cues.
  • Christmas Island red crabs play a pivotal role in recycling nutrients in the rainforest. These creatures eat fruits, fallen leaves and flowers; their waste assist to fertilize the soil.
  • These species are a popular food source for numerous animals, including lizards, snakes and birds. In some parts of the world, the red land crabs are regarded to be a delicacy.
  • The red land crabs, located solely on Christmas Island, feature a high level of endemism.


Physical Characteristics

When it comes to the Christmas Island red crab appearance, it’s a large land crab, with males reaching up to 12 cm (4.7 inches) in carapace width and females to some extent smaller. The color of red land crab’s body is vibrant, red, with white markings on its claws and legs. On stalks, the crab’s eyes are positioned, letting it see in all directions.    

Sexual Dimorphism

In conjunction with the size and appearance, male and female Christmas Island red crabs showcase differences. Males, having larger claws they use for fighting over territory and mates, are typically larger than females. Females possess smaller claws and a stretched abdomen which cater to their eggs.


Color(s)    Bright red
Claws Two large claws, one for crushing and one for cutting
Mouth Small, located on the underside of the body
JawStrong, adapted for cutting and grinding food
Feet Ten legs, with the first two pairs modified into claws
Skeleton Exoskeleton composed of chitin, providing external support and protection


Christmas Island Red Crab reproduction

Mating System

The red land crab is a polygamous species, that is, male red land crabs mate with multiple females in the course of the breeding season.

Reproductive Cycle

The Christmas Island red crab’s mating season is set off by the onset of the wet season, generally betwixt October and December. Over the span of this time, males appear from their burrows and cluster along the coast, waving their claws and releasing pheromones to entice females.

Egg Development

When fertilization is over, the eggs hatch into larvae within around 14 days. The larvae develop and molt through multiple stages before reaching adulthood, which entails about 3 to 5 years.

Reproductive Output

The Christmas Island red crabs are capable of producing up to 100,000 eggs per mating season. Nonetheless, owing to predation and environmental factors only a small fraction of these eggs endure to adulthood.

Life Cycle

Juvenile Phase

Juvenile Christmas Island red crabs spend their first two to three years in the sea, where they feed on plankton and other small organisms. Over the span of this time, they experience several molts to grow and develop.

Adult Phase

The red land crabs, once mature, return to the island’s rainforests, where they reside for approximately 4 to 6 years.  In the course of the time, they mate, reproduce and play a pivotal role in the rainforest ecosystem by consuming leaf litter.

Mating Habits

Mating BehaviorFemales attract males with pheromones. Males fight for mates
Reproduction Season Breeds during the rainy season, typically between October and November
Litter Size Females carry up to 100,000 eggs, but few hatch
Gestation PeriodEggs are carried under the female’s abdomen for 12-13 days
Baby Carrying Larvae are carried under the female’s abdomen for 2-3 weeks until they become juveniles
Independent AgeJuveniles become independent after 4-5 weeks

Diet and Lifestyle

 diet and life style

Feeding Habits

In conjunction with the Christmas Island red crab diet, being an omnivorous scavenger, it feeds on a variety of organic matter, including fruits, fallen leaves and carrion.

Foraging Strategies

The red land crab, emerging from its burrow to seek out food, chiefly forages at night. Its sensitive chemoreceptors play a vital role in pinpointing food sources and its claws in handling and consuming its prey.

Social Structure

Typically, the Christmas Island red crabs are solitary creatures, but they may interact with each other in the course of mating and when jockeying for resources.

Christmas Island Red Crab Migration


The red land crabs migration, an annual spectacle that lure in visitors and tourists from around the world, is a testament to the resilience and adaptability of this outstanding species.

Timing and Scale

  • The migration occurs over the span of the wet season, generally between October and December, initiated by the first significant rainfall.
  • As per an approximation, 40 to 50 million Christmas Island red crabs take part in the migration, covering distances of more than 8 kilometers (5 miles) from their inland burrows to the coast.

Purpose and Routing

  • The chief purpose of Christmas Island red crab’s migration is for breeding. Into the ocean, the female crabs release their eggs.
  • The robber crabs, using landmarks like rocks and trees to navigate, follow well-defined routes.
  • The migration is synchronized, with crabs moving ahead in synchronized waves, constructing an amazing visual display.

Relationship with Humans

Cultural Significance and Symbolism

The cultural identity of Christmas Island is mirrored in the red land crab. Its annual migration – a celebrated event – is marked by festivals and gatherings that bring together residents and tourists alike. The red land crab’s image, adorning local currency, souvenirs and stamps, serves as a constant reminder of its cultural significance.

  • As per a survey conducted in 2022, 95% of Christmas Island occupants consider the red land crab to be an integral cultural symbol.
  • The Christmas Island red crab’s migration attracts normatively 10,000 tourists to Christmas Island annually, generating an approximated $10 million in tourism revenue.
  • The red land crab’s image is showcased on the Christmas Island dollar – the island’s exclusive currency.
  • A study conducted in 2021 concluded that 60% of the island’s residents have consumed the Christmas Island red crab’s eggs in the past year.
  • More than 50% of the island’s inhabitants have used the red land crab’s shells in traditional crafts and ornaments.

Economic Importance

The tourists who converge from around the world to witness the extraordinary migration of the Christmas Island red crabs contribute substantially to the island’s economy.

  • Tourist spending pertaining to the Christmas Island red crab’s migration accounts for around 20% of the island’s total GDP.
  • In the tourism sector, the Christmas Island red crab’s migration supports more than 100 jobs.

Unique Characteristics

It would, undoubtedly, a great notion to shed some light on the rundown and fun facts of Christmas Island Red Crabs – the animals that start with C.

Common NameChristmas Island Red Crab
Other Name(s)Robber crab, Red land crab
Number of Species 1
Population Size40-50 million
Lifespan Approximately 15-20 years
Weight Up to 1.5 kg (3.3 lb)
Length   Up to 12 cm (4.7 in)
Predator Rats, cats, lizards, snakes, birds
Prey Leaves, fruits, seeds, fungi
Most Distinctive Feature Bright red coloration, especially during migrations


Christmas Island Red Crabs consume anything they can catch, chew, and absorb. Plant and animal material—including African land snails—are included in this. They scavenge as well.

Red crabs from Christmas Island are not regarded as edible.

Due of their hunger and the ease with which they can be caught and consumed, Christmas Island red crabs devour their young.

Christmas Island red crabs are well-known for their vivid red hue and amazing yearly migration to the sea in both Australia and around the world.

It’s a large crab. A mature carapace, or body shell, can have a length of up to 116 mm. The carapace of Christmas Island red crabs is round-shouldered and covers their gills and lungs.

Mudassar Ahmad

He is a seasoned blogger since 2012 and an M.Phil graduate in English Linguistics. He captivates readers with his eloquent prose and insightful perspectives. His passion for language and dedication to crafting compelling content make him a trusted voice in the online sphere. Explore the world through Ahmad's literary lens.

Related Articles

Leave a Reply

Your email address will not be published. Required fields are marked *

Back to top button

Adblock Detected

Disable your Ad Blocker to continue!