Christmas Island Red Crab
There are fourteen land crab species on Christmas Island and the red crab is one of them. They belong to the arthropod family, which are joint-legged animals. The red crab is slow-growing and only counts once a year. Males are larger than females and can reach a carapace size of 116 mm. They reach sexual maturity when they are 40 mm across. Red crabs spend most of their lives in solitary burrows where they forage for fallen leaves, fruits, and flowers, as well as seedlings.
Christmas Island Red Crab Habitat
A native of Christmas Island, Australia, the red crab lives all over the island. In fact, there are tens of millions of them living on the island’s rainforest floor. A large part of their habitat is a swampy area with deep soil. In addition to living on fallen leaves and seeds, they also live in cracks in rock outcrops. The population of these crabs was estimated to be 120 million in the 1980s, but is now believed to be less than 50-60 million.
The red crab’s diet is based on the detritus and litter left behind by other animals. Its larvae never make the trip back to the beach, but their eggshells do. Because of the abundance of Christmas Island red crab eggs, manta rays and whale sharks gather close to the island to feed on the larvae. Despite these challenges, the red crabs’ survival rate is high enough to ensure that enough of the species survives.
The red crabs spend the majority of their time outdoors in their burrows. They live in sheltered locations, blocking the entrance with leaves or other debris. Then they rest for months, estimating. Then they emerge from their burrows after rainy seasons. Their survival depends on their seasonal cycle of wet and dry seasons. Climate change can throw this seasonal pattern out of whack. One female crab can lay as many as 100,000 eggs.
To preserve the Christmas Island red crab, scientists have taken measures to help it adapt. They introduced about 300 tiny wasps to the island from Malaysia. These insects eat scale insects, the primary food source of the invasive, destructive crazy ants. In addition to being pests, the wasps also have other beneficial effects. Some of these insects are able to dig mating burrows. Its presence has helped save the Christmas Island red crab from extinction.
Christmas Island Red Crab Diet
The diet of the Christmas Island red crab is similar to that of shrimp, but the meat is more flavorful and slightly chewy. They can be found in specialized seafood stores. In addition to the red crab, they are also available in many other varieties of crustaceans. This crab is not considered endangered, but the food it offers is considered a delicacy in some Pacific Islands. You can even find Christmas Island red crab meat in restaurants, if you know where to look.
The Christmas Island red crab spends its dry season in its burrow. In order to survive in this environment, the red crab must be in a moist environment. It will drive off trespassers and will stay in the same burrow for five years. The burrow is lined with leaf litter, which encourages plant growth around the entrance and acts as a fertilizer. The red crab’s diet varies from year to year, depending on the availability of resources.
During the breeding season, the Christmas Island red crab produces up to 100,000 eggs. This population was controlled by the Maclear’s rat, a natural predator. However, the yellow crazy ants accidentally introduced to the island have killed between ten and fifteen million red crabs. The larvae are eaten by fish, sea grasses, and whale sharks, which also time their visits with red crab breeding season.
The red crab spends drier months of the year in their dens. These burrows retain moisture, and they spend the wet season migratory, which is usually October to November. However, this migration is controlled by the moon phases and amount of rainfall. If the rainy season is long enough, the red crab will migrate. That’s why the diet of the Christmas Island red crab is so important for the ecosystem.
Christmas Island Red Crab Migratory cycle
Red crabs on Christmas Island are famous for their annual migratory rituals. During the rainy season, these iconic creatures put on a spectacle as they march toward the sea to spawn. But a change in rainfall patterns can halt or even cancel this migratory ritual. To find out why, scientists studied 36 years of data from Christmas Island. The researchers also looked for a relationship between rainfall and spawning events.
In this study, Shaw and Kelly collected data from the last 36 years, comparing it with actual measurements of rainfall. This study found that crabs generally travel in straight lines, with most of the animals heading toward the northwest shore. It also showed that the timing of the migration cycle was significantly different between study seasons in 1993 and 1995. Nevertheless, the moon phases fixed the date of spawning. In other words, the crab’s migration cycle is regulated by the lunar cycle, as the late rainy season can speed up its journey.
The migration of Christmas Island red crabs begins in November, when rains begin on the island. Males guard their mating burrows for two weeks, while females lay eggs inside them. After two weeks, the females emerge from the muddy ground on high tide, just before the new moon in December. The female crab then releases millions of eggs into the sea. The migration cycle of Christmas Island red crabs is a fascinating example of evolution.
Moreover, the red crabs’ reproductive cycle is linked to precipitation and the phases of the moon. Climate change may disrupt this natural cycle, affecting animals that depend on migratory activities. In the meantime, scientists must try to understand why this species migrates and what causes it. The red crabs depend on a seasonal cycle, and a sudden change in rainfall could throw the entire migration process off track.
Christmas Island Red Crab Protection
The Christmas Island red crab is a large species of land crab that grows to more than 116 millimetres across. The claws of this species are usually equal in size, and they regenerate if they get injured. The male Christmas Island red crab is larger than the female, with a larger abdomen and narrower claws. The female grows a broader abdomen only in her third year of growth. It is important to protect this species from human interference by following the guidelines for protecting this species.
The island is a true tropical paradise, and man only began to approach the land in the past few centuries. Today, 65% of the island is protected, and a national park has been established to preserve its tropical rain forests and endemic species, including the red crab. Some roads have been closed to protect the crabs, while public notice boards provide updates on crab migration. It is possible to get up close to these creatures, but the island’s residents and tourists must stay at least one km away from them.
Red crab migration has begun on Christmas Island, and the first rainfall of the wet season usually starts in October or November. Red crabs must carefully time their march, and spawning is done at the last quarter of the moon, during the receding high tide. These seasonal changes can affect the migration pattern and thus threaten the species’ survival. Therefore, it is essential to protect red crabs and their habitat. With climate change and changes in rainfall patterns, wet season migration will be disrupted and the red crab population may suffer.
While the Christmas Island red crab is a solitary animal outside of breeding season, they are still able to protect their burrows from other red crabs. The crabs’ diet is diverse and they depend on scavenging for their food. This means that they have virtually no competition for food and will dominate the forest floor. If the population declines, the island will be ruined. The government is considering ways to protect the species, and many of these measures are already underway.
Christmas Island Red Crab Wasps
The release of small wasps on Christmas Island to control yellow crazy ants could be the key to saving the red crab. The tiny creatures, which have a wingspan of just three millimeters, feed on the larvae of a particular insect called the yellow lac scale insect. By attacking the yellow lac scale insect, the wasp produces more wasps. In its native habitat, the yellow lac scale insect is rare, so releasing wasps on the island could help keep the crazy ants in check.
Yellow crazy ants were accidentally introduced to Christmas Island during the 19th century, but their population soon multiplied. By 2002, the ants had occupied 6,000 acres of the island, with two-thirds of that territory protected by the federal government. The ants kill red crabs by spraying acid into the crabs’ eyes, causing the animals to dehydrate and die. Yellow crazy ants are also the main source of food for the crazy ants that have been destroying the Christmas Island red crab population.
In other parts of the world, wasps have been used to control invasive insects such as cane toads and mongooses. Although the new species may not have an immediate impact on red crab populations, there is an underlying solution to the red crab problem: introducing the micro-wasp to the island is an ongoing process that will require many years to complete. However, if it does succeed, the island could be free from invasive species within a few years.
While there are no confirmed reports of the release of micro-wasps, this species is already being used as a biological control on the mainland. Researchers have studied the impact of these introduced species on the red crab population. They found that micro-wasps are effective in controlling the scale insects without causing a threat to other wildlife. Moreover, it has no negative impact on humans or native species. There are no known adverse effects of these micro-wasps on the Christmas Island red crab.