The Colossal Coconut Crab | South Pacific | BBC Earth

Summary

On the remote island of Vanuatu, the rubber crab, also known as the coconut crab, stands out as the largest terrestrial invertebrate. Weighing up to four kilograms and with a leg span of one meter, these hermit crabs thrive on coconuts, using their powerful pincers to crack open the tough shells. Despite their land dominance, they are not seafarers, relying on ocean currents to disperse their eggs and larvae in a 50-day race to find new homes above water.

Takeaways

• 🦀 The rubber crab, also known as the coconut crab, is the largest terrestrial invertebrate on Earth.
• 🌴 This unique species is found on the undisturbed islands of Vanuatu in the Pacific.
• 🐣 The largest rubber crabs can weigh up to four kilograms and have a leg span of one meter.
• 🌙 They are most active at night, thriving in environments with little competition from other native animals.
• 🤔 The reason for their large size remains a mystery, but it's suggested they have filled a niche usually occupied by medium-sized mammals.
• 🥥 Coconuts are a favorite food of the rubber crab, and they can carry them up to five kilometers to their dens.
• 💪 They are known to be the only animals capable of breaking into coconuts using their powerful pincers and legs.
• 🕒 The process of opening a coconut can take several hours, but it provides a protein-rich meal.
• 🏊‍♂️ Despite their land dominance, adult rubber crabs are not adapted to survive in the sea and would drown quickly.
• 🌊 The crabs' eggs are released into the ocean, relying on currents to disperse and find new habitats.
• 🐳 The larvae have a limited time of 50 days to find a new home above water after hatching.

Q & A

What is unique about the crabs found on the island in Vanuatu?

The crabs on the island in Vanuatu are unique because they are the largest terrestrial invertebrates on Earth, known as the rubber crab or coconut crab.

How large can the rubber crabs grow?

The rubber crabs can grow to weigh up to four kilograms and have a leg span of one meter.

What is the significance of the rubber crabs being referred to as 'hermit crabs on steroids'?

The term 'hermit crabs on steroids' is used to describe the unusually large size of the rubber crabs compared to typical hermit crabs.

Why do rubber crabs come alive at night?

The script does not provide a specific reason, but it is common for many crab species to be more active during the night.

What role do coconuts play in the diet of the rubber crabs?

Coconuts are one of the favorite foods of the rubber crabs, which is why they are also called coconut crabs.

How do rubber crabs break into a coconut?

Rubber crabs break into a coconut by using their powerful pincers to rip off the husk and then drilling through the germinating holes on the seed until the nut cracks.

What is the nutritional benefit of eating coconuts for the rubber crabs?

Eating coconuts provides the rubber crabs with a meal rich in protein.

Why are rubber crabs not masters of the sea?

Rubber crabs are not masters of the sea because an adult crab would drown in a few minutes if it entered the water.

How do rubber crabs disperse their eggs to reach new islands?

The female rubber crab carries thousands of eggs, which she releases into the ocean, allowing the eggs to be carried by ocean currents to new locations.

What is the survival challenge faced by the larvae of the rubber crabs after hatching?

After hatching, the larvae have only 50 days to find a new home above the water, which is a critical survival challenge.

What is the mystery surrounding the growth of the rubber crabs?

The exact reason why the rubber crabs have grown so large is still a mystery, but it is suggested that they may have filled a niche usually taken by medium-sized mammals due to the lack of competition on the remote islands.