Mark Pierrot with coconut crab

Mark Pierrot, an Australian, poses with a coconut crab on Christmas Island

While on vacation, people love to pose and take pictures.

And they won’t just pose with friends or family.

No. Tourists love to pose with just about anyone or anything that will raise eyebrows, open mouths and increase the number of likes they get on their Facebook page.

Sunsets….Statues….Famous people…..giant crabs

Giant Crabs?!

While on vacation on Christmas Island, Mark Pierrot, an Australian, posed in a photo with the world’s largest arthropod, a coconut crab, on Dolly Beach. Since then, the picture (featured on the Huffington Post) has caused quite a stir due to the crab’s massive size and intimidating stature. The coconut crab that Pierrot posed with was so large, he needed to lift its body with two hands! In an email to the Huffington Post, Pierrot says, “They look scary but are gentle giants, really.” 

Coconut crab

(Photo by Mark Pierrot)
Coconut crabs are the largest living arthropods

Weighing up to 70 pounds and measuring up to 3 feet in length, coconut crabs are the largest arthropods in the world! Arthropods are a group of animals that include spiders, crustaceans and insects. All arthropods are invertebrates and have an outer exoskeleton that protects their vital organs instead of an inner exoskeleton. Even though the Japanese Spider Crab is considerably bigger than the coconut crab, it is lighter due to living its entire life underwater in a weightless environment.

Coconut Crabs inhabit several small islands in the Pacific and Indian Oceans. One of the largest populations of coconut crabs can be found on Caroline Island while other islands exhibit very small populations or no populations at all. True to their name, they do consume coconuts but also like to eat fruit, smaller crabs and have even been observed to hunt rats that co-inhabit the islands they live on! Also known as palm thieves or robber crabs, these ginormous arthropods will repeatedly whack a coconut with their pincers until it cracks open and strip off the husks. In addition to being a food source, coconut crabs like to line their underground burrows with coconut fibers. These crustaceans spend the majority of their lives on land with the exception of going back out to sea to lay their eggs.

Coconut crabs are nocturnal and prefer to spend the majority of their day hiding in either their underground burrows or rocky crevices. These creepy crustaceans live super solitary lives with the exception of males and females gathering together to mate. A romantic interlude occurs on the beach close to the water. A female coconut crab generally lives within 100 meters of the water in order to keep her body from drying out when she produces young. The young coconut crabs (called zoae) hatch in the water where a female will deposit her eggs. The zoae then undergo several stages of growth and transformation before they become juvenile crabs. Juvenile crabs will continue to grow and live in a soft shell for 1-2 years; all the while living almost completely underground so as to avoid being eaten or injured during this fragile stage of their lives.


coconut crab

The largest land arthropod in the world

Very little is known about the population or conservation status of coconut crabs. It has only been within the past few years that official, scientific surveys of their populations have been conducted by researchers. For example, the London Zoological Society began conducting surveys of coconut crab populations on three atolls in the Chagos Archipelago back in 2014. It has been observed that, even though they occasionally hunt and consume rats, rodent populations introduced to some of the islands the crabs inhabit have turned the tables and have reduced the local crab populations by hunting them in turn! It may take several more years for sufficient data to be gathered to see if whether or not coconut crabs are even a threatened or endangered species.

So the next time you go on a tropical vacation and are looking for that perfect Facebook post, take a picture with a giant crustacean! You will hit that 1.000 “likes” landmark in no time!

Written by: Julie ‘Jules’ Cremer


Works Cited:

  1. Golgowski, Nina. “Holy Crab! Fearless Australian Poses with Massive Coconut Crab”. Huffington Post. 7th February, 2016. Web. Accessed 17th February, 2016.
  2. Marshall, Michael. “Coconut Crabs Are the Biggest Arthropods Living on Land”. BBC Earth. December, 2014. Web. Accessed 17th February, 2016.