Almost Paradise Pt 58 Crab Nightlife

(04 May 88) Coconut crabs are creatures of the night. Like vampires, when the first rays of dawn start to penetrate the thick jungle foliage on Namur, they stop their food gathering and retreat to their underground habitats.

They even shy away from moonlit nights. The coconut crab population begins to thin out as the moon goes through its stages until a full moon shines above the lagoon. Then, not a crab can be found anywhere.

There are two grass-covered roads that intersect in the middle of the jungle on the east side of the island. The first night I drove through  I encountered a half dozen crabs of different sizes and colors. The smaller ones were blue or purple and the larger ones mostly maroon or brown. I watched them for a while and discovered they were grazing on the grass. Some crabs would eat the grass on the spot while others would pull out clumps and drag them into the bushes, probably to be stored in their underground homes for later consumption.

I managed to approach to within a foot of one crab, trying not to spook it. The crab, however, was intent on its task. With the larger of its two claws it would snap off a blade of grass. Instead of depositing the grass in its cavernous mouth like the crab on the coconut, it held the blade close to the opening. Then one of two flexible antennae, located on each side of the orifice, wrapped itself around the grass and finished the transfer to the “mouth”. Click to enlarge. Click again for full size image.

The crab broke off another piece of grass and by this time I had focused with my camera and made a flash setting. When I snapped the picture, the creature froze, then dropped the morsel and beat a hasty retreat (for a crab) in reverse, maintaining a constant vigilance on its adversary with the bright light.

If a crab feels threatened it may decide to stand its ground. At this point the crab will hunker down on its rear end and bring the two large claws together in a boxer’s stance. One of the smaller, outer claws will strike out in a jabbing motion, perhaps a crustacean form of martial arts (Crab-Fu?).

I came across a large brown crab one night and got very close to check it out with my flashlight. The crab put its two claws together and began striking out with one of the smaller appendages on its right side. I was checking in an area behind the front claws to see if the creature had been in the process of eating when the larger of the claws grabbed the front of my flashlight and shoved it back at me with considerable authority. It felt like there was a full-grown man behind the claw. I was impressed.

I stood up and moved to my right and the crab rotated with me, still holding its defensive posture. No matter which way I went, it kept me to its front. I finally left and the big guy (gal?) swaggered off down the grassy trail and into the underbrush.

Crabs spend a lot of time trying to just scrap off the husk from a coconut. The crab will use one of its outer claws to hold the coconut in place while it strikes the husk repeatedly with its larger front claw and scrapes off layers of the covering.  This work can take several nights and the crab that started the peeling process might not be the one that gets the prize inside. A friend of mine told me he saw a crab carrying a husked coconut over its head across the road, evidently to its burrow. That would explain why I’ve seen plenty of husks scattered on the ground but not one nut.

The real threat to the coconuts are the rats that arrived on the island aboard ships. Namur Island is loaded with rats. They scurry about morning, noon, and night. They run up and down inside the ALTAIR building looking for donuts or anything available. You can tell if a rat has opened a coconut by the hole on one end of the nut, right through the inner wall.

Since the Marshallese are no longer here to harvest the coconuts and the U.S. government doesn’t care to, the rats have free run of the jungle area. Workers at Roi Namur call themselves Roi Rats and even have a logo.