Crabs - More Than A Little Armored Creature

Previously, in We Call Them Crustaceans, I talked about some real basics about crabs as a species. Crabs are also camouflage-artists. Some of them take sponges instead of anemones for partners. Some rob the sea squirt of his tunic and wrap up in that. Some, like the Spider crabs of our deeper waters, bedeck themselves with seaweed so that they cannot be suspected of being crabs at all.

They scissor-off cuttings of the weed or of sponge, plant them on their shells, and the cuttings grow where they have been placed, and a moving garden of weed masks the crab within.

Other common crabs are crawlers rather than swimmers, we must remember that there are crabs which swim powerfully. We have several species of swimmers in American waters, but the common edible Blue crab of our markets and the mottled Lady Crab are the most common.

Our waters contain some notable species in the spider like Slender-beaked Crab, the great Thornback Spider Crab, and minute Pea Crabs which, instead of carrying about anemones or sponges or seaweed, take up their residence within the shells of our common bivalves living safely in an animate fortress whose food they share.

However, let's take a look at land crabs of the tropics.

We come to creatures which must still go down to the sea to lay their eggs as frogs must go back to the pond and ditch for the like purpose. However, they themselves, like those amphibians, drown if confined to the water. One which lives on the verge of the sea burrows into the sand. Then, having roughly made its hole, it ejects a strong stream of water from its gills, so clearing a passage for breathing and is content.

Other crabs go miles away from the sea. Some of them are best know to us by the famous Calling Crab, a title coming from the fact that the crab has one of its foremost claws hugely developed and carries it high and forward when running in such a manner as to suggest to onlookers that it is beckoning someone.

These crabs live ashore except for the egg-laying period. Congregating in swarms, they make great burrows in the sand, like rabbits, combining their efforts with intelligence and art.

Experience teaches us not to look for our crabs far from sea, but in the tropics there are Hermit crabs which take up their homes and walk far inland.

They carry with them large turbo shells. Travelers have found these shells, some empty, some containing the hermits which transported them, a thousand feet up a mountainside. I've even once knew a naturalist who sought to gather some blossoms high in a tree, only be be severely bit by a crab he never saw until too late.

Then there are land crabs which crawl about dry docks and do not go to sea.

The Grapsus strigosus, a little horror of a crab, first given its due place by the naturalists of the Challenger expedition. While the party was fishing and bird hunting on St. Paul's Archipelago -- they found themselves surrounded by swarms of crabs, which stole the bait and carried off the fish as they lay new-drawn from the waters.

That was not the worst. Nesting terns had been driven from their young in order that these might be examined, so a big old crab waddled into a nest and seized and carried off a young tern to devour it alive at leisure.

On Pitti Island, in the Indian Ocean, travelers have told of the ground so thick with the remains of young terns, some reduced to clean-picked skeletons, all murdered by crabs.

Other crabs regularly raid rabbit warrens, and still others banquet on coconuts. The pal-hunters are usually known as "robber crabs."

It has long been known that the Robber Crabs (aka Coconut Crab) fed on coconuts, but that they climbed the tall palms in pursuit of their booty was formerly deemed a tall tale of fabrication. It turned out that that old time traveler's tale is true.

So how are crabs to obtain the meat of the coconut, enclosed in a very hard shell and in that dense of fiber?

When you think of Robber Crabs, think giant crabs. Having climbed his tree and brought down his prize, the crab tears off the fiber strip by strip. Then it hammers out the "eyes" of the nut with his great claws.

Having gained an entry, he inserts his thin hinder claws, and with these drags out the contents of the nut.

These Robber crabs, big blue fellows, more like lobsters than crabs, can bite a man's finger off, as members of more than one expedition did at Christmas Island, in the Indian Ocean.

Additionally, there are land crabs which, when they make their annual migration to the sea, go straight as lemmings on the march. They swarm over houses. They swarm through them.

The Christmas Islanders found themselves bitten in their beds as the swarming crabs made their pilgrimage to the distant ocean nursery. The whole island is covered with them as they swarm each season.

Then there are the land crabs of Trinidad. Travelers of yesteryear have told of the swarms of yellow and pink crabs, with dead yellow staring eyes peeping from behind very nook and boulder, as if to say, "You drop down among us and we will do the rest."

I had an old timer, Edward Knight, told me the story of how with two companions camping in Trinidad -- they awoke in their tent as victims of a massed assault by the little wretches. They began to gnaw the sleepers in their camping rolls. He claimed:

"They would have devoured us had we not awoke. As it was, they did nibble holes in our clothes."

Perhaps they should have realized the land crab problem earlier as when they first landed and cooked their evening meal of fish, swarms of crabs were drawn down the nearby mountainside. Horrified and amused, they threw them lumps of fish which they devoured with crab-like slowness, yet perseverance.

Mr. Knight reported that:

"A huge beast was standing a yard from me. I gave him a portion of fish and watched him. He looked me straight in the face with his out starting eyes. He proceeded with his two front claws to tear up his food, bringing it to his mouth as though he had a fork."

"The entire time he never looked at what he was doing. His face was fixed in one position, staring at me. And when I looked around, lo and behold, there were half a dozen others all steadily feeding, but with immovable heads turned to me with that fixed basilisk stare. It was indeed horrible, the effect nightmarish in the extreme. Never to be forgotten."

At the time the story was being told, I would have disbelieved it and thought it another old man telling me a fishing or camping story that was greatly exaggerated or made-up -- however, the sheer look of terror in Mr. Knight's face told me otherwise.

Remember, after all that feed of fish, it was these same monsters that attacked the men sleeping as they lay in their tent that night. "Remind me to never go camping in Trinidad," was what I whispered to my husband after an evening of drinks and dinner with Mr. Knight.

No discussion about the Christmas Island crabs should not include a little about the island itself. Known to explorers since the early 17th century. It has a rich history, even in today's times that is worthy of exploring. Uninhabited until the late 19th century, it has a unique scientific value in that it's one of the few places on earth that has not suffered in the extreme in terms of man's mark or blight upon it.

On Christmas Island, there are twenty different species of crabs. Over a dozen of them are true land crabs (dependent on the ocean for species survival). The Robber crabs are the largest in number there.