We have seen that worms are found in nearly every part of the globe, that they are very numerous, as many as 348,480 having been found in an acre of rich ground in New Zealand, and that by the peculiar economy of their nature they are fitted to accomplish a great deal of good in the earth. They have played a more important part in the history of the world than most persons would at first suppose. In many parts of England, according to Darwin, a weight of more than ten tons of dry earth annually passes through their bodies and is brought to the surface in each acre of land, so that the entire superficial bed of vegetable mould passes through their bodies in the course of every few years; and in most parts of the forests and pasture-lands of Southern Brazil, where several species of earth-worms abound, the whole soil to a depth of a quarter of a metre looks as though it had passed through the intestines of worms, even where scarcely any castings are to be observed upon the surface. The upper crust is continually being eaten and ejected by them, thus aiding the fertility of the soil, as well as conveying water and air to the interior by the myriads of burrows which they drill. The vast quantities of leaves that they drag into their holes tend also to enrich the ground. Nor does their good end here. They cover up seeds, undermine rocks, burying them up, and to their labors is due the preservation of many ruins and ancient works of art. Numerous old-time Roman villas have been discovered beneath the ground in England, whose entombments were undoubtedly caused by the worms that undermined them and deposited their castings upon the floors, till finally, aided by other causes, they disappeared from sight.
When a wide, turf-covered expanse of earth is beheld, we would do well to remember that its smoothness, upon which so much of its beauty depends, is largely due to all the inequalities having been slowly levelled by worms. That all the surface-mould of any such expanse has passed, and will again pass, every few years through the bodies of worms is a marvellous reflection, and one which should not be lightly dismissed from the mind. The most ancient, as well as one of the most valuable of man’s inventions, is the plough. But long before man existed the land was in fact regularly ploughed, and still continues to be ploughed, by earth-worms. No other animal has played such a part in history as have these lowly-organized creatures. True it is that corals, which are still lower in the scale of animals, have performed more conspicuous work in the innumerable reefs and islands they have built in the great oceans, but their work is confined to the tropical zones, while that of the earth-worm is well-nigh universal. Verily it is by the little things in life that the Creator has erected the most stupendous monuments to show forth His infinite power and wisdom.
FIDDLER- AND HERMIT-CRABS.
Among our first acquaintances of the sea-shore are sure to be a number of merry little sprites which do not seem to have yet mastered the lesson of walking straight ahead. Their movements will be seen to be in a direction at right angles to that towards which the head points. It is a very interesting sight to watch these apparently one-sided creatures hurrying off in their lateral progression towards their burrows in the sand or mud, or in quest of food. Pass them, and you will be surprised to see how quickly some of them will reverse their motion, seemingly without so much as pausing to glance at their pursuer, their machinery appearing to have given out at one end, thus compelling them to reverse and travel back over their old courses.
These little Fiddler- or Calling-crabs, as they are termed, are the most pronounced offenders against the commonly accepted rule of proper walking. Scattered all over the salt marshes and mud-flats, at about high-water mark, may be noted their burrows, which are about as large as a thrust made by an umbrella point, and from which can be frequently seen the little animal peeping forth, preparatory to making a sally. At another part of the flat, where the noise of your footsteps has not given signals of danger, hundreds of crabblings are busy with their out-door occupations. Draw near to them, and away they scamper to their dwellings, males and females intermingled promiscuously, the former recognizable by the undue development of one of the claws, which is carried transversely in front of the head. When the animal is provoked, this claw is brandished in a somewhat menacing manner, which has been likened by some to the pulling of a violin bow, and by others to the action of beckoning or calling, and hence the names which have been applied to these eccentric creatures.
Have you a desire for a more intimate knowledge of the animal, take him up by the big claw, and you can now examine him without the least fear of incurring the proofs of his displeasure. Two bead-like, compound eyes, supported on long stalks, which can be readily withdrawn into the protecting shield of the carapace, will be observed. From the manner of this support, which allows of vision in almost every direction, the name of stalk-eyed crustaceans has been given to the group in which this structure is found. The two pairs of feelers, which you see in front of the eyes, are known as antennæ and antennules. They are of peculiar interest, for, aside from acting as feelers, they subserve the functions of smelling and hearing, the auditory apparatus being lodged in the base of the smaller pair. There are ten feet, and this is a character of importance, as it is a feature distinctive of the ten-footed, or decapod, crustaceans. At first sight it appears that the animal is devoid of a tail, but if you turn him over upon his back you will find a very short one tucked safely under the body. A comparison of our study of this crab with that of the lobster or cray-fish will show that the tail, or, more properly, the abdomen, is stretched out beyond the body proper, and that the elongation is in proportion to the length of the animal. Two distinct groups of ten-legged, stalk-eyed crustaceans are thus recognized, namely: the short-tailed forms, or crabs, and the opposite, or long-tailed forms, to which the lobster and shrimp belong, the hermit-crabs constituting an intermediate type.
Two species of the Fiddler, considerably resembling each other in color and ornamentation, are to be found upon our Atlantic Coast. The more common form, Gelasimus vocator, has a smooth, shining carapace, while that of Gelasimus minax is finely granulated and in part tuberculated, the back of both appearing impressed with a figure very similar to the letter H. The latter, which appears to be a vegetable feeder, is the larger, its burrows not infrequently measuring one and a half inches in diameter. Estuarine regions, in close proximity to fresh water, rather than the tidal flats, are its habitat, and, in truth, it seems to be able to get along for weeks, and even months, without any absolute need of salt water.
FIDDLER-CRABS.
Two Males Fighting for a Female.
In the excavation of their homes the Fiddlers throw up the pellets of moist earth by means of their anterior walking legs, depositing their burden usually at some little distance from the mouth of the burrow. As winter approaches, the domiciliary apertures are closed up, and the famine of winter is spent in a state of torpidity.