Part 16

The favorite food of cerebratulus lactus is said to be another abundant burrowing worm, the nereid, which is nearly as large in diameter, belongs to a higher order, and has powerful biting jaws. The victim always is swallowed tail first. Its burrow is a U-shaped tube in which it is unable to turn around. The nemertean probes through the mud for the tail end in such a burrow. The nereid, seized from behind, cannot bring its fighting apparatus into use. Actually, however, it never appears to struggle against being swallowed—a remarkable fact since nereids fight fiercely among themselves. The reason, it has been postulated, is that the victim’s nervous system is paralyzed by the poisonous slime excreted by cerebratulus. When a minute drop of this is placed on the tongue, it parches the whole mouth and the intensely bitter taste remains a long time. The worm requires about ten minutes to swallow a nereid, but by that time the prey is half-digested. The flow of this mucous is quite copious. When several healthy worms are placed in a pail, the bottom is soon filled with a hardening mass of it from which the animals must be cut or pulled. When crawling, the worm exudes a mucous trail, like a snail.

A comparable Mediterranean species, Nemertes borlasi, was described by the French naturalist Quatrefages:

“This gigantic worm is from thirty to forty feet long, brown or violet, and shining as varnished leather. It lurks under stones and in hollows of rocks where it may be met with, rolled into a ball and coiled in a thousand seemingly inextricable knots which it is incessantly loosening and tightening by contraction of its muscles. The animal is nourished by sucking a kind of small oyster which attaches itself to various substances under water. When it has exhausted the food around, it extends its long, dark-colored, riband-like body, which is terminated by a head bearing some likeness to the head of a serpent. It pauses gently, moves from side to side as if endeavoring to investigate the ground, and finally succeeds in finding a stone to suit its purposes about fifteen to twenty feet from its former retreat. It then begins to unwind its coil and arrange itself in a new domicile. In proportion as one knot is loosened, another forms at the opposite extremity.”

A report of the Gatty Marine Laboratory of St. Andrews University in Scotland tells of the species Cerebratulus angulatus, which was mistaken for a fish. “But when the fisherman stretched out his hand net to capture it, instantly to his astonishment it shot out to more than a yard long. In the laboratory it swam with undulatory up-and-down movements, as an eel swims laterally.”

The nemertinea are a progressive race. Some have invaded the deep sea and some the dry land. They have been obtained from depths of more than 6,000 feet. The deep-sea species have undergone peculiar adaptations for a life of swimming slowly or floating idly at whatever depths they have chosen for their habitat. They have lost their eyes and their brains are quite rudimentary compared with those of their land or shallow-water relatives. All have increased greatly the amount of gelatinous tissue between the internal organs, so that they have a low specific gravity. The deep-sea forms thus far collected are broad and flat. Some have taken on the appearance of small fish with outgrowths on the sides of the body which resemble fins, and with the rear end flattened like a fish’s tail. Some have developed tentacles around their mouths.

Most of the ribbon worms of the open sea are nearly transparent. Some, however, are among the most brilliantly colored of the nemertinea race, with coat patterns of yellow, orange, red, and scarlet. Most of these creatures are small, measuring only a fraction of an inch in length. The largest is about six inches long—thus, as one biologist points out, comparing to the smallest like an ox to a mouse. These pelagic species are found in all the oceans. They are carried around the world by deep-sea currents.

About twelve species have abandoned the shore for dry land where they lead active lives and seem to have become almost independent of water. They cannot, however, endure being completely dried out. They do not make their own burrows, but in periods of drought, it is believed, they make use of earthworm burrows. Some have been found under the dead, damp bark of tropical trees. Their chief food consists of earthworms.

Winged Reptile

The largest flying animal the world has known was a winged reptile, the pterodactyl, of a hundred million years ago. It had a wing spread of more than twenty feet, supporting in the air a body which would hardly have weighed more than thirty pounds. Its head was nearly four feet long with a dagger-like, narrow, pointed toothless beak. It lived around the ancient sea which once extended northwestward from the present Gulf of Mexico through most of Kansas. Presumably it lived entirely on fish and made long, gliding flights over the water.

The structure of this reptile, insofar as it could be realized from fragmentary fossil bones, was studied carefully by Dr. Samuel P. Langley while he was at work on early models of his airplane. Did the pterodactyl, Dr. Langley asked in a somewhat pessimistic progress report, represent the best Nature could do in the way of flight? Could man hope to do better than Nature?

Vicious Fire Ants

One of the most vicious of insects is the fire ant of South America—a small red ant whose sting burns like the point of a red hot pin pushed into the skin. Hordes of these creatures have forced the populace to abandon Brazilian towns. The soil of a village can be completely undermined by the ants. The ground is thoroughly perforated by the entrances to their subterranean galleries.

“The houses are overrun by them,” says Edward Bates in A Naturalist on the Amazon. “They dispute every fragment of food with the inhabitants and destroy clothing for the sake of the starch. All eatables must be suspended from rafters in baskets, with the cords well soaked in balsam, the only known means of preventing the ants from climbing. They seem to attack persons out of sheer malice. If we stood for a few hours in the street, even at a distance from their nests, we were sure to be overrun and severely punished. The moment an ant touched the flesh he secured himself with his jaws, doubled his tail, and stung with all his might.”

The Architectural Genius of Birds

Birds rival ants and termites as architects. One species builds nests as big as small human dwellings—as much as 25 feet long, 15 feet wide and ten feet high. This is the sociable weaver bird of the desert western areas of South Africa. Such an apartment house, woven out of sticks and straw, may contain as many as 95 individual nests. It is the community product of a flock of from 75 to 100 pairs. The sheer bulk of the nesting material gathered is striking evidence of the impelling year-round urge of the building instinct.

This bird, says Dr. Herbert Friedmann, Curator of Birds at the Smithsonian Institution, “is about as sociable as any bird could possibly be. It is always found in flocks, feeds in flocks, and breeds in the large, many-apartmented compound nests. With this extreme socialibility and sedentary habit of life the territorial relations of the species have been modified in a way that is quite remarkable, perhaps unique, among birds. Instead of each pair having its own breeding territory, each flock seems to have a definite territory whose boundaries are seldom crossed by individuals of other flocks.

“In an area of approximately 1,000 square miles I found only 26 nests. The flocks ordinarily do not live in very close juxtaposition to each other. The nests are so large, so conspicuous at great distances, and the trees so relatively few in number that I am quite certain I found practically every nest in the area.”

In spite of the highly developed communal life, Dr. Friedmann notes, there appears to have been no break-down of the family. Whether each male has one or several mates, however, is unknown. In the construction of the apartments there is some evidence that each family builds its own individual nest, while the whole flock cooperates in constructing a roof over the whole. The structures often become so heavy eventually that they crash to the ground and all the work must be done over.

Woodpeckers that carve “apartment houses” out of hardwood tree trunks have been observed by Dr. Alexander Wetmore in the dark, rain-drenched forests of the La Hotte mountains in Haiti. On one occasion he was astonished to find a dozen pairs going in and out of nests in a single dead tree trunk standing in an open space, the holes being from three to ten meters from the ground and in some cases less than a meter apart. There was no question that the woodpeckers were colonizing, as the trunk was a veritable apartment house with the birds climbing actively over its surface and flying back and forth to the nearby woodland.

In the same mountains Dr. Wetmore found another apartment builder, the palm chit-chat. It is a gregarious species that lives in small bands, each being made up of several pairs having a communal nest as the center of its activities. The largest bands frequenting a single nest do not appear to contain more than 20 birds.

The nests are constructed of twigs about the size of a pencil and from ten to 17 inches in length. The bird itself is only seven or eight inches long. Yet it is able to carry these heavy “timbers” 30 or 40 feet from the ground. One of the nests examined was about the size of a bushel basket and evidently was occupied by only a few pairs. There was a roughly defined central tunnel four to five inches in diameter leading through the mass of sticks and opening to the outside at either end. Near each end was a slight accumulation of bark that made a little platform.

The “apartments” opened from the tunnel on each side. There was a central chamber, supposedly a community room, about five inches in diameter, its floor carpeted with fine shreds of bark. Each nest was a separate unit, with its own door to the outside. There were, however, roughly defined passages running through the interlacing twigs at the top of the nests that permitted the birds to creep about under cover.

One of the most intricate of all bird nests is that of the South African penuline titmouse, distantly related to the American chickadees. It is made of a wool-like plant fiber, very intricately and delicately woven. The form is that of a small bag hanging from a thorn bush. It has one visible opening, a false one which leads nowhere and apparently is intended entirely as camouflage. The real entrance is skillfully hidden, its location known only to the builder. When the mother bird enters the nest she lifts a concealed flap, slips through, and closes it behind her. She again closes it just as carefully when she leaves the nest. There is not the slightest indication on the surface of the finely woven fiber of the existence of the flap.

The Ceylon tailor bird, orthotomus sutorius, makes its nest by actually sewing large leaves together in the shape of a horn, using its bill as a needle. As described by the British naturalist A. G. Pinto: “The first thing she did was to make with her sharp little beak a number of punctures along each edge of the leaf. Having thus prepared the leaf, she disappeared for a little and returned with a strand of cobweb. One end of this she wound around the narrow part of the leaf that separated one of the punctures from the edge. Having done this she carried the loose end of the strand across the under surface of the leaf to a puncture on the opposite side where she attached it to the leaf, and thus drew the two edges a little way together. She then proceeded to connect most of the other punctures with those opposite them, so that the leaf took the form of a tunnel converging to a point. The under surface of the leaf formed the roof and sides of the tunnel. There was no floor to this, since the edges of the leaf did not meet below, the gap between them being bridged by strands of cobweb.

“When lining the nest the bird made a number of punctures in the body of the leaf, through which she poked the lining with her beak, the object being to keep it in situ. All this time the margins of the leaf that formed the nest had been held together by the thinnest strands of cobweb, and it is a mystery how they could have stood the strain. However, before the lining was completed the bird proceeded to strengthen them by connecting the punctures on opposite edges of the leaf with threads of cotton. She would push one end of a thread through a puncture. The cotton used is soft and frays easily so that the part of it forced through a tiny aperture issues as a fluffy knob, which looks like a knot and usually is taken as such. As a matter of fact, the bird makes no knots. She merely forces a portion of the cotton strand through a puncture and the silicon in the leaf catches the strands and prevents them from slipping. Sometimes the cotton threads are long enough to admit of their being passed to and fro, in which case the bird uses the full length.”

The leaves are not killed by the tailoring process and remain green. Hence the nest is almost impossible to detect.

The Ferocious Leech Worms

Armies of billions of ferocious worms defended and preserved a fabulous 1,000-year-old Arabian Nights kingdom for three centuries. This kingdom was templed Kandy in the center of Ceylon, encircled by low, densely forested mountains. It was the site of one of the most picturesque ancient civilizations of the Orient which had degenerated into a brutal despotism when the first European invaders, the Portuguese, came to the island early in the sixteenth century.