Skilled builders are at work night and day in Vermont and New Hampshire. Some are architects with a flair for design; some are carpenters who cut raw materials to length; some are engineers who create technically efficient structures; and some are persnickety masons searching for just the right stone. If you think they are two-legged and speak our language, you’re mistaken. Most have six legs, some eight, some none at all, and not one of them says anything I understand.
Many species of amoeba, each with its own name, build houses as protection from microscopic predators. One such pond resident cements tiny bits of quartz together into a symmetrical, urn-shaped house. The fragments fit together so closely that a smooth surface results, inside and out. A cousin decorates the top of its urn-house with long, tapering spines made of carefully selected particles. Each species of house-building amoeba can be deduced by the design of its portable shelter, yet a flexibility of choice is involved, for I’ve watched them “decide” which of two tiny grains to choose. It is always the right one to fit the empty space.
Caddisfly larvae living on stream bottoms build a variety of tubular, dome-shaped, or pyramidal cases, each according to its kind. Some are made of tiny, pre-cut sticks or small pieces of bark held together with silk spun from glands in the larva’s head. One uses a long stick at the end of its case to serve as a fixed rudder, keeping the animal facing upstream.
A stone-house caddis larva selects small pebbles, with the largest cemented along each side of a tubular case to provide ballast. The weighted house protects against predators and prevents the insect from being swept downstream. Where water is swiftest, one species of caddis larva cements a streamlined sand-grain shelter onto a large rock. Another builds a sloppy house under a rock, but makes up for the sloppiness by weaving a perfect fishnet suspended between its home rock and an adjacent one. The meshes of the net are absolutely square, and should the net be ripped, the larva repairs it at once. When organic matter carried downstream is lodged in the net, the owner emerges to sweep it clean, enjoying a good meal in the process.
It’s not just the aquatic insects that are efficient builders. The larva of the evergreen bagworm moth constructs and carries around a spindle-shaped case of webbing, the outside of which is camouflaged and strengthened with small twigs, bits of leaves, and bark. As the larva grows, its portable case increases in size until pupating is imminent, at which time the case is suspended from a twig with silk. After adults develop, the wingless female remains in her house, emitting pheromones to attract heavy-bodied males that fly in on translucent wings, their scales lost upon emergence from the larval case.
Hung between branches, a familiar orb web glistens with early morning dew. Its suspending radial strands are strong, but not sticky, while the spiralones are weaker, with evenly spaced droplets of sticky mucilage. The spider waits in the center. An orb web shares with drumheads and loudspeakers a common engineering design: it is a diaphragm. A diaphragm is supported around its periphery, but it is free to vibrate in the center.
When an insect flies into an orb web, the entire structure vibrates most vigorously in the center where the spider waits, even if the fly or moth is stuck out near the edge. Some of the spider’s eight legs rest on the strong radial strands that telegraph the direction from which the struggling insect is attempting to free itself. The spider runs out, pounces, and deftly wraps its victim in swathes of silk while injecting paralyzing venom. If it doesn’t feed right away, the spider has a fresh meal waiting later. An orb web is based upon recognized engineering principles yet is created by a creature we tend to dismiss.
Pond water under a microscope may reveal a tapered tube composed of ruby-red pellets. From inside the wide end of the tube, a pair of flaps extend, each equipped with tiny beating hairs that create a vortex drawing food toward a rotifer’s mouth. The animal constructs its house by making bricks. It selects debris and places it in a special pouch under its head to be mixed with a glandular secretion. It then cements each of the bullet-shaped pellets in place as it builds a tube, row upon meticulous row, each a trifle larger than the one before, because the tube must widen to allow for the rotifer’s growth. As a mason, it practices its craft flawlessly.
Natura maxime miranda in minimis, wrote Hieronymus Fabricius, a Renaissance anatomist, “Nature is most wonderful in little things.”