Broad Sea Fan

Eunicella verrucosa

The sea fan is a type of coral made up of many simple polyps joined together to form a colony in a fanlike pattern. In common with a number of other marine invertebrates, sea fans are beautiful and often form major attractions in “submarine gardens.” A slow growing animal, it is now under threat from overcollection. Sea fans are found in most of the world’s seas and oceans. They may grow from shallow water down to the edge of the continental shelves and beyond; they are even found at depths of about 13,000 feet (4,000 m) in some parts of the world. The broad sea fan occurs in the northeastern [Read more]

General features ( insects )

In numbers of species and individuals and in adaptability and wide distribution, insects are perhaps the most eminently successful of all animals. They dominate the present-day land fauna; about 800,000 species have been described, representing about three-fourths of known animal life the actual number of living species could range from 5,000,000 to 10,000,000, entomologists estimate. The orders that contain the greatest numbers of species are Coleoptera (beetles), Lepidoptera (butterflies and moths), Hymenoptera (ants, bees, wasps), and Diptera (true flies). [Read more]

Importance ( insects )

Role in nature

Insects play many important roles in the economy of nature. They aid bacteria, fungi, and other organisms in the decomposition of organic matter and in soil formation. The decay of carrion, for example, brought about mainly by bacteria, is accelerated by the maggots of flesh flies and blowflies. The activities of these larvae, which distribute and consume bacteria, are followed by those of moths and beetles, which break down hair and feathers. Insects and flowers have evolved together. Many plants depend on insects for pollination. Some insects are predators of others. [Read more]

Form and function ( insects )

Cuticle

The insect is covered by the cuticle, a layer of inert material laid down by a single sheet of epidermal cells. It consists mainly of chitin, a carbohydrate also known as polyacetylglucosamine, and sclerotin, a hard substance composed of protein tanned by quinones. The cuticle, which has a superficial layer of waterproofing wax to prevent loss of water by evaporation, also serves as the skeleton to which the muscles are attached. In insects (e.g., caterpillars), in which the cuticle is soft and flexible, the skeleton is of the hydrostatic type; that is, body fluid pressure, maintained by muscle tension beneath the body wall, provides the firmness necessary for the function of muscles involved in [Read more]

Evolution and paleontology ( insect )

Origin of insects

The most primitive insects known are found as fossils in rocks of the Middle Devonian Period and lived about 350,000,000 years ago. The bodies of those insects were divided then, as now, into a head bearing one pair of antennae, a thorax with three pairs of legs, and a segmented abdomen. Those insects originated with the terrestrial branch of the phylum Arthropoda. The Arthropoda, whose origin is thus far unknown, probably arose in Precambrian times, perhaps as much as 1,000,000,000 years ago. Some arthropods colonized the open sea and have become the present-day class Crustacea (crabs, shrimps) and the now-extinct Trilobita. Other arthropods colonized the land. This terrestrial line [Read more]

Ant

any member of the approximately 8,000 species of the insect family Formicidae (order Hymenoptera). Ants occur worldwide but are especially common in hot climates. All ants are social in habit; i.e., they live together in organized colonies, and they range in size from 2 to about 25 millimetres (about 0.08 to 1 inch). Their colour is usually yellow, brown, red, or black. A few genera (e.g., Pheidole of North America) have a metallic lustre. Typically, an ant has a large head and a slender, oval abdomen joined to the thorax, or midsection, by a small waist. The antennae are elbowed. The mouth has two sets of jaws: the outer pair is used for carrying objects such as food and for digging, and the inner pair is used for chewing. Some species have a powerful sting at the tip of the abdomen. There are [Read more]

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