Kids Research Express

Coral, small, sedentary marine animal, related to the sea anemone but characterized by a skeleton of horny or calcareous material. The skeleton itself is also called coral. Although most corals form colonies by budding, there are some solitary corals; in both types the individual animals, called polyps, resemble the sea anemone in form. Corals grow in warm and temperate climates and in the cold water found at greater depths, but they are most abundant in warm, shallow water; over 200 coral species are found in the Great Barrier Reef of Australia. In many shallow-water species the polyps contain unicellular plants, which may provide the high oxygen concentration required by such corals. Stony Corals  In the large group known as stony corals, or true corals (Madreporaria), each polyp secretes a cup-shaped skeleton, the theca, around itself. Some solitary corals of that group may reach a diameter of 10 in. (25 cm); in the colonial forms the individual polyps are usually und...

The largest of the green algae, Ulva (sea lettuce), grows to a ribbon or sheet 3 ft (91 cm) long. It provides food for many sea creatures, and its broad surface releases a large amount of oxygen. Fucus, called rockweed or bladderwrack, is a tough, leathery brown alga (though it often looks olive-green) that clings to rocks and has flattened, branched fronds buoyed by air bladders at the tips. Seaweeds , especially species of the red algae Porphyra (nori) and Chondrus, form an important part of the diet and are farmed for food in China and Japan; other species (often called laver) are eaten in the British Isles and Iceland. Commercial agar (vegetable gelatin) is obtained from species of red algae and is the most valuable seaweed product. Irish moss or carrageen (Chondrus crispus), a red alga, is one of the few seaweeds used commercially in the United States. After being bleached in the sun the fronds contain a high proportion of gelatin, which is used for cooking, textile sizing, m...

Seaweed, name commonly used for the multicellular marine algae. Simpler forms, consisting of one cell (e.g., the diatom) or of a few cells, are not generally called seaweeds; these tiny plants help to make up plankton. The more highly developed types of seaweed usually have a basal disk, called a holdfast, and a frond of varying length and shape, which often resembles a plant in having stemlike and leaflike parts. Types of Seaweed The simplest of the seaweeds are among the cyanobacteria, formerly called the blue-green algae, and green algae (division Chlorophyta), found nearest the shore in shallow waters and usually growing as threadlike filaments, irregular sheets, or branching fronds. The brown algae (division Phaeophyta), in which brown pigment masks the green of the chlorophyll, are the most numerous of the seaweeds of temperate and polar regions. They grow at depths of 50 to 75 ft (15–23 m). The red seaweeds (division Rhodophyta), many of them delicate and fernlike, are found...

Symbiosis, the habitual living together of organisms of different species. The term is usually restricted to a dependent relationship that is beneficial to both participants (also called mutualism) but may be extended to include parasitism, in which the parasite depends upon and is injurious to its host; commensalism, an independent and mutually beneficial relationship; and helotism, a master-slave relationship found among social animals (e.g., the ant and the aphid). True symbiosis is illustrated by the relationship of herbivorous animals (e.g., cockroaches, termites, cows, and rabbits) to the cellulose-digesting protozoans or bacteria that live in their intestines; neither organism could survive without the other. Other symbiotic relationships include the interdependence of the alga and the fungus that form a lichen and the relationship between leguminous plants and the nitrogen-fixing bacteria, which is important in agriculture. Two obvious examples of a plant-to-animal relationshi...

Peat Moss, also called sphagnum moss and bog moss, common name for about 300 species of moss plants that grow in swamps and bogs throughout the world. Peat moss may grow to 30 cm (12 in) or more in height. The plants have many branches covered with small, light green leaves. The leaves and stems have special cells that absorb and hold much water. Peat moss is one of the most common plants from which peat, a fuel, is produced. When the plants die, the dead organic matter is preserved more or less intact because the moss is acidic, so bacterial and fungal decay occurs slowly. The dead peat moss and other plants are compressed by the weight of the living plants growing above them. This compressed matter eventually forms the peat. The peat can be cut into blocks and removed for use as fuel. Peat moss is also useful in gardening. It combats excessive alkalinity in the soil and produces the acid environment that certain plants need to grow, including such ornamental shrubs as rhododendro...

A small bryophyte plants belonging to the phylum Anthocerophyta; any of several submerged plants of the genus Ceratophyllum, forming branched masses in quiet water and having finely dissected, whorled leaves and minute unisexual flowers.  Unlike liverworts but like mosses, hornwort sporophytes have stomata. The hornwort gametophyte consists of a low thallus, out of which numerous slender, upright sporophytes tipped with sporangia grow. The sporophyte has a meristem that elongates the sporophyte with new growth, a feature that distinguishes the plant from the other bryophytes. The name of the hornworts was suggested by the hornlike appearance of the sporophytes.

Calabash Tree (Crescentia cujete) of the trumpet-creeper family (Bignoniaceae), 6 to 12 metres (20 to 40 feet) tall, that grows in Central and South America, the West Indies, and extreme southern Florida. It is often grown as an ornamental. It produces large spherical fruits, up to 50 cm (20 inches) in diameter, the hard shells of which are useful as bowls, cups, and other water containers when hollowed out. The fruit's shell encloses a whitish pulp and thin, dark brown seeds. The tree bears funnel-shaped, light green and purple-streaked flowers and evergreen leaves. Fruits of the unrelated bottle gourd (Lagenaria siceraria) are also known as calabashes. In some countries the rind and juice are used for medicinal purposes.