Browse "Nature & Geography"

Displaying 721-740 of 900 results
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Sea Otter

Sea Otter (Enhydra lutris), largest and most marine weasel, lives exclusively in shallow seas of the N Pacific, formerly from Japan to California.

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Sea Urchin

Sea Urchin, radially symmetrical marine invertebrate. Sea urchins and near relatives, the sand dollars and heart urchins, belong to class Echinoidea of phylum Echinodermata.

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Seabird

Seabirds are those bird species which spend long periods away from land and obtain all or most of their food from the sea while flying, swimming or diving, and occupy all of the world's oceans.

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Seal

Seal is a common name given to a diverse group of aquatic, generally marine mammals of the order Pinnipedia.

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Seashell

Shell is a hard covering made primarily of calcium carbonate, secreted by invertebrate animals (eg, molluscs, barnacles, sea urchins).

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Seaweeds

Seaweeds are multicellular marine algae, visible to the naked eye. They extend from the uppermost reaches of sea spray on the shore to the lower limits of light beneath the surface of the water.

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Sedge

Sedge is a grasslike plant common throughout temperate and cold regions. The genus name, Carex (family Cyperaceae), is probably derived from keiro, referring to the sharp leaf margins.

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Sedimentary Rock

 Only about 5% of the Earth's crust is composed of sedimentary rocks, but they cover 70-75% of the exposed surface and contain many economically important minerals, as well as coal and petroleum.

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Seed Plants

The common feature uniting seed plants is the "seed habit," a unique method of sexual reproduction. In all vascular plants, the conspicuous plant is a spore producer (sporophyte) that alternates, in the life cycle, with a sexual phase (gametophyte).

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Shark

A shark is a marine fish with cartilaginous skeleton belonging to subclass Elasmobranchii, class Chondrichthyes, order Pleurotremata.

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Shearwater

The shearwater (order Procellariiformes, family Procellariidae) is a medium-sized seabird.

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Shrew

Shrew (Soricidae), family of small insectivores represented today by approximately 250 species worldwide, 16 in Canada.

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Shrike

Shrike is the common name for the family Laniidae of singing birds.

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Shrimp

Shrimp are decapods ("10-footed") crustacean, differing from other decapods in being adapted for swimming, a fact reflected in the large, laterally compressed abdomen and well-developed pairs of swimming legs.

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Silica

Silica, or silicon dioxide (SiO2), occurs as the MINERAL quartz and is the most abundant mineral of the Earth's crust. It also occurs in the skeletal parts of some animals (eg, certain protozoa) and various plants.

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Silver

Important producing countries now are Mexico, Peru, the Commonwealth of Independent States, the US, Canada, Australia, Chile, Poland and China. Photographic films and papers account for about 25% of the demand for silver.

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Silviculture

Silviculture is the branch of FORESTRY that deals with establishing, caring for and reproducing stands of trees for a variety of forest uses including wildlife habitat, timber production and outdoor recreation.

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Skunk

 The skunk is a carnivorous, cat-sized mammal. Skunks were previously considered as part of the weasel family (Mustelidae) but DNA research has placed them in their own family, Mephitidae.

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Sky

The sky appears its deepest blue when the air is dry and clean. Water vapour and dust scatter all colours of light, causing the blue to appear washed-out and pale.