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Expert-reviewed information about the Earth.  For everyone.

 

 

  • Marine microbes Featured Article Marine microbes Marine microbes

    The term 'Marine microbes' encompasses all microscopic organisms generally found in saltwater. Most micro-organisms are acellular and fall into the major categories of... More »

  • Selenium Featured Article Selenium Selenium

    Selenium is a gray, metallic element. Its atomic number is 34 and its symbol is Se. The Swedish scientist Jons Jacob Berzelius discovered selenium in 1817. In studying the... More »

  • Aquifer Featured Article Aquifer Aquifer

    Introduction An aquifer is a geologic formation, group of formations, or part of a formation that contains sufficient saturated permeable material to yield significant... More »

  • Frugivore Featured Article Frugivore Frugivore

    A frugivore is a type of herbivore (plant-eating animal) that eats a substantial portion of fruit.  A few frugivores species eat only fruit, but many also consume leaves... More »

  • Endangered species Featured Article Endangered species Endangered species

    An endangered species is a biological taxon that is at risk of becoming extinct in a proximate time frame much sooner than the long term horizon in which species typically... More »

  • Healthy Community Design Featured Article Healthy Community Design Healthy Community Design

    The way we design and build our communities can affect our physical and mental health. Healthy community design integrates evidence-based health strategies into community... More »

  • Carpenter bee Featured Article Carpenter bee Carpenter bee

    This hexapod (six-legged) insect is a bee in the subfamily Xylocoinae of either the genus Ceratina or Xylocopa that makes its nest in wood or plant stems. Along... More »

  • Limestone Featured Article Limestone Limestone

      Limestone  is a sedimentary rock whose chief mineral component is calcite (calcium carbonate: CaCO3). Limestone can be formed by precipitation of calcite... More »

  • Dugong Featured Article Dugong Dugong

    The Dugong, often referred to as the sea cow, is actually more closely related to elephants than to the bovine namesake.  Throughout much of their range, the Dugong has... More »

Recently Updated
Food Biodiversity Challenges From a Global Perspective Last Updated on 2014-07-25 14:03:15 Food collection or gathering has been an important part of human endeavors towards establishing civilization across the long history of human evolution. Humans have demonstrated their ingenuity in identifying and locating new and novel food sources located in their immediate surrounding and during their migration across the planet. Humans have become more successful than other species because of their better foraging abilities and coordinated group work in identifying and locating novel food sources over time. This trial and error approach has enabled humans over time to identify suitable food sources from their local environments. Over time, humans have identified more species that are edible or could be made edible using primitive to modern day recipes and cooking techniques. These long years of trial and errors have generated a wide range of food sources for... More »
Population-environment theory and contemporary applications Last Updated on 2014-07-24 15:49:49 Introduction Humans have sought to understand the relationship between population dynamics and the environment since the earliest times (1-3), but it was Thomas Malthus’ Essay on the Principle of Population in 1798 that is credited with launching the study of population and resources as a scientific topic of inquiry. Malthus’ famous hypothesis was that population numbers tend to grow exponentially while food production grows linearly, never quite keeping pace with population and thus resulting in natural “checks” (such as famine) to further growth. Although the subject was periodically taken up again in the ensuring decades, it wasn’t until the 1960s that significant research interest was rekindled. In 1963 the U.S. National Academy of Sciences published The Growth of World Population, a report that reflected scientific concern about the consequences of... More »
Northwestern Hawaiian Islands Marine National Monument Last Updated on 2014-07-23 19:37:23 The Northwestern Hawaiian Islands Marine National Monument is the single largest conservation area under the U.S. flag, and the largest marine conservation area in the world. It encompasses 137,792 square miles of the Pacific Ocean – an area larger than all the country's national parks combined. If they were laid atop the continental United States, the Northwest Hawaiian Islands (NWHI) would cover a distance equal to that between New York City and Omaha, or Boston and the Florida Everglades. The NWHI coral reefs are the foundation of an ecosystem that hosts more than 7,000 species, including marine mammals, fishes, sea turtles, birds, and invertebrates. Many are rare, threatened, or endangered. At least one quarter are endemic, found nowhere else on Earth. Many more remain unidentified or even unknown to science. Many of the islands and shallow water environments are... More »
Amphibian ecology and evolution Last Updated on 2014-07-23 18:38:53 Amphibians are found in ponds, streams, wetlands of all types, under rotten logs, in leaf litter, in trees, underground, even in pools of rain water inside large leaves. However, they are not able to osmoregulate in salt water and, therefore, are not found in the ocean. Although some amphibians defy the rules and thrive in cold or dry conditions, the group reaches its highest diversity and numbers in warm, humid climates.  In the wet tropics, amphibians remain active all year around, but in the temperate zone, winter temperatures cool their bodies, forcing them to become inactive. In the autumn, environmental cues direct amphibians to find moist, sheltered places like muddy pond bottoms or deep leaf litter to hibernate. The wood frog (Rana sylvatica) has the most northerly range of any amphibian, crossing the Arctic circle, into the Mackenzie River valley in the Northwest... More »
Brassicaceae: An agri-horticulturally important family Last Updated on 2014-07-22 17:19:27 Brassicaceae (Cruciferae) is an important dicotyledonous, angiospermic (true flowering) plant family with a global distribution. Species belonging to the Brassicaceae are well suited to a wide range of intensive and low input agri-techniques. They are primarily adapted to temperate and sub-tropical climates depending on the species. Brassica species play an important role in global agriculture and horticulture. The genus Brassica was described by Linneus in 1750 based on B. oleracea.  Brassica contains a number of important species and wide genetic diversity. The species are characterized by a wide range of adaptations that have been domesticated into crops including oilseed rape/canola and swede (Brassica napus L.); cabbage, cauliflower; broccoli, brussels sprout (B. oleracea L.); turnip, Chinese cabbage and pak choi (B. rapa L.) and mustards (B. nigra (L.) W.D.J. Koch, B. alba... More »