I. Introduction 
II. Seahorses: Unique Creatures Threatened by Habitat Loss and Overfishing
III. Octopuses, Squids, Cuttlefishes, and Nautilus: The Fascinating World of Cephalopods
IV. Declining Amphibian Populations
V. El Salvador's Biological Diversity
VI. Great Quote from Père Armand David
VII. River Dolphins: 'Magical' Creatures Faced with an Uncertain Future
VIII. Biodiversity Web Pages
IX. Biodiversity References

    Biodiversity refers to the incredible variety of life found in our planet. In the book Biodiversity II, Edward O. Wilson defines biodiversity as: "all hereditarily based variations at all levels of organization, from the genes within a single local population or species, to the species composing all or part of a local community, and finally to the communities themselves that compose the living parts of the multifarious ecosystems of the world." Life on earth is so diverse that we really have no idea how many species there are. Estimates range between 5 million and 30 million, but some biologists believe the figure may be as high as 100 million. Biodiversity is central to our existence. We derive much of the food we eat from species that were once wild, and we continue to rely on wild species to genetically improve domestic varieties of corn, tomatoes, and other food staples. We also use plants and animals found in natural ecosystems to develop new drugs for the treatment of various diseases. In addition, biodiversity provides us with many ammenities, such as bird-watching, ecotourism, fishing, and others. Despite the value of biodiversity to humans, we are currently destroying natural ecosystems at such a rate that many biologists fear that in a few decades we will cause an unprecedented number of extinctions. We are so far from cataloguing the diversity of life on Earth that an unknown number of animals and plants will become extinct and we'll never know what we lost. This is especially true of tropical forests and coral reefs, which we are losing particularly fast. These ecosystems are mostly in developing countries, which face many important challenges related to high debt burdens, poverty, social inequality, and population growth. Despite the grim outlook in some areas, there are many ongoing efforts to help preserve our natural heritage. Below you will find essays related to biodiversity, links to web sites with lots of information about what you can do to help save biodiversity, and some really good references if you want to read more about this subject.

    Seahorses are small fish that inhabit shallow temperate and tropical waters along coastal ecosystems throughout the world's oceans. They are unique in many ways. Their appearance is so different from that of other fish that people long ago believed they were insects. Instead of what we normally think of as fish, these creatures look like an amalgamam of parts from different species of animals. Their head resembles that of a miniature horse. Their small, delicate fins remind us of fish. They also have long, prehensile tails that seem out of place in a fish. Despite such odd combinations, seahorses are among nature's most beautiful creations. They look like ornaments in their coral reef, seagrass and mangrove habitats. They are also unique because in seahorses it is the male rather than the female who becomes pregnant. Seahorses are also totally monogamous. Unfortunately, seahorses are threatened by habitat loss and overfishing.

Octopuses, Squids, Cuttlefishes, and Nautiluses: The Fascinating
World of Cephalopods

    There are about 700 species of cephalopods throughout the world's oceans. Octopuses and squids are the best known, but the group also includes cuttlefishes and nautiluses. Cephalopods, like oysters and clams, are mollusks. What sets them apart from other mollusks is the absence or internalization of an outer shell in most species, and the development of a mantle for rapid jet-propelled locomotion. They are aquatic creatures and can only survive out of the water for about an hour. Cephalopods vary greatly in size. The smallest is Idiosepius, which measures 8 mm long. The largest is the giant squid, Architeuthis, which has the distinction of being the largest invertebrate in the world and one of the largest marine animals. Giant squids can attain lengths of over 18 meters and weigh over 1,000 kilograms. Cephalopods have developed a number of remarkable adaptations to help them survive. Their ability to change color and reproduce patterns in their environment surpasses that of chameleons. Some species can produce biological light in order to hide from predators and communicate in the deep seas. And squids are able to deploy their long tentacles faster than a preying mantis can use its forelimbs.

  Declining Amphibian Populations

    Amphibians are a very diverse group of vertebrates that live on every continent except Antarctica. Since the mid-1970s drastic population declines of many amphibian species have been recorded. These include mass die-offs and the appearance of large numbers of amphibians with deformities. Such events have been recorded in many localities around the world, including pristine natural habitats. Some species, such as the golden toad in Costa Rica, are believed extinct. Although the causes of these population declines are poorly understood many scientists believe that a number of factors, many of which may be interrelated, are responsible. Among the most common causes listed in the literature are climate change, increased exposure to ultraviolet radiation, new pathogens, introduced species, habitat destruction and modification, acid rain, and toxic substances. Because amphibians have a biphasic life in both water and land, and have permeable skins, they are considered to be good environmental indicators. As such, declining amphibian populations are seen by many as a sign of deteriorating environmental quality.

El Salvador's Biological Diversity

    El Salvador is a small country in Central America. With an area of 20,746 km2, it is roughly the size of New Jersey or Massachusetts. Despite it's small size it has a rich biological diversity. There are more species of trees there than in all of Western Europe. It also has more butterfly species than the 48 contiguous states of the United States. Preliminary inventories of the country indicate there is an overwhelming biological diversity: over 500 species of birds, almost 1,000 species of butterflies, over 400 species of orchids, over 800 species of trees, and over 800 species of marine fish.

    El Salvador has a marked rainy season that lasts between May and October. Much of the vegetation is deciduous, and many trees lose their leaves in the dry season. However, in the higher elevations there is enough humidity so that most trees maintain their leaf cover throughout the year. The climate and soil types found in El Salvador suggest that the country was originally covered almost completely by forests. In addition, the mountainous and volcanic geography of the country resulted in a large diversity of natural habitats. It's altitudinal range is from sea level to its highest peak at an elevation of 2,730 meters. Among the many habitats found in the country are mangrove forests, swamp forests, tropical dry forests, freshwater lagoons, pine and oak-pine forests, and cloud forests.

    Today natural forest cover has been drastically reduced. Some habitats, such as mangrove forests, are still fairly well represented, with about 40% of the original cover still remaining. Other types of habitat have been practically wiped out. About 17% of the country's area is covered by forests, though most of this area consists of secondary forest and scrubland. An additional 9% is covered by coffee plantations, which are covered with trees to provide shade for coffee bushes. Only about 3% of the country is covered by primary natural forests, and the area protected by national parks is only about 0.5% of the country's total area.

    "This Cosmos, so marvelous to those with eyes to see, is reduced to dullness by a blind and egotistical preoccupation with material things. Soon the horse and pig on the one hand, and wheat and potatoes on the other, will replace all these hundreds, these thousands of creatures - animal and vegetable - that God has created to live among us....They have the right to life and we annihilate them and brutally make existence impossible for them....It is unbelievable that the Creator could have placed so many diverse organisms on the earth, each one so admirable in its sphere, so perfect in its role, only to permit man, his masterpiece, to destroy them forever."

River Dolphins: 'Magical' Creatures Faced with an Uncertain Future

            In the book Jacques Cousteaus's Amazon Journey, a member of Cousteau's expedition team describes the boto, a species of river dolphin that inhabits the Amazon, as: "A pink dolphin that hunts through the woods with the dexterity of a jungle cat!" In the Ganges river, India, susus, another species of river dolphin, are sometimes seen swimming on their sides. As they swim, their heads sweep up and down in a scanning motion, using echolocation to track their prey, and tracing the bottom of the river with their flippers. In China, the baiji, a river dolphin that lives in the Yangtze river, has historically been regarded as a mythical creature. Some believe them to be the reincarnation of a beautiful princess. Given their unusual physical characteristics and the folklore that's been created around them it is easy to understand why river dolphins are often regarded as 'magical' or 'supernatural' creatures.

        Unfortunately, river dolphins face a very uncertain future. Two species, the baiji, in China, and the bhulan, in Pakistan, are among the rarest mammals in the world. Recently, Discover magazine listed the baiji as one of 20 species of animals we may lose in the next twenty years. The outlook for these two species seems dismal. According to Richard Garstang, a conservation adviser at WWF-Pakistan, an organization that is involved with bhulan conservation efforts, "The Threat is very real. The population could crash at any time." About the baiji, Robert Brownell, chief of the marine mammal division of the Southwest Fisheries Science Center in La Jolla, California, considers that, "Based on what we know, it doesn't look like this dolphin is going to make it." 

    If you want to read more about biodiversity, and about some remarkable efforts being carried out to preserve our natural heritage, visit the following web sites:
 

•       Instituto Nacional de Biodiversidad (INBio)

 
•       All Species Foundation

•       DIVERSITAS - An International Programme of Biodiversity Science

 
•       Species 2000

 
•       Global Biodiversity Information Facility

 
•       SalvaNATURA

•       Mesoamerican Trail Project

•       World Conservation Monitoring Centre

•       World Wildlife Fund

•       Conservation International

•       The Nature Conservancy

•       Wildlife Conservation Society

•       Smithsonian Institution

•       The World Conservation Union (IUCN)

•       World Resources Institute (WRI)

•       Inter-American Biodiversity Information Network

•       Biodiversity Support Program

•       Center for Marine Conservation

•       World Rainforest Information Portal

•       BirdLife International

    If you want to read some great books and articles about biodiversity, here are some suggestions you can take to your local library or bookstore:

• Cracraft, Joel, and Francesca T. Grifo, eds. 1999. The Living Planet in Crisis: Biodiversity Science and  Policy. New York: Columbia University Press.
• Eldredge, Niles. 1998. Life in the Balance: Humanity and the Biodiversity Crisis. Princeton, N.J.: Princeton University Press.
• Guruswamy, L. D. and J. A. McNeely. 1998. Protection of Global Biodiversity Converging Strategies. Durham: Duke University Press.
• Leakey, Richard, and Roger Lewin. 1995. The Sixth Extinction: Patterns of Life and the Future of Humankind. New York: Doubleday.
• Mace, Georgina M., Andrew Balmford and Joshua R. Ginsberg. 1998. Conservation in a Changing World. New York: Cambridge University Press.
• Mittermeier, R. A., N. Myers and C. G. Mittermeier. 2000. Hotspots: Earth's Biologically Richest and Most Endangered Terrestrial Ecoregions. Chicago: University of Chicago Press.
• McNeely, J. A., K. R. Miller, W. V. Reid, R. A. Mittermeier and T. B. Werner. 1990. Conserving the World's Biological Diversity. Washington, D.C.: The World Bank, World Resources Institute, IUCN, Conservation International, and World Wildlife Fund.
• Myers, Norman et al, 2000. "Biodiversity hotspots for conservation priorities," Nature, Vol. 403, 24 February, pages 853-858.
• Pimm, Stuart L. and Peter Raven, 2000. "Extinction by numbers," Nature, Vol. 403, 24 February, pages 843-845.
• Poiani, Karen A. et al, "Biodiversity Conservation at Multiple Scales: Functional Sites, Landscapes, and Networks," BioScience, Vol. 50, No. 2, February 2000, pages 133-146.
• Quammen, David. 1996. The Song of the Dodo: Island Biogeography in an Age of Extinctions . New York: Simon and Schuster.
• Reaka-Kudla, Marjorie L., Don E. Wilson and Edward O. Wilson (editors). 1996. Biodiversity II . Washington, D.C.: Joseph Henry Press.
• Sala, Osvaldo E. et al. 2000. "Global Biodiversity Scenarios for the Year 2100," Science, Vol. 287, 10 March, pages 1770-1774.
• Wilson, E. O. and F. M. Peters, eds. 1988. Biodiversity. Washington, D.C.: National Academy Press.
• Wilson, E. O. 1992. The Diversity of Life. Cambridge, Mass.: Harvard University Press.