|PREHISTORIC LIFE HOME||PREHISTORIC LIFE TABLE OF CONTENTS||OBL HOME||OBL REFERENCES|
NUMBERS OF SPECIES:
There are about 1.5 million species which are known to exist on earth. The number of as yet undescribed species is probably greater than the number already known to exist. Here are the statistics on the known number of species according to the biological group.
1) Bacteria: 4,800 sp.
--sponges: 5,000 --corals & jellyfish: 9,000
--various worms: 36,200 --molluscs: 50,000
--starfish & relatives: 6,100
--arthropods other than insects: 123,400
--It is estimated that the number of undiscovered species of insects exceeds the total number of species of all organisms.
--fish: 25,000 --amphibians: 4,000
--reptiles: 6,500 --birds: 8,500 --mammals: 4,000
-There are even new species of mammals that continue to be discovered: 1988-90 3 sp. of primates discovered; 1991 a new whale sp. was identified (and another sp. has been sighted but not yet identified); a new sp. of Vietnamese deer was discovered in 1995.
Why are there so many types of species? One
reason is that the types of environments differ in different parts of
the world. Even in one region
of a single continent, southern
|the thorn forest-scrubland of the
|the coastal environments of
|and subtropical rainforests.|
|The aquatic environments
|have very different species than the those found in the aquatic
Throughout the world, there are classes of ecosystems referred to as biomes. A biome is a major type of physical environment that is inhabited by characteristic plants and animals. Temperature and annual precipitation determine the nature of many of these biomes.
a) deserts: Deserts actually contain a diversity of organisms. Some are dormant until the rains come and others are nocturnal.
b) grasslands: In grasslands, the amount of rainfall is less than that needed to support trees. Herbivorous mammals and the insects they attract are important components of the animal life.
c) savanna: Savannas are extensive grasslands with occasional trees. They are often tropical with rainy and dry seasons.
d) tropical rain forests: Tropical rainforests have high temperatures and a great
amount of annual rainfall. There
is little seasonal change and, as a result, trees do not drop their leaves.
Because the trees do not drop their leaves and because insects
and decomposers quickly make use of the organic matter on the forest floor,
the soils are relatively poor with very few nutrients.
Tropical rainforests have an incredible biodiversity—an estimated
half of all the plant and animal species on earth live here.
The following images are of a Brazilian rainforest (just south
|e) temperate deciduous forests: The dominant type of tree in temperate deciduous forests are the broad-leafed flowering plants which drop their leaves in colder seasons. There is a lesser diversity of species than that found in tropical rainforests.|
|f) coniferous forests: Conifers have thin leaves (which we often call needles).
These needles allow them to lose less water which is especially an
advantage in areas with harsh winters such as northern latitudes and higher
altitudes (as in
|g) tundra: The tundra has a permanently
frozen soil layer and short plants. It
can be found in polar regions and at high altitudes
(such as in the
While some organisms are generalists, adapted to survive under a variety of conditions with a variety of food sources, many are specialists--they are adapted to a narrow set of conditions. Sea lions only inhabit certain coastal regions of the world.
|These macaws are native
to tropical forests of the
|The tagua (collared peccary) is the largest wild pig in the world
and exists only in an arid region of central
|Most of the earth’s organisms only inhabit very restricted regions of the planet. The following maps depict the restricted habitats of a variety of species.|
A) Because biomes vary across the world or across the country, one finds many organisms occurring only in certain areas:
1) the east coast: great black-backed gull, surf & white-winged scoters, black-bellied plover, purple sandpiper, Louisiana heron, white ibis, glossy ibis, tufted duck, whistling swan, red-necked grebe,
2) the Northeast: chestnut-sided warbler, golden-winged warbler, alder flycatcher, magnolia warbler, black-throated green warbler, blackburnian warbler, black-throated blue warbler
3) grasslands: greater prairie chicken, gray partridge, lark bunting, chestnut-collared, McCown's, & Smith's longspurs,
4) Fla:brown noddy, black noddy, magnificent frigatebird, swallow-tailed kite (Georgia also), wood stork, great white heron, limpkin, short-tailed hawk, everglade kite, spotted-breasted oriole, gray kingbird, blue-gray tanager, black-whiskered vireo, mangrove cuckoo, red-whiskered bulbul, smooth billed ani
5) Texas:whooping crane (50 individuals), least grebe, green kingfisher, white tailed hawk, black-capped vireo, jacana, scaled quail, chachalaca, pauraque, white-winged dove, cave swallow, golden-fronted woodpecker, black-headed oriole, kiskadee flycatcher, yellow green vireo, black-crested titmouse, buff-bellied hummingbird
6) New England: common eider, mourning warbler, spruce grouse, hawk owl, boreal owl, bay-breasted warbler, yellow throated flycatcher, gray-cheeked thrush, boreal chickadee, blackpoll warbler
About one quarter of the earth’s mammals and reptiles, 21% of amphibians, 30% of fish, and 12% of the earth’s birds are in danger of extinction. The loss of habitat is the greatest threat to 85% of the earth’s most threatened birds. About 1/3 of parrot species are endangered by habitat loss and collecting for pets or plumage.
Many populations now exist in such small
numbers that they are in danger of extinction.
Some occur in
I) MANY ENDANGERED SPECIES ARE FOUND ONLY IN CERTAIN PARTS OF THE WORLD
The maps above depicted the limited distribution of many species globally.
MANY OF THE ENDANGERED ORGANISMS FOUND IN THE
--Key Deer: FL
--Jaguarundi: one subspecies TX, the other AR
--Hawaiian Hoary Bat: HI
--Mariana Fruit Bat:
--6 species of Kangaroo
--Puerto Rican parrot,
Puerto Rican nightjar, Puerto Rican plain pigeon:
--Northern Spotted Owl: CA, OR, WA
--Atwaters Greater Prairie Chicken: TX
--Cactus ferrugineous Pygmy Owl: AZ
--Bluetail Skink, Sand
Skink, Atlantic Saltwater Marsh Snake:
Giant Garter Snake:
--Concho Water Snake: TX
--Yellow Blotched Map Turtle: MS
--Barton Springs Salamander: TX
--Red Hills Salamander:
--Shenandoah Salamander: VA
--Puerto Rican Crested
--Pygmy and Smoky Madtom: TN
--Pahrump Poolfish, Devils Hole and Ash Meadows Pupfish: NV
--Comanche Springs Pupfish: CA
--Chum Salmon: VA
--Coho Salmon: CA
--Pygmy Sculpin and
--Little Coloroado Spinedace: AZ
--Steelhead: OR, WA
--June Sucker: UT
--Warner Sucker: OR
--Greenback Trout: CO
6) INVERTEBRATES (Spiders and Clams as examples)
--Spruce-fir Moss Spider: NC, TN
--Brittons Beargrass, Amargosa Niterwort, White Birds in a Nest: FL
--Mohrs Barbaras Buttons: AL & GA
--a great diversity
of plants native to
--Macfarlanes : ID, OR
--Fassets Locoweed: WI
--Brady Pincushion Cactus:AZ
--Peebles Navajo Cactus
--Blowout Penstemon: NE
--Penland Beardtongue: CO
--Godfrey’s Butterwort: FL
LOSS OF HABITAT
|The above land in
This beautiful region
Even in this region, the original habitat
has disappeared. Although the
following pictures depict forests of the