Botkin Environmental Science Earth as Living Planet 8th txtbk

148 CHAPTER 8 Biological Diversity and Biological Invasions
Table 8.1 NUMBER OF SPECIES BY MAJOR FORMS OF LIFE AND BY NUMBER OF ANIMAL SPECIES
(FOR A DETAILED LIST OF SPECIES BY TAXONOMIC GROUP, SEE APPENDIX.)
A. NUMBER OF SPECIES BY MAJOR FORMS OF LIFE
ESTIMATED NUMBER
LIFE-FORM EXAMPLE MINIMUM MAXIMUM
Monera/Bacteria Bacteria 4,800 10,000
Fungi Yeast 71,760 116,260
Lichens Old man’s beard 13,500 13,500
Prostista/Protoctist Ameba 80,710 194,760
Plantae Maple tree 478,365 529,705
Animalia Honeybee 873,084 1,870,019
Total 1,522,219 2,734,244
B. NUMBER OF ANIMAL SPECIES
ANIMALS
Insecta Honeybees 668,050 1,060,550
Chondrichthyes Sharks, rays, etc. 750 850
Osteichthyes Bony fish 20,000 30,000
Amphibia Amphibians 200 4,800
Reptilia Reptiles 5,000 7,000
Aves Birds 8,600 9,000
Mammalia Mammals 4,000 5,000
Animal total Total 873,084 1,870,019
fossil record and studies in molecular biology suggest
that it may be more appropriate to describe life as existing
in three major domains, one called Eukaryota or
FIGURE 8.5 The barefaced bulbul, discovered in Laos in 2009,
shows us once again that there are still species of animals and plants
unknown to science.
Eukarya, which includes animals, plants, fungi, and
protists (mostly single-celled organisms); Bacteria; and
Archaea. 3 As you learned in Chapter 6, Eukarya cells
include a nucleus and other small, organized features
called organelles; Bacteria and Archaea do not. (Archaea
used to be classified among Bacteria, but they have substantial
molecular differences that suggest ancient divergence
in heritage—see Chapter 6, Figure 6.7.)
The plant kingdom is made up of divisions, whereas
the animal kingdom is made up of phyla (singular: phylum).
A phylum or division is, in turn, made up of classes,
which are made up of orders, which are made up of families,
which are made up of genera (singular: genus), which
are made up of species.
Some argue that the most important thing about biological
diversity is the total number of species, and that
the primary goal of biological conservation should be to
maintain that number at its current known maximum. An
interesting and important point to take away from Table
8.1 is that most of the species on Earth are insects (somewhere
between 668,000 and more than 1 million) and