Chapter 15Classification

By Evil Mr. Bleecker

The Diversity of Life

The Diversity of Life

• How many species of organisms on earth?

but first.…

What’s a species?

Species• All individuals of a certain kind who are

able to interbreed

• Horses with horses, dogs with dogs, etc.

• Same number of chromosomes with similar shaped chromosomes

Species: Donkey x Horse

• Results in: a mule

• Therefore, are donkeys and horses the same species?

• but.... Mules are sterile...

How many species on Earth?

Surprisingly, we have a better understanding of how many stars there are in the galaxy than how many species there are on Earth. Estimates of global species diversity have varied from 2 million to 100 million species, with a best estimate of somewhere near 10 million. Only 1.4 million have actually been named. The problems stemming from the limits of current knowledge of species diversity are compounded by the lack of a central database or list of the world's species.

How to organize all this?

• In 1700’s Linnaeus developed a hierarchical classification system

• Originally, he divided all organisms into 2 Kingdoms:– Plants & Animals

• Then he subdivided each kingdom into progressively narrower groups:– Phylum, Class, Order, Family, Genus,

& species

Carl Linnaeus (1707-1778) also known as Carl von

Linné or Carolus Linnaeus, is often called the Father of Taxonomy. His system for naming, ranking, and classifying organisms is still in wide use today.

Classification System

• Kingdom• Phylum

• Class

• Order

• Family

• Genus

• species

Each and every species can now be classified by this system:

Five Kingdoms

Taxonomic Classification

• Kingdom-largest category. Includes all organisms that have one ore more common features.– The five common kingdoms:

• Monera

• Protists

• Fungi

• Plants

• animals

Microorganisms-organisms that can only be seen with a microscope.

Monera (bacteria and cyanobacteria)

• Single celled, microscopic prokaryotic organisms.

• Play vital role as decomposers, breaking down tissue of dead organisms into simpler compounds that serve as nutrients for bacteria and are eventually reused as nutrients by plants.

• Although bacteria can cause diseases in humans, not all bacteria are bad.

Monerans are Prokaryotic Cells

• Bacteria cells

• Surrounded by a membrane but have no distinct nucleus or other internal parts enclosed by membranes.

Protists (protista)

• Mostly single celled eukaryotic organisms.• Some cause human diseases such as malaria

and sleeping sickness.• Protists include: diatoms, dinoflagellates,

amoebas, golden brown and yellow-green algae, and protozoans.

Fungi

• Mostly many celled Mostly many celled eukaryotic organisms.eukaryotic organisms.

• Many are decomposers.Many are decomposers.• Some kill various plants Some kill various plants

and cause loss of crop and cause loss of crop and trees.and trees.

• Fungi include: Fungi include: mushrooms, molds, mushrooms, molds, mildews, and yeasts.mildews, and yeasts.

Plants (plantae)• Mostly many celled eukaryotic organisms.• Have

– Cell Walls of cellulose– Central water vacuole– Chloroplasts

Animals (animalia)• Many celled, eukaryotic organisms.

• Two types:

– Vertebrates-animals with backbones and a brain protected by skull bones (ex: fishes, amphibians, reptiles, birds, mammals)

– Invertebrates-have no spine (ex: sponges, jellyfish, worms, arthropods (insects, shrimp, spiders), mollusks (snails, clams, octopuses), echinoderms (sea urchins and sea stars)

Binomial System

• For ease of classification & recognition, we normally use only the last 2 names (Genus, species) to describe a species:

Homo sapiens

Pinus ponderosa

Escherichia coli

Gorilla gorilla

The Kingdoms of Life

Linnaeus created 2 Kingdoms

What’s missing?

Today it is common to use 6 Kingdoms

The 6 Kingdoms of Life

Animals

Plants

Fungi

Protists

Bacteria

Archaea Bacteria (ancient bacteria)