TAXONOMY INTRODUCTION

Assigning Scientific Names The first step in understanding and

studying diversity is to describe and name each species.

By using a scientific name, biologists can be sure that they are discussing the same organism. Common names can be confusing because they vary among languages and from place to place.

For example, the names cougar, puma, panther, and mountain lion can all be used to indicate the same animal— Felis Concolor.

Assigning Scientific Names In the eighteenth century, European scientists agreed to

assign Latin or Greek names to each species. Early scientific names often used long phrases to describe species in great detail.

For example, the English translation of the scientific name of a tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.”

It was also difficult to standardize names because different scientists focused on different characteristics

Binomial Nomenclature In the 1730s, Swedish

botanist Carolus Linnaeus developed a two-word naming system called binomial nomenclature.

The scientific name usually is Latin. It is written in italics. The first word begins with a capital letter, and the second word is lower cased.

Binomial Nomenclature The polar bear, for example, is

called Ursus maritimus.

The first part of the name—Ursus—is the genus to which the organism belongs. A genus is a group of similar species. The genus Ursus contains five other species of bears, including Ursus arctos, the brown bear or grizzly bear.

Binomial Nomenclature The second part of a scientific name—maritimus

for polar bears—is unique to each species and is often a description of the organism’s habitat or of an important trait. The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.

Binomial Nomenclature The scientific name of the red maple is Acer

rubrum.

The genus Acer consists of all maple trees.

The species rubrum describes the red maple’s color.

Classifying Species into Larger Groups

In addition to naming organisms, biologists try to organize, or classify, living and fossil species into larger groups that have biological meaning. Biologists often refer to these groups as taxa (singular: taxon).

The science of naming and grouping organisms is called systematics.

Linnaean Classification System Over time, Linnaeus’s original classification system

would expand to include seven hierarchical taxa: species, genus, family, order, class, phylum, and kingdom.

Problems With Traditional Classification

In a way, members of a species determine which organisms belong to that species by deciding with whom they mate and produce fertile offspring.

Ranks above the level of species, however, are determined by researchers who decide how to define and describe genera, families, orders, classes, phyla, and kingdoms.

Linnaeus grouped organisms into larger taxa according to overall similarities and differences. But which similarities and differences are the most important?

Problems With Traditional Classification

For example, adult barnacles and limpets live attached to rocks and have similar-looking shells.

Adult crabs don’t look anything like barnacles and limpets.

Based on these features, one would likely classify limpets and barnacles together and crabs in a different group. However, that would be wrong.

Modern classification schemes look beyond overall similarities and differences and group organisms based on evolutionary relationships and DNA analysis.

5 Kingdom system Traditionally, 5 kingdoms were

recognized: Anamalia Plantae Fungi Protista Monera

Domains Through molecular evidence, scientists

now classify all organisms into 3 domains.

Eukarya – nucleated celled organisms Animalia Plantae Fungi Protista

Bacteria – true bacteria Archaea – extreme bacteria

Bacteria Single cell without a nucleus Have a cell wall, cell membrane,

ribosomes, and DNA (not encased in a membrane).

Classified by their shape, cell wall composition, and how they get their nutrition.

Archaea Extreme bacteria Live in hot springs,

salt lakes, and other harsh environments.

Very different (in cellular processes) that other bacteria.

Protista Single cells with a

nucleus. Very diverse

kingdom. Includes animal

like protists (protozoans), plant like protists (algae), and fungal like protists (slime molds).

Fungi Multicellular (usually) and sessile (do not

move). Nutrition by absorption Includes mushrooms, molds, morels, and

yeast.

Plantae Multicellular, sessile, and autotrophic. Have cell walls made of cellulose. Have chloroplasts for photosynthesis. The word “division” is used in place of

phyla in plant biology.

Bryophyta Have no vessels to transport fluids. Absorb water through entire body (must

grow in a moist environment. No organs Have thin tubes called rhizoids for

anchorage. Classes include mosses liverworts and

hornworts.

Moss

Liverworts

Hornworts

Filicophyta Seedless and vascular Reproduces using spores. Ferns are an example.

Coniferophyta Cone baring plants (seeds are in cones) Gymnosperms – literally means “naked seed”

The ovule is exposed during fertilization Needle-like leaves These dominated the Mesozoic Era.

Coniferophyta

Anthophyta Flowering plants Angiosperms Dominant plant on Earth today. Broad Leaves

Anthophyta

Ginkophyta Common in the

Jurassic and Cretaceous.

One species remains (Ginko)

Male produces pollen, females produce unprotected ovules.

Animalia Multicellular Eukaryotic Heterotrophic Usually motile Often contain specialized tissue such as

muscle and nervous tissue.

Animal Bodies The bodies of most animals (all except

sponges) are made up of cells organized into tissues.

Each tissue is specialized to perform specific functions.

In most animals, tissues are organized into even more specialized organs.

Animal Numbers It is estimated that somewhere around 9

or 10 million species of animals inhabit the earth.

About 800,000 species have been identified.

These have been grouped into 36 separate phyla in the animal kingdom.

Porifera Contain numerous holes called pores Lack tissues that many other animals have Filter feeders Excretion and respiration are taken care of by

each individual cell Reproduce by budding (asexual) and can

regenerate lost parts Example

Porifera

Cnidaria 2 shapes:

cylindrical with tentacles on top (called polyp)

umbrella shaped structure with tentacles on bottom (called medusa)

Tentacles have stinging cells that can only be used once (food and protection)

No brain Examples:

Cnidaria

Platyheminthes

Have no true body cavity Nervous system with small brain Can reproduce asexually or sexually

(hermaphrodites) Absorb all materials through individual cells. Three classes:

Tubellaria (free living flatworms) Example:

Tremotoda (parasitic flukes) Cestoda (parasitic tapeworms)

Platyhelminthes

Nematoda

Round worms One way digestive system (mouth to anus) Separate sexes Small circular brain Examples:

Nematoda

Mollusca Soft, unsegmented body Body covered with thin layer called mantle which may

secrete a shell Three body parts:

Head Foot Viceral Hump (contains the internal organs)

Gas exchange through gills Classes

Gastropoda Pelycepoda (Bivalvia) Cephalopoda

Mollusca: Gastropoda

Mollusca: Pelycopoda

Mollusca: Cephalopoda

Annelida Segmented worms True body cavity Well developed digestive tract Hermaphorditic (sexually reproducing) Breath through moist skin Classes

Polychaeta – sand worm Oligochaeta – earthworm Hiridinea – leeches

Annelida: Polychaeta

Annelida: Oligochaeta

Annelida: Hiridinea

Arthropoda

Jointed appendages Exoskeleton usually made of chitin Well developed sense organs (compound eye

etc.) No blood vessels (blood circulated in

chambers called sinuses) Variety of respiratory organs (lungs, trachea,

gills)

Arthropoda: Crustacea

Arthropoda: Arachnida

Arthropoda: Chilopoda

Arthropoda: Diplopoda

Arthropoda: Insecta

Echinodermata

Most are sessile Most contain a hard calcium plate with bumps

and spines Simple nervous system with no brain Classes:

Crinoidea – feather stars Asteroidea – starfish Echinoidea – sand dollar, sea urchin

Echinodermata: Crinoidea

Echinodermata: Astroidea

Echinodermata: Echinoidea

Echinodermata: Holothuroidea

Chordata: Subphylum Vertabrata

Have a backbone Major classes:

Agnatha Chondrichthyes Osteichthyes Amphibia Reptilia Aves Mamalia

Agnatha Absence of jaws. Lack the paired fins (pelvic and pectoral). Skeleton made of cartilage. Round eel-like body with a flat caudal fin. Soft skin and no scales. They lack a swim bladder and gill covers. 7 gill slits on each side of the head. The lamprey are parasitic and the hagfish are scavengers. Ectothermic ( animals that cannot control their body

temperature). External fertilization. Oviparous ( egg laying) Marine and fresh water species are found. Gills used for respiration No external ears

Agnatha

Chondrichthyes Skeleton made of cartilage. Ventral mouth with several rows of

triangular teeth. No swim bladder. Ectothermic Internal fertilization. Marine organisms only. Gills used for respiration No external ears

Chondrichthyes

Osteichthyes Skeleton made of bone Swim bladder Ectothermic Various types of scales. Marine and fresh water species. Gills used for respiration External fertilization. No external ears

Osteichthyes

Amphibia Smooth moist skin. The toad is an exception with

rough dry skin. Ectotherms. During extreme environmental conditions

they either hibernate (winter) or estivate (summer). External fertilization (usually). Offspring develop

through a process called metamorphosis. Tadpoles (aquatic larvae) resemble fish.

Respire through poorly developed lungs and moist skin.

Digestive system is adapted to digest whole prey, swallowed by the organism.

Most amphibians contain three eye lids. Two are normal and one is transparent.

Amphibia

Reptilia Covered by a thick dry skin covered with

scales made of a protein called Keratin. Reproduction is sexual with internal

fertilization. Most lay eggs, while some snakes and

lizards give live birth. Respiration occurs through well

developed lungs. Ectotherms.

Reptilia

Aves Flight orientated Hollow bones Endotherms; their body temperature is

rather high, between 102-103 degrees F. No teeth and their beak is made of a light

protein keratin. Contain feathers, also made of keratin. Lay eggs with shells hardened with

calcium carbonate for added protection. External ears.

Aves

Mammalia Hair which is made of keratin. Endothermic. Mammary glands are used to produce milk to

nourish their young. An extended gestation period (uterine development)

is common in most placental mammals. Marsupials develop partially internally and partially

externally Monotremes lay eggs. Take care of young for extended periods after birth Teeth are imbedded in the jaw bone Well developed brain

Mammalia

Mammalia

Arthropoda88%

Mollusca5%

Chordata2%

Cnidaria1%

Platyhelminthes1%

Nematoda1%

Annelida1%

Porifera0%Echinodermata

1%

Other12%