Chapters 28-30: Diversity of Life

1. Taxonomic Classification

2. Viruses and Prokaryotes

3. Protists and Fungi

4. Plants

5. Animals

1. Taxonomic Classification

The Classification of OrganismsThere are ~1.5 million known species on

our planet.• total # or species on earth estimated to be

anywhere from 7 to 100 million

To study so many organisms and their evolutionary relationships requires:

• standard nomenclature• same name used worldwide for a given organism

• hierarchy, system of classification• allows organization by “relatedness”

By classifying organisms into groups(“taxa”), it help us to answer such questions as:•Is a snake more closely related to a worm or a lizard?•Is a mushroom more related to a plant or a mold?

All organisms are separated into 4 major groups (Kingdoms), which are further sub-divided into smaller and smaller groupings

The Taxonomic HierarchyEach level of the hierarchy is referred to as

a taxa:

Domain

Kingdom

PhylumClass

Order

Family

Genus

Species

Humans

eukarya

animal

chordates

mammals

primates

hominids

Homo

sapiensKing Philip Can Only Find Green Socks

Each organisms is named using both its genus and species.A species is defined as a group of organisms that interbreed with one another to produce fertile offspring.

beetle: Agra katewinsletaelichen: Caloplaca obamaeWasp: Polemistus chewbacca

Example: horse: Equus caballus donkey: Equus asinus

Same genus, different species. Their offspring, the mule, is sterile.

worm: Craniella abracadabra

The Major “Taxa”

The 3 Domains:

4 Kingdomsof Eukarya:

Bacteria Archaea Eukarya

Protists, Fungi, Plants & Animals

Bacteria:• “common” prokaryotes

Archaea (or archaebacteria):

• “unusual” prokaryotes or “extremophiles”• thrive in harsh environments (acid, high salt, boiling…)

Eukarya:• all organisms made of eukaryotic cells

Protists: single-celled eukaryotes

Fungi: multicellular; absorb food

Plants: multicellular; photosynthesize

Animals: multicellular; ingest food

2. Viruses and Prokaryotes

euk. cellbacteria viruses

Viruses are Small, Simple, Non-livingConsist of genetic material (DNA or RNA) inside a protein coat (may have a membrane envelope).

• no metabolic capabilities

• reproduce only within a host

• frequently “lyse” or kill host cell

Viruses come in Immense Variety

Differ in:

• size & shape

• genetic material

• mode of infection

• host specificity

• DNA, RNA, double or single strand

AIDS Virus Infection

The AIDS virus is a retrovirus:must convert RNA to DNA

Types of ProkaryotesProkaryotes = single-celled organisms

lacking nuclei and other organelles

Bacteria• live in every conceivable environment

• immense variety of metabolism, physiology

• play many essential biological roles• nitrogen fixation (all plants depend on it!)

• decomposition (essential for recycling of nutrients)

• digestion (gut flora in humans, cattle,…)

Archaea• thrive in very extreme environments

Prokaryotes come in 3 Basic Shapes

spherical(coccus)

rod-shaped (bacillus)

corkscrew-shaped(spirillum)

Extreme Habitats

3. Protists and Fungi

Types of ProtistsProtists = most single-celled eukaryotic

organisms

• some can form multicellular aggregates

• e.g., trypanosomes, plasmodium (causes malaria)

1) Protozoa (“first animals”)

• heterotrophs (ingest food)

• amoebae, paramecia, zooplankton, trypanosomes

• many are parasites

• 2 basic types of protist:

trypanosomes

zygote

sporozoite

gametocytes

Sexual phasein mosquito

femalegamete

malegamete

foodcanal

salivarygland

1. In the gut of a female Anopheles mosquito, gametes fuse, and the zygote undergoes many divisions to produce sporozoites, which migrate to her salivary gland.

2. When the mosquito bites a human, the sporozoites pass from the mosquito salivary glands into the bloodstream and then the liver of the host.

livercell

3. Asexual spores (merozoites) produced in liver cells enter the bloodstream and then the red blood cells. A sexual phase

in humans

5. Merozoites and toxins pour into the bloodstream when the red blood cells rupture, causing chills and fever.

4. When the red blood cells rupture, merozoites invade and reproduce asexually inside new red blood cells.

6. Some merozoites become gametocytes, which enter the blood- stream. If taken up by a mosquito, they become gametes.

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MALARIA

2) Algae (“photosynthetic protists”)

• phytoplankton

• “seaweeds”

(dinoflagellates,diatoms, volvox)

volvoxseaweed (kelp)

diatoms

The Fungi

Types of Fungiinclude:

• molds

• yeast

• mushrooms

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fertilization

zygospore

meiosisSexual

Asexual

sporangium

mycelium

+ strain

– strain

© Runk/Schoenberger/Grant Heilman Photography

Key Characteristics of FungiFungi digest organic material externally (they don’t ingest food like animals do):

• secrete digestive enzymes, absorb food

• some are detritus feeders (consume dead matter) some are parasites (prey on living)

• decomposition of dead organic matter is extremely important for ecosystems (recycles nutrients)

Fungal cells have cell walls (made of chitin)

Can reproduce sexually or asexually

4. Plants

What constitutes a Plant?

Major plant phyla, classes

Plants are multicellular, photosynthetic,and share characteristic modes of reproduction

The Bryophytes

Liverworts

Key features:

Mosses

• lack true leaves, roots, stems

• no internal vasculature

• rely mainly on diffusion

• limits their size

– Can live on bare rock, fences, cracks of sidewalks• Selective advantage to being small and simple

– Help convert rocks to soil

– Peat moss• Used as fuel

• Holds water

• Used in gardens to improve soil

Adaptations and Uses of Nonvascular Plants

The Tracheophytes

Tracheophytes are the vascular plants:

• contain vessels to transport material internally

There are 3 basic types of vascular plant:

• seedless vascular plants (e.g., ferns, horsetails)

• gymnosperms (all “cone-bearing” plants)

• angiosperms (all flowering plants)

Seedless Vascular PlantsHorsetails Ferns

• most primitive vascular plant

Seedless Vascular Plants

• Vascular tissue – Xylem conducts water and minerals– Phloem transports organic nutrients

• Have true roots, stems, and leaves• Seedless vascular plants produce windblown

spores (not seeds)

Seed PlantsGymnosperms and Angiosperms

– Most plentiful plants in the biosphere today

– Seeds contain a sporophyte embryo and

stored food within a protective coat

• Allows an embryo to survive during long

periods of dormancy

Gymnosperms

• conifers (pines, firs, etc…), cycads, gingko

• seeds produced in cones (not flowers)

All “cone-bearing” plants:

pine

cycad

gingko

juniper

Conifers– Pine, spruce, fir, cedar, hemlock, redwood,

and cypress– Adapted to cold, dry weather– Needlelike leaves conserve water with thick

cuticle and recessed stomata– Dominant sporophyte produces pollen cones

and seed cones– Wood is used in construction and for making

paper

AngiospermsAll flowering plants: • most dominant type of plant

*seeds are plant embryos + nutrients within a seed coat

• produce seeds* in flowers (via fertilization of gametes) • disperse seeds via fruits

Flower Diversity

Seed Plants• Life cycle

– Sexual reproduction in flowering plants is dependent on the flower

• Produces both pollen and seeds

– Pollination can be by wind or pollinator• Bees, wasps, flies, butterflies, moths, beetles, and even

bats• Many flowers are adapted to attract quite specific

pollinators

– Fruits• Final product of a flower• Aids in the dispersal of seeds

5. Animals

Invertebrates

Vertebrates

Characteristics of AnimalsAll members of the Animal Kingdom:

• consume food derived from other organisms

• feed by “ingesting” food• unlike fungi which “absorb” food externally

• consist of eukaryotic cells w/o cell walls

• are heterotrophs

• are multicellular

Most members of the Animal Kingdom:• have a symmetrical body plan

• radial or bilateral symmetry

• have distinct tissues, organs• reproduce sexually

Animal Diversity

Radial vs Bilateral SymmetryRadial Symmetry

• symmetrical halves “no matter how you slice it”

Bilateral Symmetry• only one plane of symmetry

bilateral symmetry

anterior

posterior

dorsal

ventral

Vertebrate vs InvertebrateVertebrate animals

• have a backbone or “vertebral” column

• less than 3% of known animal species

Invertebrate animals• NO backbone or “vertebral” column

• > 97% of known animal species

• any “non-vertebrate” animal

The vertebrate/invertebrate distinction is somewhat “old school”

They more or less constitute “sub-kingdoms”

Invertebrates

Major Invertebrate Phyla“Lower” Invertebrates

Porifera• all sponges

Cnidarians• anemones, coral, jellyfish

Platyhelminthes• all “flatworms”

Nematodes• all “roundworms”

“Higher” Invertebrates

Annelids• all “segmented worms”

Mollusks• snails, clams, squids

Arthropods• insects, spiders, crabs

Echinoderms• starfish, sea urchins

The Porifera (Sponges)

The simplest, most primitive animal phylum• lack distinct tissues or organs• some reproduce asexually (no union of sperm & egg)• don’t necessarily display bodily symmetry• are sessile (i.e., fixed in placed, “non-motile”)

Simple Sponge AnatomyFilter feeder

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b. Sponge organization

c.

d.

sponge wall

pore

spicule

amoebocyte

collar cell (choanocyte)

nucleuscollar

flagellum

amoebocyte

osculum

H2O inthroughpores

H2O out

centralcavity

epidermalcell

a. Yellow tube spoge,Aplysina fistularis

a: © Andrew J. Martinez/Photo Researchers, Inc

The CnidariansAnemones, jellyfish,corals…• have radial symmetry

• are sessile, or free- floatingAll aquatic• only 2 embryonic germ layers

• endoderm (inner layer)

• ectoderm (outer layer)

Mouth and

anus

Cnidarian DiversityCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

b. Sea anemone, Corynactis c. Cup coral, Tubastrea

e. Jellyfish, Aureliad. Portuguese man-of-war, Physalia

b: © Azure Computer & Photo Services/Animals Animals; c: © Ron & Valerie Taylor/Bruce Coleman, Inc.; d: © Runk/Schoenberger/Grant Heilman Photography; e: © © Amos Nachoum/Corbis

The Platyhelminthes (Flatworms)

• bilateral symmetry

• have internal organs

• lack respiratory, circulatory systems

• many are parasites

“Planaria”“Tapeworms”

The Nematodes (Roundworms)• estimated 500,000 different species

• small in size, frequently parasitic

• important decomposers

fresh water nematode

Trichinella

“heartworms”

What some roundworms can do to you– Trichinosis

• Caused by Trichinella spiralis• Humans contract the worm by eating undercooked

pork• Larvae migrate out of intestines and form painful

cysts in the muscles

– Elephantiasis• Caused by a filarial worm • Migrates into lymphatic vessels and prevents

lymph drainage• Swelling of limbs occurs

– Pinworms and hookworms• Roundworm parasites which cause problems in

children

Annelids (Segmented Worms)Earthworms, leeches, sandworms…

• repetitive body segments

• closed circula- tory system*

• digestive tract with 2 openings (mouth, anus)*

• Gas exchange is across the body wall

The MollusksGrouped into 3 main classes:

GASTROPODS (snails & slugs)

BIVALVES (clams, scallops, oysters)

CEPHALOPODS (squid, octopus, cuttlefish)

snail scallop

octopus squid

nautilus

Cephalopods:• most advanced mollusks

• unusually high intelligence

http://www.youtube.com/watch?v=jN99Kx_ghC8http://www.youtube.com/watch?v=p9A-oxUMAy8

The Arthropods3 main classes of Arthropod: INSECTS

• estimated 9 million species!

ARACHNIDS• spiders, ticks scorpions, mites

CRUSTACEANS• crabs, shrimp lobsters, barnacles

Characteristic Arthropod FeaturesHave an exoskeleton (external skeleton)

• must “molt” for growth to occur

Segmented bodies

Open circula- tory systems

• e.g., moths, butterfliesMany undergo metamorphosis

The Echinoderms

Starfish, sea urchins,sea cucumbers…• calcium carbonate endoskeleton

• radial symmetry (adult)• larvae are bilateral

Vertebrates

The Phylum Chordata

Main characteristics of the Chordates:• have a notochord

• usu. gives rise to the backbone during development

• have a hollow nerve cord• becomes brain & spinal cord during development

• pharyngeal “gill slits”• may disappear during development

• have a tail• may disappear during development

***All vertebrates are chordates but not all chordates are vertebrates***

Major Chordate Classes

Agnatha• “jawless” fishes

Chondrichthyes• cartilagenous fishes

Osteoichthyes• bony fishes

Amphibians• frogs, salamanders…

Reptiles• lizards, snakes, turtles…

Birds (Aves)• chickens, eagles…

Mammals• humans, cats, dogs…

Agnatha

Jawless fishes:

• hagfish

• lamprey

Chondrichthyes

Sharks, rays and skates• skeleton made of cartilage* (no bone)• have jaws*

Osteoichthyes

All bony fishes (have true bone*)• most diverse class of vertebrates

• have scales* • air bladder* (precursor to lungs?)

Amphibians

• need water to reproduce

• breathe through skin &lungs*

• 1st vertebrates to leavethe water

Reptiles

• water-proof skin*

• first organisms to develop in an amniotic egg*• can develop away from water

• first true “land” vertebrates

• A water-impermeable structure which contain a fluid and so the embryo to develop on land without danger of desiccation.

• It also contain a yolk to nourish the developing organism.

• Amniotic eggs protect the developing organism, as well as aid in gas and energy exchange.

What is an amniotic egg?

YOLK: sacs that contains the nutrients

CHORION: encloses all the other sacs

ALLANTOIS: sac that stores the metabolic wastes

AMNION: A fluid-filled sac that provides an aquatic environment to the developing embryo/

Amniotic egg structure

Birds (Aves)

• thought to have evolved from reptiles

• wings & feathers*

• first homeothermic organisms*• maintain constant body temperature (warm-blooded)

• amniotic egg

Mammals

• most have placenta*• young develop internally

• mammary glands*

• homeothermic

• hair*

• nourish young with milk