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Classification of Living Things
Tools Used to Classify Organisms
1. Comparative Morphology
Compares Physical Structures, Traits
2. Evolutionary Relationships
Related Organisms with common
ancestors, Derived Characters
3. DNA/RNA comparison
Timeline of Classification
1. 384 – 322 B.C. Aristotle
– 2 Kingdom Broad Classification
2. 1735 - Carl Linnaeus
– 2 Kingdom Multi-divisional Classification
– Kingdom, Phylum, Class, Order, Family
Genus, Species
3. Evolutionary Classification – (After Darwin)
– Group By lines of Evolutionary Descent
4. 5 Kingdom System – 1950s
5. 6 Kingdom System – 1990s
6. 3 Domain System – 1990s
Linnaeus Divisions Still Used in Modern
Classification
1. Kingdom – largest group
2. Phylum
3. Class
4. Order
5. Family
6. Genus
7. Species
(Most Closely Related)
Mnemonic Device – To help remember
categories and order
Kingdom Phylum Class –
Order –
Family Genus Species -
King
Phillip
Came
Over
For
Ginger
Snaps
Taxons
Within each category, a particular group is
called a Taxon
Many Taxons for each category
Ex: Mammalia is the Taxon for the Class
category in Humans
Ex: Homo is the Taxon for the Genus
category in Humans
Carnivora is the Taxon for the Order
category in Lions
Linnaeus Introduced Scientific Naming
• Binomial Nomenclature is the 2 word scientific
name of an organism
– Uses Genus and Species
• Genus is capitalized, not species, all italicized
• In writing the name, can’t italicize, so underline
– Homo sapien (Genus and species of Human)
– Panthera leo (Genus and species of Lion)
Example Classification
• Lion
• 1. Kingdom – Animalia (all Animals)
2. Phylum – Chordata (All vertebrate animals)
• 3. Class – Mammalia (All Mammals –
mammary glands)
4. Order – Carnivora (Meat eaters)
5. Family – Felidae (includes all Cats)
6. Genus – Panthera (Includes all
roaring Cats)
7. Species – leo (Lions)
From Kingdom to Species
6 Kingdom System
Animalia
Plantae
Fungi
Protista
Eubacteria
Archaeabacteria
Now, using the sheet like the chart below,
fill in the pertinent data—as described in
the title—GET FROM ME!
3 Domains – write this in the domain
name box.
• Eubacteria – Common Bacteria
• Archea Bacteria – ancient Bacteria
• Eukarya – Includes everything else,
Protist, Fungi, Plants, and Animals
4. Three Domain System
1. Domain Bacteria
– Corresponds to Eubacteria Kingdom
(Characteristics)
– Unicellular Prokaryotic Organisms
• No Nucleus
• Ecologically Diverse – live everywhere!
• Metabolically Diverse
– Cell Walls contain substance called Peptidoglycan
– special protein and sugar
• Target of many Antibiotics
Three Domain System
• 2. Domain Archaea – “Ancient Bacteria”
– Corresponds to Kingdom
Archaeabacteria
– Unicellular, Prokaryotes
• Metabolically Diverse
• No nucleus
• Live in Extreme environments like
those of early Earth
• Cell walls without Peptidoglycan
– A trait used to distinguish between
Archaea and Bacteria Domains
Three Domain System
3. Eukarya
Contains Kingdoms:
Protista, Fungi, Plantae, Animalia
Eukaryotic, single or multi-cellular
Organisms
Nucleus
Most visible life
Humans are in Domain Eukarya
BEFORE BEGINNING THIS SECTION,
YOU’LL NEED ANOTHER SHEET FROM
ME!
Invertebrate Overview:
Kingdom Animalia
Phylum Porifera
-sponges
Phylum Cnidaria
-jellyfish, sea anemones
Phylum Platyhelminthes -tapeworms, flukes
Phylum Nematoda
-pinworms, Ascaris
Phylum Mollusca
-clams, squid, octopi
Phylum Annelida
-earthworms, leeches
Phylum Arthropoda
-insects, crayfish
Phylum Echinodermata -starfish, sand dollars
Phylum Porifera
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•
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•
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•
•
Ex. Sponges
Multicellular WITHOUT TISSUES
Heterotrophic filter feeders
Asymmetrical
No cephalization present
No coelom
Basic body parts: ostia, spongocoel, osculum,
choanocytes with flagella
Figure 33.2 Sponges
Figure 33.3 Anatomy of a sponge
Porifera
Sponges are aquatic animals that represent a
transition from unicellular to multicellular life. Of
the 10,000 species of sponges, only about 150
species live in fresh water. Adult sponges are
sessile, meaning that they attach themselves
to a surface and do not move. Because they
are sessile, sponges are filter feeders,
screening food out of the water that flows
through their body.
Porifera / Sponges
Phylum Cnidaria
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•
•
•
•
Ex. Jellyfish
Two germ layers: ectoderm and endoderm
No cephalization
No coelom
Soft, sac-like body plan, two way digestion (with one
opening – mouth)
• Two body forms: sessile polyp and free-swimming
medusa
• Basic body parts: bell, cnidocytes with nematocysts,
tentacles, gastrovascular cavity, gonads
Figure 33.4bx Jelly medusa
Table 33.1 Classes of Phylum Cnidaria
Figure 33.4 Polyp and medusa forms of cnidarians
Figure 33.5 A cnidocyte of a hydra
Cnidaria
Freshwater hydra, jellyfish, and corals go through a
transition in body forms. The medusa stage (bellshaped) is specialized for swimming and the polyp
stage (vase-shaped) is specialized for a sessile life.
All members of the phylum have these two stages at
one time in their life, even though the medusa stage
may be found only as an embryo. All cnidarians have
tentacles containing cnidocysts and nematocysts,
specialized stinging cells for defense and capturing
food.
Cnidaria / Hydra
Cnidaria / Coral
Cnidaria / Jellyfish
Phylum Platyhelminthes
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•
•
•
•
•
•
•
Ex: tapeworms
Three germ layers: ectoderm, mesoderm, endoderm
Bilateral symmetry
Cephalization is present
No coelom – acoelomates!!!!
Use diffusion to transport materials through body
Mouth forms first – protostomes
Basic body parts: mouth, pharynx, intestine,
ganglia, flame cells
Figure 33.9x A flatworm
Figure 33.10 Anatomy of a planarian
Figure 33.12 Anatomy of a tapeworm
Phylum Nematoda
• Ex. Pinworms
• Three germ layers present – ectoderm, mesoderm,
endoderm
• unsegmented
• Bilateral symmetry
• Cephalization present
• Pseudocoelom present
• Mouth forms first – protostome
• Basic body parts: mouth, anus, intestines
Figure 33.25a Free-living nematode
Figure 33.25ax Nematode, C. elegans
Nematoda
Roundworms have a long, slender body
that tapers at both ends. They range in
length from 1 millimeter to 4 feet in length.
This phylum is the first to have a digestive
tract with two openings, which is a major
advancement over the phyla up to this
point. The vast majority of these animals
are free-living, but there are about 150
species that are plant and animal parasites.
Nematoda
Nematoda / Roundworms
Phylum Mollusca
• Ex. Clam, squid
• Three germ layers present: ectoderm, mesoderm,
endoderm
• Have an external or internal shell for support
• Bilateral symmetry
• Cephalization present
• Has a TRUE COELOM
• Mouth develops first – protostome
• Basic body parts: gills, specialized “foot”
Table 33.3 Major Classes of Phylum Mollusca
Figure 33.18x Garden snail
Figure 33.20 A bivalve: Scallop
Figure 33.22 Cephalopods: Squid (top left and bottom left), nautilus (top right), octopus (bottom right)
Mollusca
Mollusca - Snails, Clams, Squid and Octopus are the
first animals with a true coelom, a hollow, fluid-filled
cavity completely surrounded by the mesoderm. The
phylum is divided into three classes.
Gastropoda: most members of this class have a one-piece,
external shell. Gastropods include snails and slugs.

Bivalvia: members have an external shell divided into two
halves that are connected by a hinge. Bivalves include clams,
oysters, and scallops.
Cephalopoda:these marine mollusks are the most advanced
group in the phylum. Their nervous and circulatory systems are
highly advanced and they have an internal shell supporting the
body. Octopus and squids are cephalopods, including the
giant squid - the world's largest known invertebrate.

Mollusca / Octopus
Mollusca / Squid
Mollusca / Clams
Mollusca / Snails
Phylum Mollusca
Body Plan
• Different shapes of Mollusks (clam, octopi)
are evolution of Basic Body Plan
• Basic Plan: 4 Specific Mollusk Parts
– Foot – many shapes, parts; movement
– Mantle – tissue that covers body
– Shell – made by glands in mantle, covers body
– Visceral Mass – contains internal organs
Figure 27–21 The
Mollusk Body Plan
Snail
Squid
Early
mollusk
Shell
Mantle cavity
Foot
Clam
Gills
Digestive tract
VISCERAL MASS
SHELL
MANTLE
FOOT
Feeding
• All types of diets
• Radula: Flexible, tongue like part with
hundreds of teeth attached
– Scrape algae, soft tissues of plants or drill through
shells, tear soft tissue
• Sharp Jaws used by Octopi,Sea,Slugs
– Can also contain poison
• Clams, Oysters, Scallops filter feed through
Siphon
– Food trapped on sticky Gills
Respiration and Circulation
• Aquatic: Gills inside Mantle Cavity O2  Blood
Vessels
• Land: Mantle Cavity O2  Blood Vessels
– Require moist lining
• Open Circulatory System – carries O2, nutrients
– Heart pumps Blood to vessels
– Vessels to Sinuses
– Sinuses to Gills  O2 picked up, CO2 released
– Blood Back to Heart
Excretion
• Cells Release Nitrogen Waste  Blood
• Nephridia Remove Nitrogen Waste  Out of Body
Nephridium
Response
• Complexity of Nervous System Varies
• 2 Shelled Mollusks – Ganglia, Nerve Cords,
Simple Sense Organs
– Clams
• Octopi – Brains; Memory!
• Chromatophores – Skin Cell ability to change
skin color and texture to match surroundings
– Most Intelligent Invert Animal
– Can be trained to perform tasks
Movement
• Many Different Ways
• Snails – S L O W….
– Secrete Mucus on Foot; Ripple Foot
• Octopi – FAST
– Draws Water into Mantle, Forces out
through Siphon
Reproduction
• Snails and 2 Shelled – Sexually, External
– Release high # of Eggs and Sperm in water
– Develop into free swimming larvae
– Larvae called Trochophore
• Some Hermaphroditic
• Tentacled Mollusks – Internal Fertilization
Class Gastropoda
“Stomach Footed”
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•
•
•
•
Nudibranchs, Slugs, Snails
Ventral Muscular Foot to Move
1 or no Shell
Can secrete toxins, ink
Ex: Nudibranchs can eat Cnidarians; Hijack
Nematocysts for Protection
Snail External Anatomy
Nudibranch with spiny tentacles
Class Bivalvia
2 Shelled Mollusks
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•
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•
Oysters, Clams, Mussels, Scallops
2 Shells Held By 1 or 2 Muscles
Flap Shells, Burrow to Move
Filter Feed – Cilia on Gills  Current
Can use Muscles near Mouth to get Food
Anatomy
of a Clam
Section 27-4
Stomach
Coelom
Shell
Heart
Nephridium
Adductor muscle
Mouth
Anus
Excurrent
siphon
Adductor
muscle
Incurrent
siphon
Gills
Mantle cavity
Intestine
Mantle cavity
Foot
Class Cephalopoda
“Intelligent” Mollusks
•Octopi, Squid, Cuttlefish, Nautiluses
•Head attached to Foot
•Complex Eyes
•Foot -- Divided into Tentacles
•8+ with Suckers
•Small Internal Shell – adapted or lost
•Only Nautiluses have External Shell
Cephalopod Examples
Phylum Annelida
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Ex: earthworm
Three germ layers present
Bilateral symmetry present
Cephalization present
True coelom present
Mouth develops first – protostome
Basic body parts: mouth, anus, specialized
intestine, segments
Figure 33.23x External anatomy of an earthworm
Anneilda
Segmented worms are more advanced than
roundworms and have several visible
characteristics that distinguish them. They are
named for the many body segments that make an
annelid look like it is composed of a series of
"rings". Unlike roundworms, the segmented
worms have an obvious head and tail. All
segmented worms have one of two types of
structures extending from their bodies that are
used for locomotion. Most annelids have hair-like
bristles known as setae
Segmented Worms
Figure 33.23 Anatomy of an earthworm
Phylum Arthropoda
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Ex. Insects, spiders, crayfish, millipedes, centipedes
Three germ layers present
Exoskeleton present that requires molting (shedding)
Jointed appendages
Bilateral symmetry
Cephalization present
True coelom present
Mouth forms first
Basic body parts: head, thorax, abdomen, (or cephalothorax
and abdomen), spiracles and tracheae, open circulatory
system
Table 33.5 Some Major Arthropod Classes
Figure 33.26 External anatomy of an arthropod
Figure 33.30b Spider anatomy
Figure 33.33 Anatomy of a grasshopper, an insect
Phylum Arthropoda
“Jointed Foot”
Largest Animal Phylum
Section 28-1
Concept Map
Anthropods
feed
on
respire
using
All types
of foods
Tracheal
tubes
reproduce
using
Internal
fertilization
Book lungs
have
well-developed
External
fertilization
Book gills
Heart
Brain
Muscles
Phylum Overview
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•
•
•
Most ‘successful’ Phylum of All Time
750,000 species identified
Ex: Shrimp, Butterflies, Crabs, Spiders
Covered in hard Exoskeleton made of Chitin
– Gives Support
– Adapted to environment – water
loss/protect
• Jointed Appendages
– Legs, Antennae
– Increased Muscle Need for Joint Movement
Evolution of Arthropods
• 600 MYA – Appeared in Sea
• Moved into all Environments
– Air, Water, Land
• Body plan modified from many segment
origin
• Trilobite Fossil 500MYA
• Modern Arthropods – fewer segments,
more specialized appendages
– Cephalothorax, Thorax, Abdomen, Head
The Exoskeleton
• Provides Protection, Support
• Adapted to Environment, Lifestyle
– Fruit flies versus Lobsters
• Exoskeleton – environment specific
– Specific to Oxygen requirements
– O2 level has changed, insect size has changed
– Molting – shedding of exoskeleton to
accommodate for growth
Figure 33.27 A trilobite fossil
Appendages
• Jointed and attached to body segments
• Evolved over time
– Wings, Legs, Antennae, Claws, Mouthparts,
Tails, Flippers
• Adaptive Radiation – new characteristics can
introduce arthropods to new habitats
– Ex: Wing Evolution  New Habitat (Sky)
Feeding
• All Types of Diet
• Evolution – Mouthpart Adaptation and
Diversity
–Extreme range of mouthparts –
biting, sucking, piercing, etc
–Mandible – chewing jaw ‘joint’
Excretion
• Malpighian Tubules – Sac like organs
– Extract wastes from Blood, add to feces
• Aquatic – Tubules excrete directly into
water
• Compromise between exoskeleton
protection with exchange of materials
and gases
Respiration and Circulation
• 1. Terrestrial Insects Breath through
Tracheal Tubes
• 2. Spiders – “Book Lungs”
–Stacked Layers of Respiratory Tissue
• 3. Aquatic Arthropods – Feather-like
Gills
• Open Circulatory System
Class Insecta
• 3 Body Segments: Head, Thorax,
Abdomen
• One/Two Pairs of Wings attached to
Thorax
• 3 Pairs of Legs
• Antennae Present
• Metamorphosis – 2 Types
Figure 33.33 Anatomy of a grasshopper, an insect
Metamorphosis – Development Stages
• Incomplete – Immature Stage looks like
smaller Adult Stage
– Nymph  Adult - Grasshopper
• Complete – Larval Stage specialized for
growing
– Look Different – Caterpillar/Butterfly
Section 28-3
Metamorphosis
Adult
Eggs
Adult
Eggs
Complete
Metamorphosis
Incomplete
Metamorphosis
Nymph
Adult
Larva
Nymph
Pupa
Immature
Nymph
Adult
Larva
Figure 33.34 Metamorphosis of a butterfly
Class Crustacea
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Lobsters, Shrimp, Crabs
2 Body Segments – Abdomen Cephalothorax
Swimmerets –for swimming
4 pairs of Walking Legs
Chelipeds - Pinchers
Gills
Mandible
Antennae
Figure 33.26 External anatomy of an arthropod
Class Arachnida
• One/Two Main Body Parts – Cephalothorax,
Abdomen
• 6 Pairs of Appendages – 2 Feeding, 4 walking
• Fangs
– Secrete digestive juices and poisons
• Book Lungs
• No Antennae
• Web-making –predation and mating behaviors
Figure 33.30b Spider anatomy
Figure 33.30x Lycosid spider: female with offspring
Ecology of Arthropods
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Compete with Humans for food
Pollinators
Provide food for Humans, food chain
Pesticide Pollution to Combat
Arthropods
• Carry Disease
–Malaria
Arthropoda
Three-fourths of all animal species, including spiders,
crayfish, and insects, are arthropods. This phylum is
composed of a very diverse group of animals that are
bilaterally symmetrical. The following characteristics have
allowed arthropods to adapt to almost every environment on
Earth:
•Jointed appendages: the phylum name means
"jointed foot". All the appendages (body extensions)
of arthropods are jointed, giving them a wide range
of controlled motions.
•Exoskeleton: the exoskeleton provides support
and protection. It is composed of three layers that
are secreted by the epidermis.
Segmented body: the segments in the arthropod body make
movement possible, even with the hard exoskeleton.
Arthropod / Spiders
Arthropod / Crayfish
Phylum Echinodermata
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Ex: starfish
3 germ layers present
Biradial symmetry in adults
No cephalization in adults
True coelom present
Anus forms first – deuterostome!!!
• Basic body parts: spiny skin, endoskeleton, water
vascular system, tube feet
Figure 33.37 Echinoderms: Sea star (top left), brittle star (top right), sea urchin (bottom left), sea lily
(bottom right),
Figure 33.38 Anatomy of a sea star
Echinodermata
Starfish, sand dollars, and sea urchins are found in
marine environments ranging in depth from shallow
tide pools to 10,000 meters. Most of the 7,000
species of echinoderms have a type of radial
symmetry called pentaradial symmerty, in which
the body parts extend from the center along five
spokes.
•They have a water-vascular system - a
network of water-filled canals inside their
body.
They have many small, movable extensions of the
water-vascular system called tube feet, which aid in
movement, feeding, respiration, and excretion
Echinodermata / Starfish
Echinoderms / Sand dollars and Sea
Urchins
Phylum Echinodermata
Spiny Skin
Starfish, Sea Cucumbers, Sea Urchins,
Sand Dollars
Figure 33.37 Echinoderms: Sea star (top left), brittle star (top right), sea urchin (bottom left), sea lily
(bottom right),
Phylum Overview
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Sessile/Slow Moving Animals
5 Spines typical
Radial Symmetry
Thin ENDOSKELETON
Water Vascular System
Tube Feet
External Sexual Reproduction
Closest Relation to Chordates
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•
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Develop from Bilateral Larvae
Deuterostomes – Developmental Pattern
Radial Cleavage
Mouth End Forms opposite of Anus End
Functions
• Water Vascular System -- Network of Hydraulic
Canals
– Radiate from center  Tube Feet
– Tube Feet – locomotion
– Gas Exchange - Gills
• Feeding – Mouth on Bottom  Short
Digestive Tract  Anus on Dorsal Side
Figure 33.38 Anatomy of a sea star