Lesson Plan: How we classify
Living Things
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Introduction
An
introduction to taxonomy in general and taxonomy of animals in
particular.
Unit
Outline
*Objectives
*Building
Background
*Presentation
Material
*Student
Activity
*Enrichment
Activities
*Unit
Wrap-Up
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Objectives
As a
result of completing this unit, students should be able to:
* name and describe the 5 Kingdoms of living
things: Animalia, Plantae,
Fungi, Protista,
and Monera;
* name and describe these 7 Phyla of
animals: Annelida, Arthropoda,
Chordata, Cnidaria, Echinodermata,
Mollusca, and Porifera; and
* take the quiz and score well.
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Building Background
There are
many systems for classifying living things. The first system was
devised
by Carolus Linnaeus in the mid-1700s. He introduced
the 7 basic
levels of
classification: Kingdom, Phylum (plural Phyla), Class, Order,
Family, Genus, and Species. The recent discovery of organisms living in
extreme
environments and recent developments in genetic analysis have
resulted
in rethinking the way living things are related and, therefore,
classified.
This lesson will introduce the students to the classical
Linnaean
system of classification and focuses on the animal kingdom,
especially
ocean-dwelling organisms.
One
system of classification currently in wide usage divides the world of
living
things into 5 Kingdoms:
* Monera:
Single-celled organism lacking a nucleus containing genetic
material. Includes bacteria.
* Protista: Mostly
single-celled organism with a nucleus containing
genetic material.
Includes some algae, amoebas, and slime molds.
* Fungi: Multi-cellular organism which
absorb food directly from their
environment.
* Plantae:
Multi-cellular organism which manufactures food using energy
from sunlight.
* Animalia:
Multi-cellular organism which injests food.
This
chart (borrowed from David P. Chynoweth) shows the relations among
these 5
kingdoms.
A Table
of Animal Phyla, also borrowed from David P. Chynoweth, is
available
which lists the major animal phyla, but for the purposes of this
lesson,
only the following phyla and classes are considered:
* Porifera
(sponges): tubular, cuplike, vaselike, sprawling;
circulate
water through
numerous pores on its body to collect food.
* Cnidaria
(cnidarians - the "c" is silent and the "i"
is long): hydra,
jellyfishes, corals, sea anemones; bodies have stinging
cells.
* Mollusca
(mollusks): snails, slugs, clams, squids, octopuses;
soft-bodied with
external or internal shell(s).
o Bivalvia: clams and mussels; "2-shelled"; have a
pair of external
shells
protecting the soft body.
o Gastropoda: snails and slugs; "stomach-foot";
either a single
external
shell or no shell.
o Cephalopoda: squid, octopus, nautilus;
"head-foot"; either a
single external
or internal shell, or no shell.
* Annelida
(annelids): earthworms, leeches, polychaetes;
segmented
worms.
* Arthropoda
(arthropods): crabs, lobsters, spiders, insects; external
skeleton and
jointed appendages (limbs).
o Arachnida: spiders, ticks, scorpions; 8-legged.
o Insecta: ants, bees, butterflies, etc.; 6-legged.
o Crustacea: crabs and lobsters; 5 pairs of appendages.
* Echinodermata
(echinoderms): sea stars, sea urchins, sea cucumbers;
spiny-skinned
marine organisms.
* Chordata
(chordates): invertebrates (tunicates, lancelets) and
vertebrates
(fishes, amphibians, reptiles, birds, and mammals); have
(at some stage of
development) a notochord which, in most classes,
gives rise to the
spine, and pharyngeal slits (gill-like openings).
o Chondrichthyes: sharks and rays; jawed fishes with skeleton
made
of
cartilage.
o Osteichthyes: other jawed fishes; jawed fishes with
skeleton made
of bone.
o Amphibia: frogs, salamanders; legged animals which spend
part of
their life
as water-breathers.
o Reptilia: snakes, lizards, alligators, turtles;
cold-blooded
animals with
scaly skin.
o Aves: birds;
warm-blooded animals with feathers.
o Mammalia: mammals; warm-blooded animals with hair.
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Presentation
Material
* Explain that living things are classified
not only by their physical
appearance, but
also by evolutionary relationships and genetic
analysis.
* Carolus Linnaeus
developed the first system of classification which is
still in use
today. Every organism is assigned a unique Genus and
Species, usually using Latin terms, to
name it. For the human being
the genus and
species are Homo sapiens.
* Define the 5 Kingdoms and their general
characteristics.
* Define the 7 Phyla and their general characteristics.
* For the molluscs,
the arthropods, and the chordates, define the
respective
Classes and their general characteristics.
* Show pictures of specimens and challenge
the students to identify the
Phylum and, in some
cases, the Class. The quiz at
http://www.best.com/~aha/taxonomy/quiz.html contains images of quite a
few animal
specimens. A list of the specimens in the quiz is
available.
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Student Activity
Each
student could be given access to the World Wide Web either
independently or in small groups to take the quiz.
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Enrichment Activities
Students
might be asked to keep a journal of every animal they can see over
a weekend
and report to the class. Another interesting project might be to
visit the
library to learn about extinct animals such as dinosaurs,
trilobites,
bryozoans (some species are still living today), and so forth.
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Unit Wrap-Up
Review
the 5 Kingdoms of living things and their general characteristics.
Review
the Phyla and Classes of animals and their general characteristics.
Remind
the students that there are many more Phyla and Classes than
discussed.
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