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					                         BIO101 LABORATORY 11

         ANIMAL BODY PLANS AND EVOLTIONARY DIVERSITY



Phylogenetic Tree of the Animal Kingdom
Definitions of Major Divisions

   (A) Formation of Coelom - Protostomes vs Deuterostomes

   In echinoderms and chordates, for example, the anus forms first, and then the
   mouth. In animals belonging to several other important phyla, on the other
   hand, such as arthropods, annelids and mollusks, the mouth forms first,
   followed by the anus. For this reason arthropods, annelids and mollusks are
   sometimes called protostomes (Greek: proto = the first; stoma = mouth) and
   echinoderms and chordates are called deuterostomes (Greek: deutero = the
   second). It is also possible to take an echinoderm or chordate embryo at the 2-
   cell or 4-cell stage of development, separate the cells, and still have each cell
   continue on to develop into a complete, viable organism. This is not possible
   with protostome embryos. If they are separated at this stage, the cells will not
   develop into complete, viable organisms. For this reason, protostomes are said
   to display determinate cleavage, and deuterostomes are said to have
   indeterminate cleavage. You will be introduced in lecture and in subsequent
   laboratory exercises to other important developmental characteristics that
   distinguish protostomes from deuterostomes.




                 Asymmetry                Radial                   Bilateral
                                         Symmetry                 Symmetry
   (B) Symmetry

   Animals can be grouped according to the type of symmetry they show. Some
   groups, such as the phylum Porifera, show no particular pattern of symmetry
   (asymmetry). That is, no line of bisection exists that could divide the organism
   into two halves. Other groups, including the Cnidaria and Echinodermata
   show radial symmetry, where more than one hypothetical bisection can be
   visualized (lines A, B, and C can each bisect the organism). A third pattern,
   seen in most phyla of animals, is bilateral symmetry, where only one
   hypothetical bisection can be visualized (only line A can bisect the organism
   into two halves). While these patterns can be seen readily, the implications
   and constraints of each is what is of greatest importance to our study of animal
   body plans. Make a list of advantages as well as constraints of each of these
   three patterns of symmetry. In later labs where you are examining different
   animals, test your ideas in your list to see if you were on the right track.



                                           2
(C) Body Cavities

One of the primary ways zoologists group animals has to do with the presence
or absence of a coelom, and how the coelom is formed. The three basic
patterns are pictured in the figure below. You should know which type of
coelom is found in each of the major animal phyla.


    Tissue                                                      Body Plan
    Layers                                                        Type
     and
    Cavities
        Endoderm                                        Acoelomate

         Mesoderm

            Ectoderm
                                                         Pseudocoelomate
                  Gut

       Pseudocoel

               Coelom                                      Coelomate




(D) Segmentation, Cephalization, and Tagmosis

Segmentation, also known as metamerization, is the structural grouping of
parts of an animal body into discrete segments. Cephalization means that
there is a head, and therefore a head- vs a tail-end to the animal. While at first
seeming a bit simplistic, cephalization has tremendous implications for
animals.

   •   Can you think of any advantages of cephalization?
   •   Is cephalization dependent on any particular type of symmetry?
   •   Can cephalization occur in protostomes as well as deuterostomes?

Tagmosis occurs in segmented animals where groups of segments are
organized into functional units. A good example is in arthropods, where
segments are grouped into a head, a thorax, and an abdomen, each having its
own suite of functions.


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1. Descriptions

You will be introduced to the proper use of a compound microscope and have an
opportunity to learn the techniques of drawing biological specimens.

Kingdon Protista (Single-celled Eukaryotes)

In this session you will learn how to prepare a wet mount slide for microscopic
examination. You will also examine unicellular eukaryotes in this laboratory session.
You will see examples of Protists.

Kingdom Animalia (Heterotrophic Multicellular Eukaryotes, except Fungi)

Phylum Porifera (Sponges)

Poriferans are composed of colonies of cells that interact together, but do not have a
tissue-level of cellular organization. They commonly exhibit an asymmetrical “body”
plan. This group represents an intermediate stage between an ancestral state of
organization (a colony of independent cells), and that of derived animals that are
composed of tissues and organ systems.

Phylum Coelenterata (Cnidaria)

The coelenterata (cnidarians) are multicellular, radially symmetrical, aquatic animals that
have sac-like bodies composed of two distinct tissue layers, the outer ectoderm and inner
endoderm. These layers are separated by an acellular jelly-like layer called the mesoglea.
They have distinctive stinging cells called Nematocysts. You will examine 3 classes:
Hydrozoa, Scyphozoa, and Anthozoa.

Phylum Platyhelminthes (Flatworms)

Flatworms are the most structurally simple of all the worms. These animals have a third
tissue layer, the cellular mesoderm, which lies between the ectoderm and endoderm.
They are Aceolomates because the gut lies in direct contact with the endoderm and thus
there is no coelomic cavity present. You will examine two classes of platyhelminthes
including the non-parasitic Turbellaria and the parasitic Cestoda.

Phylum Nematoda (Roundworms)

Nematodes are pseudocoelomates which means that the coelom exhibited in this animal
is composed of a gap between mesoderm and endoderm tissue layers. Many of the
species in this phylum are parasitic, such as the roundworm Ascaris.




                                             4
Phylum Annelida (Earthworm)

The members of the Phylum Annelida are divided into three classes. Class Polychaeta
includes all bristle worms; Class Hirudinea encompasses all the leeches; and Class
Oligochaeta includes earthworms. This is the most ancestral phylum to have a coelomate
body plan, where mesoderm splits to form the coelomic cavity. The unique feature which
typifies all annelids is that they have elongated segmented bodies where the segments
involve not only the external structures but also almost all of the internal structures. You
will be able to study these features on the earthworm.

Phylum Arthropoda: Phylum Arthropoda contains more species of animals than all
other phyla combined and is represented by both aquatic and terrestrial forms. One of the
primary characteristic of this phylum is segmented appendages.

Class Arachnida: Spiders, mites, horseshoe crabs, scorpions, daddy longlegs, and ticks.

Class Chilipoda: Centipedes; Class Diplopoda: Millipedes

Class Hexapoda: flies, crickets, grasshoppers, butterflies, bees, fleas, cockroaches, and
beetles.

Class Malacostraca: Lobsters, shrimps, crabs, crayfish

The class Hexapoda contains more species than all other groups of animals combined.
Insects are primarily terrestrial and their success on land is largely due to a combination
of anatomical features such as a light, chitinous, waterproof exoskeleton, internal
respiratory surfaces, internal fertilization, and wings.

Phylum Mollusca (Clams, Octopus, Snails)

All members of the phylum Mollusca have bodies which are variations on the same basic
plan consisting of a head, foot, and visceral mass. Most have their soft bodies supported
by a calcareous shell which may be conical (Class Scaphopoda: toothed shells), coiled
conical (Class Gastropoda: snails and slugs), hinged (Class Bivalvia: clams, oysters,
scallops), internal (Class Cephalopoda: chambered nautiluses, octopuses, squids).

Phylum Echinodermata (Sea Stars)

Phylum Echinodermata is an exclusively marine group that includes the sea stars, sea
cucumbers, sea urchins, brittle stars, sand dollars, and sea lilies. You will see
representatives of the classes Asteroidea (sea stars) and Echinodea (sea urchins). Many
other echinoderms have the ability to regenerate lost limbs and have a unique water
vascular system which is essential for respiration, locomotion, capture of prey, and
attachment.




                                             5
Phylum Chordata (Chordates)

Chordates make up a tight evolutionary group that encompasses three subphyla, which
includes vertebrata, of which humans are a part. The most numerous vertebrates are the
fish.

Subphylum: Urochordata (Tunicates)

Subphylum: Cephalachordata (Lanclet)

Subphylum: Vertebrata (fish, amphibians, reptiles, birds, mammals)

All of these subphyla are linked by having, either in adult and/or fetal form, the following
characteristics:

a) Notochord

b) Dorsal Hollow Nerve Cord

c) Post-anal Tail

d) Pharyngeal Slits




                                             6
Lab Report                                            Name:
Kingdom Protista

What characteristics define this Kingdom?


What is the importance of this group to understanding the evolution of the
Kingdom Animalia?




Observe Volvox under the microscope.
Describe what you see. What is this organism composed of?




Why is this organism green in color?




Observe the Paramecium.
Describe how this organism moves around?




How does this organism gain nutrition?




                                         7
Kingdom Animalia

Phylum Porifera

What characteristics define this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Look closely, describe the level of organization (cell, tissue, organs) is present in
this phylum?




Phylum Coelenterata

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Look in the microscope at the Hydra (Class Hydrozoa).
How does it move around?



Describe how it captures food?



How is the Hydra similar and dissimilar to the sea jellies (Class Scyphazoa) and
anemones (Class Anthozoa) on display?



                                          8
Phylum Platyhelminthes

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Observe the free-living flatworms (Class Turbellaria).
How do they move about?



How do they acquire nutrients?


What are the two dark spots are the head?



Look at the preserved specimen of the Class Cestoda.
What is the common name for this animal?




How does Cestoda reproduce?




Describe two ways in which Cestoda differs from Turbellaria?




                                         9
Phylum Nematoda

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Observe the specimen of Ascaris.
How does this animal acquire nutrients?




Phylum Annelida

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Observe the earthworm (Class Oligochaeta).
How does it move?



How does it gain nutrients?


Look at its internal anatomy.
How many hearts does it have?


Does it have a brain?



                                      10
Phylum Mollusca

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Observe the anatomy of a octopus (Class Cephalopoda).
What characters tie these animals together?



How do they move about?




Observe the anatomy of the clam (Class Bivalvia).
Why are these animals called bivalves?



Describe how they move about?



How do they gain nutrition?



Observe the snails (Class Gastropoda).
What types of habitats do they live in?
Describe how they move around?


How do they gain nutrients?




                                      11
Phylum Arthropoda

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




Observe the specimens of Class Arachnida.
What is anatomically unique about them compared to other arthropods?



Observe the centipede (Class Chilopoda)
What is anatomically unique about them compared to other arthropods?



Observe the crayfish (Class Malacostraca).
What is unique about the crayfish compared to other arthropods?



Observe the grasshoppers (Class Hexapoda).
What is unique about them compared to other arthropods?




Describe the similarities and differences between crayfish and grasshoppers?




                                      12
Phylum Echinodermata

What characteristics are unique to this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




How does this animal move about? Describe how the water vascular system
works.




Considering the symmetry of adult echinoderms, explain how and why this is
considered the ancestor to the Phylum Chordata.




Phylum Chordata

What defines this Phylum?



What type of body plan (coelom formation, symmetry, body cavity) is exhibited by
this phylum?




                                      13
What are the four characteristics that link the animals in this phylum together?




Observe the slide of the subphylum Cephalochordata (lancelet) and find all four
characteristics of the phylum.




Observe the specimens of the subphylum Vertebrata. List the characteristics
unique to each class of vertebrates:

Fishes:



Amphibia:



Reptilia:



Aves:



Mammalia:




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