General Biology II Lab
Lab #6: Introduction to the Kingdom Animalia
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OBJECTIVES:
1.
2.
3.
4.
5.
6.
Understand hierarchical organization of animal complexity.
Learn the differences between acoelomate, pseudocoelomate and coelomate organisms.
Learn the advantages of cellular specialization to form tissues and organs.
Learn how to classify organisms based on body symmetry.
Understand the major differences between protostomes and deuterostomes.
Learn and employ the directional terms used to identify body positions on different types
of organisms.
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INTRODUCTION:
The multicellular organisms that make up the 32 phyla of Kingdom Animalia have
evolved from the nearly 100 phyla produced during the Cambrian explosion about 600 million
years ago. During this time, an unprecedented variety of novel body plans and architectures arose
(Fig. 1).
Figure 1. Diversity of members belonging to the Animal Kingdom
In the upcoming labs, we will examine the different levels of complexity and organization in
representative phyla of Kingdom Animalia (See Fig. 2). We will consider the environmental
constraints that led to the evolution of particular body plans and the adaptations that certain
animals evolved in order to survive in their respective environments.
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In general, members of Kingdom Animalia are eukaryotic, multicellular, motile (at least
during certain developmental stages), heterotrophic and unlike plants, lack a cell wall.
Additionally, most animals reproduce sexually and have a characteristic pattern of embryonic
development. Similar to alternation of generations observed in previous phyla, organisms in the
Animal kingdom undergo stages of development, starting from the fusion of an egg and a sperm
and ending with a multicellular adult phase. While the morphology of the adult organism is
highly species-specific, the genes that regulate organismal development are often conserved
across species. In addition, the life cycles of members of Kingdom Animalia vary considerably,
i.e., the stages may look completely different from each other (metamorphosis), they may last
for different periods of time (hours vs. years) and can occur in different habitats (e.g. dragonflies
- adults live in air while larvae are aquatic).
Figure 2. Phylogenetic tree of members of Kingdom Animalia
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Task 1: Understanding the hierarchical organization of animal complexity
The common descent of animals within Kingdom Animalia can be observed in the
organization of body plans and the fundamental building blocks that all animals share. Unique
and shared characteristics among members of the animal kingdom are convincing evidence that
the group is monophyletic (i.e. a group that shared a common ancestor and all its members). The
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hierarchiral level of organization of animals is cell, tissue, organ and organ system. Animalia is
divided into two main branches—the Parazoa and the Eumetazoa. Parazoans, like sponges,
mostly lack any true symmetry and tissues. Eumetazoans, on the other hand, have definite
symmetry and tissues. Most eumetazoans have complex arrangements of cells and tissues into
organs and organ systems. The nerve net of jellyfish is a good example of cell-tissue
organization (Fig. 6.3).
Following in complexity is the tissue-organ level of organization, produced when
different types of tissues combine to form organs. In general, organs perform more specialized
and complex functions than tissues and can be composed of different tissue types (e.g. the heart,
which is composed of cardiac muscle, epithelial, connective and nervous tissues). This level of
organization is observed exclusively in eumetazoans, most of which also exhibit an organ-system
level of organization, where multiple organs operate together, forming a system that has a
specific function (Fig. 3). In eumetazoans, there are eleven organ systems: skeletal, muscular,
integumentary, digestive, respiratory, circulatory, excretory, nervous, endocrine, immune and
reproductive. We will examine some of these systems in greater depth during Labs 8-11.
Figure 3. Hierarchical organization
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The major patterns of organization of animal complexity are described below in Table 1.
As you examine the organisms today, note which level of organization is present in each. Make
sure to sketch the organisms listed for each level of organization, noting the phylum, genus and
species of each.
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Task 1: Understanding the hierarchical level of organization of animal complexity
Table 6.1
Level of
organization
Cellular
Cell-tissue
Tissue-organ
Organsystem
Description
Aggregation of
cells that are
functionally
differentiated.
Cells are
aggregated into
patters/layers =
tissues.
Different tissues
are organized into
organs; more
specialized than
tissues.
Organs work
together as a
system to
perform a
coordinated
function
Representative
group
Parazoa
Radiata
Bilateria
Bilateria
a. Porifera
b. Grantia
c. Sponges
a. Cnidaria
b. Metridium
c. Sea anemone
a. Platyhelminthes
b. Dugesia
c. Planarian
a. Chordata
b. Perca
c. Perch
Example:
a. phylum
b. genus
c. common name
Drawing of
whole organism
Note: Do NOT dissect the Planarian or the Perch!
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Questions:
1.
Can you suggest why, during the evolution of separate animal lineages, there has been a
tendency for complexity to increase when body size increases?
2.
Sponges have folded walls. What advantage could this trait have for the sponge?
3.
What other organisms or organ systems possess similar folded structures?
a. What advantages does folding provide for these organisms?
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Task 2: Differentiating between acoelomate and coelomate organisms
A major developmental event in bilaterally symmetrical organisms (see Task 3) was the
development of a fluid filled cavity (coelom) between the outer body wall and the gut. The
coelom created a tube-within-tube arrangement allowing space for visceral organs and an
increase in overall body size (Why?). This structure also provides support and aids in
movement/burrowing in some animals. However, not all organisms are coelomates; some lack a
coelom altogether and are called acoelomate (a = without) while others are characterized by a
pseudocoelom (pseudo = false). All three types of body cavities are illustrated below in Figure
4.
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Figure 4. Types of body cavities
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7
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Examine the organisms listed in Table 2 and complete the missing sections.
Table 6.2
Sample Organism
Phylum
Acoelomate
Platyhelminthes
Pseudocoelomate
Nematoda
Coelomate
Annelida
Genus
Dugesia
Ascaris
Lumbricus
Common name
Flatworms, planaria
Roundworms
Segmented worms,
Earthworms
Drawing of
Cross section
(slide)
Only dissect the
Ascaris, the rest
you can just draw
as a whole
organism
Questions:
1. Looking at the three representative specimens, what is the main difference between
coelomate, pseudocoelomate and acoelomate organisms?
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2. How are the organs and tissues organized differently in coelomates and acoelomates?
3. Is the Ascaris you dissected, male or female?
a. How can you tell?
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Task 3: Body plans and symmetry
While the diversity of animal forms is great, the basic body plans can be categorized by
the presence and type of body symmetry (Fig. 5). Symmetry refers to the correspondence in size
and shape between opposite sides of an organism’s body. Sponges, which lack body symmetry,
are considered asymmetrical whereas animals whose bodies are arranged around a central axis
and can be divided by more than two planes along the longitudinal axis exhibit radial symmetry.
This primitive type of symmetry evolved amongst members of phylum Cnidaria (sea anemones,
box jellies, jellyfish and hydra) and Ctenophora (comb jellies). The bodies of the more
evolutionarily advanced bilaterians, in contrast, can be divided into right and left halves along a
sagittal plane. Make sure you understand the basic differences between the three types of
symmetry.
Figure 5. Types of symmetry
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Compare and contrast the different types of symmetry by examining the animals listed for each
type in Table 3. Answer the questions that follow.
Table 6.3
Symmetry type
Asymmetrical
Example Phyla/Species
Drawing
Sponge
Radial
Sea anemone
Bilateral
Perch
Description
Questions:
1. In what kind of environment would each type of body symmetry would be most efficient?
2. What is the advantage of having bilateral symmetry? Can any particular task be achieved
more efficiently?
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a. Why would this type of symmetry lead to cephalization?
3. Out of all the organisms you examined, is there a particular pattern between the
organisms that have bilateral symmetry? Radial symmetry? Make sure to consider
morphology.
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Task 4: Developmental patterns in bilateral animals: Protostomes vs. Deuterostomes
Bilateral animals follow two major patterns of embryonic development. Based on these
patterns, they are classified as either deuterostomes or protostomes. In deuterostomes, the
blastopore (first embryonic opening) becomes the anus, while in protostomes the blastopore
becomes the mouth. Also, cleavage, the initial process of cell division after a zygote is formed,
differs in the two lineages; in protostomes, cleavage is spiral while in deuterostomes, it is radial
(Fig 6).
The separation of the metazoans (multicellular animals) into two separate lineages,
suggests an evolutionary divergence of the bilateral body plan. This suggests that deuterostomes
and protostomes are separate, monophyletic lineages (See Fig 2).
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Examine the animals noted under the “Example species” row in Table 4.
Table 6.4
Cleavage type
Blastopore
becomes
Representative
Phyla
Example species
Protostomes
Spiral
Mouth
Deuterostomes
Radial
Anus
Platyhelminthes, Arthropoda,
Annelida, Mollusca, Nematoda, and
smaller phyla
Chordata, Echinodermata, and
smaller phyla
Nematoda - Ascaris
Sea star – Asterias
Drawing
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Task 5: Describing positions in bilaterally symmetrical animals
For a large portion of this course you will be examining bilaterally symmetrical animals
from various phyla. You must understand that these terms differ depending on which organism
you’re referring to, a biped or a quadruped. A biped, such as a human, is an animal that walks
only on its hind limbs while a quadruped, such as a rat, is an animal that walks on all fours. To
be able to locate and refer to specific regions of animal bodies, we will use terminology listed in
Table 6.5 and 6.6.
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Table 6.5
Direction
Relative to front (belly side) or
back (back side) of the body
Term
Anterior
Posterior
Dorsal
Ventral
Superior
Relative to the head or tail of the
body
Inferior
Caudal
Cranial
Rostral
Relative to the midline or center of Medial
the body
Lateral
Proximal
Relative to point of attachment of
the appendage
Distal
Meaning
In front of; toward the front surface
In back of; toward the back surface
At the back side of the human body
At the belly side of the human body
Closer to the head
Closer to the feet
At the rear or tail end
At the head end
Toward the nose
Toward the midline of the body
Away from the midline of the body
Closest to point of attachment to trunk
Furthest from point of attachment to
trunk
Table 6.6
Anterior
Posterior
Superior
Inferior
Biped
Belly side; Ventral
Back side; Dorsal
Closer to the head
Closer to the feet
Quadruped
At the head; Cranial
At the tail; Caudal
Not used
Not used
Figure 6.12 Directional Terms
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Sagittal
plane
Frontal
plane
Transverse
plane
Frontal
plane
Sagittal
plane
Transverse
plane
Figure 6.13A: Biped Planes
Planes
Frontal Plane
Figure 6.13B: Quadruped Planes
Biped
Divides the body into dorsal
and ventral halves
Divides the body into anterior
and posterior halves
Divides the body into left and
right halves
Transverse Plane
Sagittal Plane
Quadruped
Divides the body into dorsal
and ventral halves
Divides the body into anterior
and posterior halves
Divides the body into left and
right halves
Practice, practice, practice! Using the words in the boxes for each section, complete the
sentences.
PART A:
Anterior
Posterior
Dorsal
Ventral
1. The heart is ________________ to the sternum.
2. The belly button is on the ______________ side of the body.
3. The stomach is ______________ to the spinal cord.
4. The spinal cord is on the _______________ side of the body.
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PART B:
Superior
Inferior
Caudal
Cranial
Rostral
1. The feet are _____________ to the head.
2. The head is _______________ to the ankle.
3. The chest is _______________ to the pelvis.
4. The stomach is ____________ to the heart.
5. The frontal lobe is ____________ to the occipital lobe.
PART C:
Medial
Lateral
1. The arms are ____________ to the heart.
2. The lungs are ____________ to the shoulders.
PART D:
Proximal
Distal
1. The elbow is _____________ to the wrist.
2. The fingers are _____________ to the elbow.
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Task 6: Body axes charades – Run by your TA
To practice using the correct terminology when referring to different locations on the
body, you will play a game of charades. Your TA will divide the whole class into two groups.
One student from the first group will go up and pick a card at random. The student will
have 1 minute to describe the word to his/her group, using ONLY the anatomical terms on
Table 6.5. Note that you cannot use words that describe the function of the organ/body part. For
example, if the organ to be described is the heart, you are not allowed to say that it pumps blood.
Instead, you can say that it is inferior to the head and it is superior to the belly button. If his/her
group can guess the right answer, then that team gets a point but if they don’t guess correctly,
then the opposite team gets the point. Make sure to alternate the order of the teams guessing.
Each person in each group should take a turn. Make sure not to point at any of your body parts!
Have fun and be good sports! 
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