BSC 2011L – Principles of Biology 2 Lab
Lab Topic 18 – Animal Diversity I
Porifera, Cnidaria, Platyhelminthes, Mollusca and
Annelida
Lab Topic 18: Animal Diversity I
• After completing this lab topic, you should
be able to:
– 1. Compare the anatomy of the representative
animals, describing similarities and differences in
organs and body form that allow the animal to
carry out body functions.
– 2. Discuss the impact of molecular studies on
traditional phylogenetic trees.
– 3. Discuss the relationship between body form
and the lifestyle or niche of the organism.
Introduction
• Animals are classified in the Domain
•
•
•
•
•
Eukarya, Kingdom Animalia (clade
Metazoa)
Animals are multicellular and
heterotrophic (food is ingested)
Animals are thought to have arisen ~575
million years ago
Most body forms appeared by the end of
the Cambrian period
35 major groups are recognized based on
body form
In lab topics 18 and 19, we will look at nine
major animal groups
Introduction
• Parazoa – includes the sponges
• Eumetazoa – includes all other animals
• Symmetry
– Radial – parts arranged around a central axis
– Bilateral – right and left halves are mirror
images
• Other physical characteristics
– Type of body cavity (coelom)
– Embryological differences
• Number of germ layers
• Development of the digestive tract
(a) Radial symmetry
(b) Bilateral symmetry
Coelom
Digestive tract
(from endoderm)
Body covering
(from ectoderm)
Tissue layer
lining coelom
and suspending
internal organs
(from mesoderm)
(a) Coelomate
Body covering
(from ectoderm)
Pseudocoelom
Muscle layer
(from
mesoderm)
Digestive tract
(from endoderm)
(b) Pseudocoelomate
Body covering
(from ectoderm)
Tissuefilled region
(from
mesoderm)
Wall of digestive cavity
(from endoderm)
(c) Acoelomate
Protostome development
(examples: mollusks,
annelids)
Deuterostome development
(examples: echinoderm,
chordates)
Eight-cell stage
Eight-cell stage
Spiral and determinate
(a) Cleavage
Radial and indeterminate
(b) Coelom formation
Key
Coelom
Ectoderm
Mesoderm
Endoderm
Archenteron
Coelom
Mesoderm
Blastopore
Blastopore
Solid masses of mesoderm
split and form coelom.
Mesoderm
Folds of archenteron
form coelom.
Anus
Mouth
(c) Fate of the blastopore
Digestive tube
Mouth
Mouth develops from blastopore.
Anus
Anus develops from blastopore.
Common ancestor
of all animals
Metazoa
Sponges
(basal animals)
Eumetazoa
Ctenophora
Cnidaria
Acoela (basal
bilaterians)
Deuterostomia
Bilateral
symmetry
Three germ
layers
Lophotrochozoa
Ecdysozoa
Bilateria (most animals)
True
tissues
“Porifera”
Metazoa
Calcarea
Ctenophora
Eumetazoa
ANCESTRAL
COLONIAL
FLAGELLATE
Silicea
Cnidaria
Acoela
Bilateria
Deuterostomia
Echinodermata
Chordata
Platyhelminthes
Lophotrochozoa
Rotifera
Ectoprocta
Brachiopoda
Mollusca
Annelida
Ecdysozoa
Nematoda
Arthropoda
Introduction
• Protostomes
– Lophotrochozoa
• Trochophore larvae (annelids, molluscs,
flatworms)
– Ecdysozoa
• Roundworms (nematodes) and arthropods
• Animals undergo molting of cuticle (nematodes) or
exoskeleton (arthropods)
• Comparative study of organisms
– Consider symmetry, tissue organization, body
cavity, openings into the digestive tract,
circulatory system, habitat, organs for
respiration, organs for excretion, type of
locomotion, support systems, segmentation,
appendances, and type of nervous system
Ecydsis
Lophophore
Apical tuft
of cilia
100 µm
Mouth
(a) An ectoproct
Anus
(b) Structure of a trochophore
larva
Exercise 18.1 – Phylum Porifera
• Sponges (Scypha)
• Materials
– Dissecting needle
– Compound and stereoscopic microscopes
– Preserved and dry sponges
– Prepared slide of Scypha in longitudinal
section
– Preserved Scypha in watch glass
• Introduction
– Within the Animal Kingdom, sponges are
separate from all other animals due to their
unique body form
– We will observe several sponge specimens
Exercise 18.1 – Phylum Porifera
• Procedure
– Follow the procedures in your lab manual
• Results
– Complete summary Tables 19.1 and 19.2 in
Lab Topic 19
– Make sure to fill in all of the information on
sponge characteristics
– Also refer to your textbook and the pictures I
have inserted in the lab topic outline slides
Sponge Body Plan
15
Cells that make up the sponge body
16
The Sponge Scypha
17
The encrusting sponge Amphimedon compressa
18
The yellow tube sponge Aplysina fistularis
19
The vase sponge Callyspongia plicifera
20
The tube sponge Callyspongia vaginalis
21
The stinking vase sponge Ircinia campana
22
The Bahamian loggerhead sponge Ircinia strobilina
23
The orange icing sponge Mycale laevis
24
The giant barrel sponge Xestospongia muta
25
Exercise 18.2 – Phylum Cnidaria
• Hydras (Hydra)
• Materials
– Stereoscopic and compound microscopes
– Living Hydra and water flea cultures
– Dropped bottles of water, acetic acid, and
methylene blue
– Prepared slide of Hydra sections
– Slides and cover slips
• Introduction
– Cnidarians are a diverse group that have a
tissue grade of organization
– No complex organs, but two body forms
present in the life cycle: medusa and polyp
Exercise 18.2 – Phylum Cnidaria
• Procedure
– Follow the procedures in your lab manual
• Results
– Complete summary Tables 19.1 and 19.2 in
Lab Topic 19
• Discussion
– What major differences have you detected
between Scypha and Hydra body forms? List
and describe them.
Generalized Cnidarian Life Cycle
28
The solitary freshwater Hydra
29
Box Jellyfish
30
The stinging anemone Lebrunia danae
31
The black coral Antipathes
32
The colonial zoanthid Palythoa
33
Sea plumes (Pseudopterogorgia americana)
34
Exercise 18.3 – Phylum Platyhelminthes
• Planarians (Dugesia)
• Materials
– Stereoscopic and compound microscopes
– Living planarian and watch glass
– Prepared slides of whole mount of planarian
and cross sections
• Introduction
– The Phylum Platyhelminthes (clade
Lophotrochozoa) includes planarians, which
are free-living flatworms
– The body is dorso-ventrally flattened
– Body movement is accomplished by muscles
in the body wall and cilia on their ventral
sides
Exercise 18.3 – Phylum Platyhelminthes
• Procedure
– Follow the 5-step procedure in your lab manual
• Results
– Diagram the flatworm as seen in a cross section
at the level of the pharynx. Make sure to label the:
• Epidermis
• Muscle derived from mesoderm
• The lining of the digestive tract derived from endoderm
• The pharynx
• The pharyngeal gill chamber
– Complete summary table 19.1 in Lab Topic 19
• Discussion
– One of the major differences between Cnidaria
and Platyhelminthes is radial versus bilateral
symmetry. Discuss the advantage of radial
symmetry for sessile animals and bilateral
symmetry for motile animals.
A Planarian
37
Platyhelminthes
(flatworms)
38
Exercise 18.4 – Phylum Mollusca (Clams)
• Materials
– Dissecting instruments and dissecting pan
– Preserved clam or mussel
• Introduction
– Phylum Mollusca (clade Lophotrochozoa) are
second only to the arthropods in diversity
– Most species are marine and several are of
economic importance
– Includes diverse animals such as snails,
slugs, clams, squids, and octopuses
– Most share four characteristic features:
internal or external shell, the mantle which
secretes the shell, a visceral mass, and a
muscular foot
Exercise 18.4 – Phylum Mollusca
• Procedure
– Follow the procedures in your lab manual
– Be sure to answer all questions as you
observe the clam
• Results
– Complete summary Tables 19.1 and 19.2 in
Lab Topic 19
• Discussion
– List several features of clam anatomy that
enable it to survive in a marine environment.
Mollusk Body Plans
41
Oyster Life Cycle
Clams in the Phylum Mollusca
43
Exercise 18.5 – Phylum Annelida
• Lab Study A. Clamworms (Nereis)
– Materials
• Dissecting tools and pins, dissecting pan
• Preserved clamworm
– Introduction
• Species of Nereis (clamworms) are common in
mud flat environments and on the ocean floor
• They burrow in sediments during the day and
emerge at night to feed
• As you observe the clamworm, note features that
are characteristic of all annelids, as well as
features that are special adaptations to the marine
environment
Exercise 18.5 – Phylum Annelida
• Lab Study A. Clamworms (Nereis)
– Procedure
• Follow the 10-step procedure in your lab manual
• Make sure to answer the questions in this section
as you observe the clamworm
– Results
• Complete summary Tables 19.1 and 19.2 in Lab
Topic 19 for the clamworm characteristics
Clamworms (Nereis)
46
Exercise 18.5 – Phylum Annelida
• Lab Study B. Earthworms (Lumbricus)
– Materials
– Introduction
– Procedure
– Results
• Complete summary Tables 19.1 and 19.2 in Lab
Topic 19 for the earthworm characteristics
– Discussion
• A major new feature observed in the Phylum
Annelida is the segmented body. Speculate about
possible adaptive advantages provided by
segmentation.
Earthworms (Lumbricus terrestris)
48
Lab Topic 18: Animal Diversity I
• Reviewing Your Knowledge
– Answer questions 1-3 on page 488 in the lab
manual
– Make sure to complete Tables 19.1 and 19.2 in
lab topic 19 for the animals observed in lab
topic 18
• Applying Your Knowledge
– Answer the one question on Hydra on page
489 in the lab manual