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Lab: Kingdom Animalia – Animal Diversity
BIOL212 Lab
1
Name:
Kingdom Animalia (select phyla)
OBJECTIVES:
• Identify organisms from 9 select animal phyla and recognize some of their major characteristics.
• Understand the following terms and recognize examples of each: diploblastic, triploblastic, endoderm,
ectoderm, mesoderm, acoelomate, pseudocoelomate, coelomate, cephalization, segmentation
• Compare bilateral and radial symmetry in body plans
• Identify some cell types present in the body of a sponge
• Compare the forms (polyp and medusae) of Cnidarians
• Classify bilateral organisms as Lophotrochozoans, Ecdysozoans, or Deuterostomes.
• Understand the difference between a protostome and a deuterostome
• Distinguish a free-living vs. parasitic life style (and body plan)
• Understand the body plan of a typical mollusk, and recognize the differences between major mollusk groups
• Understand the body plan of a typical arthropod, and recognize the differences between major arthropod
groups
• Recognize the major characteristics of echinoderms
• Recognize the 4 chordate characteristics
• Compare adaptations to living aquatic vs. terrestrial lifestyles
INTRODUCTION
In this Lab exercise, we will examine the Kingdom Animalia. Organisms in the Animal Kingdom are all
multicellular, heterotrophic, eukaryotes. In the Domain classification system, they are classified in the
Domain Eukarya along with the Protists, Fungi, and Plants. Animals are thought to have evolved more than 500
million years ago, as they branched from a group of Protistans called the Choanoflagellates. Throughout the
course of our examination, we will explore a select group of representative phyla in the kingdom. We may
discuss several other phyla during lecture, but not look at them in the lab activities.
We will also be following several trends in our study of the Animal Kingdom. These include (but are not limited
to): body symmetry, presence of body cavities, digestive tracts, circulatory systems, nervous, respiratory,
excretory, and reproductive organs, locomotory structures, cephalization, segmentation, and support systems.
We will also examine some of the specific structures in the organisms we view during lab.
We will examine several phyla from the Kingdom Animalia in our “story” of animal diversity. For each phylum, we
will examine a combination of prepared specimens and slides. The Laboratory Guides (Zoology or Biology) will
be very helpful in guiding you through this lab. Basic information for the select phyla will be provided in lecture
and is also in your textbook.
STUDENT PREPARATION AND GENERAL LAB PROCEDURES FOR THIS LAB.
Prepare for this laboratory by reading the text pages indicated by your instructor. Familiarizing yourself in
advance with the information and procedures covered in this laboratory will give you a better understanding of
the material and improve your efficiency. As you work your way through this Kingdom, you will examine many
specimens and some slides. For each organism you view under the scope, you should draw and label the
specimen. When you label the drawings, be sure to include all the structures that you can identify on the
specimen and the total magnification you used.
Select Phyla of the Kingdom Animalia
I. Phylum Porifera (sponges) – see Fig. 33.4 in Campbell text.
Background: The sponges are the least complex of all multicellular animals. They are asymmetrical, lack true
tissues and do not have organs. In fact, if the cells of a sponge are separated, the cells become amoeboid and
reaggregate and redifferentiate into a new sponge without regard to their previous roles.
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The body of a sponge is organized around a system of water canals. Water is drawn through small pores into a
central cavity, the spongocoel, and then flows out through a larger opening, the osculum. Cells of the sponge
body are differentiated by function. Flattened epithelial cells cover the outer surface. On the inner surface,
specialized cells called choanocytes or “collar cells” create a current that draws water into the cells where fine
food particles stick to the surface and are digested, thus serving in filter-feeding. In the middle jellylike layer,
wandering amoebocytes secrete a skeleton composed of calcium carbonate (CaCO3), silicon dioxide (SiO2), or
a protein called spongin. Calcareous and siliceous sponges are hard due to the presence of tiny rod-like skeletal
elements called spicules. The natural sponges you might buy for bathing or to wash your car are soft and are
made of a skeletal network of spongin fibers.
Most sponges are marine, but a few live in fresh water. As adults, all are sessile (attached to a substrate). They
can reproduce asexually by budding or fragmentation and sexually by production of eggs and sperm. Most
sponges are hermaphroditic (or monoecious); each individual has both male and female gonads. The zygote
develops into a free-swimming, flagellated larva—free-swimming hollow ball of flagellated cells that resembles
the embryonic blastula of other organisms. When the larva settles and attaches to a substrate, the external cells
lose their flagella and move to the interior in a process of cellular reorganization much like that of gastrulation in
other animals.
Terms to know and structures to identify: spongocoel, osculum, epithelial cells, choanocytes, amoebocytes,
spicules, sessile
· Microscope Slides: Leucosolenia (w.m.), spicules
· Prepared Specimens: Preserved and dried sponges (Grantia, Chalina, Euspongia, Leucosolenia, Spongilla)
II. Phylum Cnidaria (“stinging” Animals) See Figs. 33.5 and 33.6, text
Background: Organisms in the phylum Cnidaria have distinct cell layers and are radially symmetrical. Symmetry
implies a higher degree of complexity and organization than the asymmetrical organization characteristic of the
sponges. Cnidarians are diploblastic (2 embryonic tissue layers – ectoderm and endoderm), and the body
contains a gastrovascular cavity that is responsible for digestion, circulation and excretion of particles into and
out of the body. The Cnidarians are carnivores, and are named for their specialized stinging cells, the
cnidocytes, located on their tentacles. Some specialized cnidocytes have exploding, threadlike nematocysts
that penetrate into their prey like harpoons! These animals have basic contractile tissues with movement
coordinated by a simple nerve net. Cnidaria have two main body types, the medusa and polyp.
Terms to know and structures to identify: radial symmetry, cnidocyte, nematocyst, polyp, medusa,
gastrovascular cavity, diploblastic
· Microscope Slides: budding Hydra (w.m), Obelia medusa (w.m), Obelia hydroid w/ polyps (w.m.)
· Prepared Specimens: hydras (Obelia, Polyorchis, Gonionemius, and Physalia), jellyfish (Aurelia), preserved
and dried corals (various species), sea anemones (Metridium)
All remaining phyla of animals in lab consist of organisms that are triploblastic and possess bilateral
symmetry at some time in their life history. The representatives of these diverse phyla considered in this
exercise exhibit many important evolutionary advances. One of these is the mesoderm, a third distinct
embryonic tissue layer between the ectoderm and endoderm (hence the term triploblastic). Our study of these
phyla will reveal additional advances in organization and function.
The Lophotrochozoans
Animals in the Phyla Platyhelminthes, Mollusca, and Annelida belong to this clade. All share DNA similarities
and have specialized ciliated structures (called lophophores and trochophores) in their larval forms (see Fig.
32.13).
III. Phylum Platyhelminthes – see Figs. 33.10, 33.11 and 33.12
Background: “Flatworms”—flattened, unsegmented worms—include planarians (class Turbellaria), flukes
(class Trematoda), and tapeworms (class Cestodea). They are acoelomate (lack a coelom), with body organs
embedded in their mesodermal tissues. Platyhelminthes exhibit the first extensive organ-system level of
development.
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Free-living flatworms, the turbellarians, are small, and most are marine, living on or in the bottom sediments.
Locomotion is by cilia and, in some larger flatworms undulating muscular movements may help. The nervous
system includes a small anterior ganglionic “brain” and longitudinal nerve cords. “Eyespots” consist of
concentrations of pigment (melanin) that shade photoreceptive neurons. The turbellarian digestive tract is a
gastrovascular cavity, a blind sac with no anus. The mouth is used for both ingestion and egestion.
Turbellarians are hermaphroditic and larvae are free-swimming.
Adult flukes, the trematodes, are all parasites, either internal or external. Flukes are flattened and have a ventral
sucker or other adhesive organ for attaching to their host. In some trematodes, a second sucker is associated
with the anterior mouth. Most flukes are hermaphroditic. The life cycle may involve one to four hosts—
intermediate hosts (hosts that harbor the immature stages) may be invertebrates, but the definitive host (the host
that harbors the sexually mature stage) is always a vertebrate.
Tapeworms, the cestodes, are internal parasites of vertebrates and are highly adapted for a hostile environment,
where they nonetheless enjoy a rich food supply provided by their host. They have neither a mouth nor a
gastrovascular cavity, but instead absorb nutrients directly through their body from their host! Like flukes,
tapeworms are hermaphroditic, and their life cycle may involve an intermediate host in which a “bladder worm”
stage encysts, awaiting ingestion by the definitive host. Their anterior “head” is modified into a scolex with many
hooks for attaching to the host. Reproduction is via specialized segments called proglottids.
Terms to know and structures to identify: acoelomates, pharynx, eyespots (ocelli), scolex, proglottids,
bilateral symmetry, triploblastic
· Microscope Slides: Planaria (w.m.) note pharynx, eyespots; Taenia (w.m.) – protoglottids, scolex
· Prepared Specimens: Planaria (Dugesia), Fasciola hepatica, Fasciolopsis, Taenia, Dipylidium, and Moniezia
IV. Phylum Mollusca – see pages 677-681, Campbell text
Background: Molluscs (mollusks) represent the second largest phylum, consisting of more than 93,000 living
species of marine, freshwater, and terrestrial animals. They are bilaterally symmetrical and apparently
unsegmented.
The general body plan of a mollusc includes three regions: the head – foot (used in locomotion and food
capture), the visceral mass (containing the major organ systems), and the mantle (soft tissue that secretes the
calcium-containing shell present in most molluscs).
Molluscs have an open circulatory system with a chambered heart (one ventricle and two atria) and their blood
contains an oxygen-carrying respiratory pigment, hemocyanin. Excretory organs, the metanephridia, drain the
relatively small coelom surrounding the heart and a portion of the intestine. Gills are present in the mantle cavity
of most molluscs. Molluscs may be filter-feeders, sediment-feeders, herbivores, or carnivores. Many mollusks
use a radula, a rasp-like organ, to scrape food.
Molluscs with shells include species that have several shell plates (chitons), hinged shells (bivalves—including
clams, oysters, and scallops), conical twisted shells (gastropods—including snails), and reduced or internalized
shells (cephalopods—including squids and octopi – note that octopi lack a shell altogether).
Terms to know and structures to identify: mantle, shell, visceral mass, foot, head, radula, coelomate,
· Microscope Slides: snail radula (2 types in slide box – may want to look at both!)
· Prepared Specimens: Helix (land snail), Dendronotus (sea slug), limpets, Limax (land slug), chiton, Katherina
(marine clam), squid
· Fresh specimens: clam and/or mussel (depending on availability)
V. Phylum Annelida – see Figs. 33.23, 33.24 and 33.25, Campbell text
Background: Phylum Annelida contains the segmented worms, almost all of which are free-living.
The coelom of annelids is compartmentalized into segments by septa. Coelomic fluid within the body cavity
acts like a hydrostatic skeleton against which muscles work to change body shape. Like nematodes, annelids
have a one-way digestive tract with a mouth, anus, and several specialized regions.
A dorsal mass of nerve cells forming a ganglion or “brain” and a ventral nerve cord provide a primitive nervous
system. The circulatory system is closed, blood being confined to blood vessels.
Marine polychaetes (sand worms), oligochaetes (freshwater annelids and earthworms), and leeches are among
the most common annelids. There are over 8,700 known species of annelid worms.
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Many oligochaetes such as the earthworm have taken up a terrestrial life but have not completely adapted to
land; they secrete a thick mucus to keep their skin moist and must remain within their damp burrows in the
ground unless the surface is soaking wet. They eat soil and decaying vegetation and have a well-developed
complete digestive system to process their vegetarian diet. Earthworms occur in the soil in large numbers and
are extremely important in maintaining the soil’s loose, aerated condition, because they process their body
weight in soil each day.
The earthworm’s head is much reduced to adapt to its burrowing way of life. As an oligochaete (“few bristles”), it
has only four pairs of chaetae (setae) on each segment for traction instead of the parapodia found in
polychaetes. Gas exchange takes place over the entire moist body surface and is aided by an efficient closed
circulatory system in which the blood, containing hemoglobin, is moved by 10 little pumps (“hearts”).
The individual earthworm is hermaphroditic, producing both eggs and sperm, but copulates with another worm
rather than fertilizing itself.
The polychaetes (= “many bristles”) make up the largest group of annelids. Most are marine and are an
important food source for fish and crustaceans. Polychaetes have parapodia, fleshy appendages on the body
segments. Chaetae are found on the parapodia. The polychaetes have well-developed sense organs on their
heads, including eyes, antennae, and chemoreceptors. Some polychaetes build tubes in which to live. Many of
these sedentary forms use tentacles covered with cilia to trap food such as tiny animals and decaying organic
matter and transport it to the mouth. Others pump water through their burrows and filter food from the water.
Most leeches (class Hirudinea) live in fresh water. They are parasitic or predaceous, feeding on tissue fluids,
blood, or small invertebrates. Leeches lack the chaetae characteristic of other members of the phylum. Terms to
know and structures to identify: segmentation, septa, chaetae (setae), parapodia
· Microscope Slides: Leech (Hirundo sp.) note segmentation
· Prepared Specimens: Nereis sp., Amphritite sp., Lumbricus sp. (earthworm), Haemopis sp. (leech)
The Ecdysozoans
Animals in this clade, including Phylum Nematoda and Phylum Arthropoda, produce an external cuticle which is
shed as they grow, a process called ecdysis (molting). The group is substantiated by DNA evidence.
VI. Phylum Nematoda – see Figs. 32.26, 32.27, text
Background: Nematodes (roundworms) are small, generally free-living animals with an anterior mouth and
sense organs, but no well-defined head. Cilia are reduced and the body is covered with a secreted cuticle.
When the nematode grows, it molts by shedding the cuticle and forming another one to fit its larger self! The
digestive tract is usually complete and has a specialized “pharynx”. Most of these organisms have a
protonephridia. The sexes are separate (dioecious) in most of these organisms. The phylum Nematoda consists
of about 25,000 known species.
The nematodes are unsegmented worms that may be either free-living or parasitic. Many free-living forms are
inhabitants of the soil. Parasitic forms invade plant bodies and destroy tissues. Common animal parasites
include hookworms, intestinal roundworms (Ascaris), Trichinella, and pinworms.
In contrast to the acoelomate flatworms, the nematodes have a type of body cavity, a pseudocoelem which is
only partially lined by mesoderm, unlike the true coelom, found in some other phyla, which is completely lined
with mesoderm found in some other phyla. Nematodes also have a complete digestive system with two
openings—a mouth and an anus—allowing regions of the digestive tract to assume specialized functions.
Terms to know and structures to identify: pseudocoelom, dioecious, cuticle
· Demonstration Slides: Trichinella spiralis (encysted in pork)
· Prepared Specimens: Ascaris (intestinal parasite of humans)
VII. Phylum Arthropoda – see pages 684-692, text
Background: Arthropods are by far the most numerous and diverse of all animals, with more than 1 million
known species (most of which are insects)! Terrestrial, freshwater and marine forms are found in every
conceivable habitat due to their high degree of evolutionarily adaptability and their great mobility, including the
ability to fly in most insects.
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The segmented arthropod body, covered by a chitinous exoskeleton, is typically divided into three body sections:
the head, thorax and abdomen. Each of these may be subdivided into several segments to which are attached
jointed appendages that carry out a variety of functions. As arthropods grow they shed their chitinous
exoskeleton by the process of molting (ecdysis). During growth, many arthropods also undergo a marked
change in form (metamorphosis). If this is the case, the larva, a feeding stage, often bears no resemblance to
the adult organism.
The arthropod circulatory system is open: a distinct muscular heart pumps a fluid called hemolymph through
open spaces in the tissues, which are collectively called the hemocoel. The coelom, correspondingly, has been
reduced and is represented in most arthropods only by the cavity of the gonads. The digestive tract of
arthropods is well developed and modified into several distinct parts. The nervous system and associated sense
organs are particularly well-developed and control a variety of complex behaviors, including flight in winged
insects.
The group of organisms we collectively call arthropods appears to have diverged into 4 subphyla. The
subphylum Crustacea includes crabs, lobsters, shrimps and barnacles. Crustaceans have biramous (twobranched) appendages, two pairs of antennae, as well as mandibles (jaws), and a pair of compound eyes.
The subphylum Chelicerata includes spiders, mites, ticks, scorpions (Class Arachnida), and horseshoe crabs.
Chelicerates have 4 pair of walking legs and lack appendages and mandibles (jaws). Instead, the first pair of
appendages, the chelicerae, are in the forms of pincers or fangs. Members of the subphylum Hexapoda
includes the insects (Class Insecta) (insects). Insects have 3 pair of walking legs in adult form, and go through
either complete or incomplete metamorphosis during their lifetimes. Subphylum Myriopoda includes centipedes
and millipedes. The Myriopoda have 1 pair of antennae and unbranched (uniramous) appendages centipedes,
have one set of legs per body segment, and millipedes, have two sets per segment.
Terms to know and structures to identify: exoskeleton, head, thorax, cephalothorax, abdomen, chelicerae,
mandible, biramous appendages, uniramous appendages, antennae, compound eyes, jointed appendages,
metamorphosis
· Microscope Slides: Megalops (crab) (dissecting microscope); Insect cornea (compound eye)
· Prepared Specimens: numerous species of crustaceans
· Display cases of insects
· Prepared Specimens: numerous species of crustaceans, insects, arachnids, centipedes and millipedes.
· Live specimen: Rosie! an arachnid
The Deuterostomes
VIII. Phylum Echinodermata –see Fig 33.40, 33.41, text
Background: The phylum Echinodermata includes four major groups of marine bottom dwellers or burrowers:
the sea stars, brittle stars, sea urchins, sand dollars, sea lilies, and sea cucumbers are all examples.
Echinoderms are noted for their spiny protective skin, their ―five-partǁ‖ body plan, and the presence of numerous
small appendages, the tube feet, which function as part of a water vascular system derived from the coelom.
The tube feet are used for locomotion, feeding, and respiration. The coelom carries out circulatory, respiratory,
and excretory functions. Water enters the vascular system through a madreporite on the aboral (upper) surface
of the animal.
Unlike arthropods, which have exoskeletons, echinoderms have internal skeletons. The skeleton is composed of
flattened calcareous plates called ossicles. Spines are outward extensions of the plates and are characteristic of
the echinoderms, often called the ―spiny-skinnedǁ‖ animals. In addition to spines, some echinoderms also have
pedicellaria extending from their surfaces. These are small pincers that aid in capturing food and keeping the
body surface clean.
The terms dorsal and ventral are not usually used to describe radially symmetrical organisms. Instead, the terms
oral (on the side of the mouth) and aboral (on the side opposite the mouth) are preferred. The mouth of most
radially symmetrical echinoderms is on the lower surface. Class Asteroidea (sea star or “star fish”) and Class
Echinoidea (sea urchins and sand dollars) and Class Holothuroidea (sea cucumbers) are represented in lab
today.
Terms to know and structures to identify: ossicles, dermal gills, pedicellariae, madreporite, ampullae, tube feet,
water vascular system
· Microscope Slides: Starfish tube feet (cs)
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· Prepared Specimens: Sea star, Echinaracnius sp. (sand dollar), Strongylocentrotus sp. (sea urchin), Sea
Cucumber, sea urchin internal skeleton
IX. Phylum Chordata – see Chapter 34, text
Background: All chordates share 4 common characteristics at some point in their life cycle: 1) a flexible but
incompressible supporting skeletal rod called the notochord, from which the name Chordata is derived; 2) a
dorsal hollow nerve cord lying above the notochord; 3) pharyngeal pouches, also called “gill pouches”,
located in the pharynx (anterior region of the gut); and 4) a post anal tail.
The phylum Chordata includes two subphyla, Urochordata and Cephalochordata, which do not have backbones.
These invertebrate chordates are also referred to as protochordates. A third subphylum, Vertebrata, contains
organisms that have a backbone, a bony spinal or vertebral column that replaces most of the notochord and
encases the nerve cord and a skull that encloses the anterior brain. There are seven living classes of
vertebrates that we will examine in this lab.
A) Subphylum Urochordata (sea squirts and tunicates)- see Fig. 34.5, text
Background: Tunicates or urochordates are a relatively diverse group of marine filter-feeders. They are solitary
or colonial and may be either attached to the substrate or free-floating. The most familiar forms are ascidians or
sea squirts. Adult sea squirts can be found attached to pilings or rocks in the intertidal zone of our coasts.
Larvae of solitary forms, however are free-swimming, bilaterally symmetrical “tadpoles” with the four
characteristic chordate features (notochord, pharyngeal gill slits, dorsal hollow nerve cord, and a post anal tail).
The larvae locate an appropriate substrate, attach with a sucker at their head end, and undergo a
metamorphosis during which most of the chordate characteristics are lost. Great interest has focused on this
larva because it is a typical chordate, whereas the adult sea squirts bear little resemblance to any other
representative of the phylum.
· Prepared Specimens: Halocynthia and Corella
B) Subphylum Cephalochordata (lancelets) – see Fig. 34.4, text
Background: Another small subphylum of chordates, the cephalochordates, contains small, bilaterally
symmetrical marine organisms with all characteristic features of chordates. However, unlike all other
representatives of the phylum, in cephalochordates the notochord extends all the way to the front of the head,
beyond the anterior end of the dorsal nerve cord. In other chordates, the notochord ends behind the expanded
part of the dorsal nerve cord or cerebral vesicle (behind the forebrain in vertebrates). Thus the name
cephalochordata (cephalo-, head) is appropriate for this group.
Terms to know and structures to identify: notochord, nerve cord, pharyngeal gill slits, post anal tail.
· Microscope Slides: Amphioxus (wm)
· Prepared Specimens: Amphioxus spp.
C) Subphylum Vertebrata – see pgs. 703 - 727, text
Background: The third subphylum of the Phylum Chordata contains organisms that have a backbone, a bony
spinal or vertebral column that replaces most of the notochord and encases the dorsal nerve cord, and a skull
surrounding the brain, an anterior expansion of the nerve cord. These organisms are called vertebrates. There
are seven vertebrate classes with living representatives.
Terms to know and structures to identify: notochord, dorsal nerve cord, pharyngeal gill pouches (slits), post
anal tail, vertebral column, endoskeleton, operculum
1. Aquatic Vertebrates (generally speaking):
According to the fossil record, the Superclass Agnatha or, “jawless fish”, are the oldest known fish. At one time,
they had bony skeletons, but the skeletons of modern representatives, the lampreys, (Class Petromyzontida),
are composed of cartilage. Lampreys feed upon their prey by attaching to the skin and sucking blood from soft
tissues—that is, the adult forms are parasites. The jawless fish have external gill slits.
Modern representatives of the Class Chondrichthyes include the rays and sharks. These cartilaginous fish, like
the Agnathans, have external gill slits. They also have no swim bladder.
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The Superclass Osteichthyes is made up of the “modern, bony” fish and is divided into 2 classes, Class
Actinopterygii (ray-finned fish) and Class Sarcopterygii (lobe-finned fish, e.g., coelacanth & lung fish). Most have
bony endoskeletons. This group includes many popular marine and freshwater fishes. The bony fish have gills
covered by a flap, or operculum. The skin of the bony fish is composed of scales.
· Prepared Specimens: Brook lamprey larva, Lamprey adult, Squalus (Dogfish pup), Perch, Hippocampus
2. “Transitional” Vertebrates (Class Amphibia)
Organisms of the Class Amphibia are incompletely adapted to terrestrial environments. Even in those species
that possess lungs, some gas exchange must occur through their skin. This requires that the skin be kept moist,
a condition that prevents the amphibians from living in a strictly terrestrial environment. Amphibians also depend
on water for reproduction. In many amphibians, such as the frog, eggs are laid in freshwater ponds or streams
and are fertilized externally. The tadpole larva is a swimming stage that undergoes metamorphosis into an adult
frog. Frogs may live on land, but most must return to the water to lay their eggs.
· Prepared Specimens and Skeletons: Rana pipiens, Frog tadpole, Salamander, Newt
3. Terrestrial Vertebrates (generally speaking): Reptilia, Aves, and Mammalia
Unlike amphibians, most reptiles (Class Reptilia) lead strictly terrestrial lives. There are two major adaptations
that allow this lifestyle. First, the skin of most reptiles is a tough, scaly skin that retards water loss and does not
need to be kept moist. Reptiles respire primarily through the respiratory membranes of the lungs as cutaneous
(skin) respiration is restricted by their tough skin. Second, reptilian eggs have hard or leathery shells reducing
water loss from the embryo to the environment. Although they are usually laid in moist environments, they do not
need to be laid in aquatic environments like amphibian eggs. The egg of the reptile contains all the food and
water needed for complete embryonic development.
Birds (Class Aves) trace their ancestry to groups within the Class Reptilia. The birds exhibit special
adaptations to allow flight for most organisms. In lecture (and in your textbook), we will discuss the potential
origins of flight, and the adaptations that led to this phenomenon. In short, the forelimb musculature of birds has
adapted to provide the lift necessary to attain and maintain flight. Birds also evolved feathery covering over most
of their skin, although the scaly feet generally lend a clue to their evolutionary origin (reptilian). Avian eggs
generally have even thicker shells than reptilian eggs allowing for them to be exposed to dry environments
without desiccation. In lab, you may examine homologous skeletal structures of avian skeletons and mammalian
skeletons, depending on time.
Class Mammalia also trace their ancestry to the Class Reptilia. Mammals have several adaptations that
distinguish them as a unique class of vertebrates. Females have mammary glands that produce milk to nourish
their young. Most young are incubated internally by the female, and born live. Mammals also have hair (fur) as
their external covering. Most mammals are homeothermic and endothermic maintaining a constant body
temperature largely through metabolic chemical reactions.
· Prepared Specimens and Skeletons: Various mammalian specimens
Lab Quiz Preparation: You should be able to identify organisms from the 9 phyla, or a subset of the 9 phyla,
viewed in lab today, and place them in a phylogenetic tree based on DNA evidence (Figure 32.11, Campbell
text). You should know the derived characters that define groups at branch points in the tree. Be familiar with the
main characteristics of each group, including body plan, tissue layers, type of body cavity (if any), as described
in the lab handout and the handouts provided in lab. You are responsible for identifying specific subphyla and
classes discussed in lab and lecture and knowing their characteristics, but you will not be asked to create
phylogenies for them during lab quiz.
Lab Notebook Check: Your lab notebook entry this week should contain a title and objective for this lab. You
should have sketches and notes from your observations each of the nine phyla you viewed in lab. For each
microscope slide, be sure and note the specimen and total magnification. Include descriptions and notes that will
help you with identification for study for the practicum!