Metazoans, Animal Tissues & Sponges: Phylum Porifera
4.1
Lab #4 - Biological Sciences 102 – Animal Biology
This lab is designed to introduce you to multicellular animals and their basic tissue structure with
particular reference to the simplest of the metazoans–the sponges of the Phylum Porifera.
Metazoans
The diversity seen among the unicellular protozoa is a product of their various subcellular structures
and organelles. In contrast, the complexity of metazoans or multicellular animals is due to the
evolution of cells working together to form larger units each dedicated to a specific function necessary
for the survival of the entire animal. Metazoan cells cannot survive on their own outside of the whole
organism (except in cell culture with lots of feeding and maintenance by biologists). The simplest
metazoans such as the sponges are collections of cells that show some division of labor, but less
distinction in the tasks of specific cells seen in more complex metazoans. Animals that have true
tissues possess cells that work together as a highly coordinated unit. In most animals, these tissues
are further organized into organs. Metazoans are part of the opisthokont lineage (the eukaryotic
clade that has a single posterior flagellum, if a flagellum is present) along with the fungi,
choanoflagellates and microsporidians. Microsporidians are protozoan parasites living inside the
cells of many animals including humans. Choanoflagellates are solitary and colonial protozoans in
which each cell has a flagellum surrounded by a collar of microvilli.
Choanoflagellates closely resemble the feeding cells (choanocytes) seen in sponges. Sponges are
basically aggregations of cells held together by an extracellular matrix. Biologists are currently
studying the cell-to-cell interactions and signaling mechanisms that lead to colony formation in
choanoflagellates in order to better understand the evolution of the first simple multicellular animals.
See and study the textbook regarding the syncytical ciliate hypothesis and the colonial
flagellate hypothesis (look them up in the textbook index).
Phylum Porifera: The Sponges
While lacking true tissues, sponges have a cellular level of organization. There is division of labor
among their cells, but there are no organs, no systems, no mouth or digestive tract, and only the hints
of nervous integration. There are no germ layers (ectoderm, mesoderm or endoderm). Adult sponges
are all sessile in form. Some have no regular form or symmetry; others have a characteristic shape
and radial symmetry. Sponges may be either solitary or colonial. See lab exercise #7 on sponges in
the Hickman lab manual for diagrams and photos.
Important characteristics of sponges are:
 Sponges do not possess true tissue organization
 possess pores and canal systems
 flagellated sponge feeding cells, called choanocytes, which line their cavities and create
currents of water
 internal skeletons of spicules and/or protein fibers (spongin).
 internal cavity (spongocoel) that opens to the outside by an osculum.
 most sponges are marine, though there are a few freshwater species; freshwater forms
are found in small, slimy masses attached to sticks, leaves, or other objects in quiet ponds and
streams
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Classification of the Phylum Porifera
Class Calcarea Cal-ca're-a (Gr. calc, limy). About 700 species; sponges with spicules of calcium
carbonate, needle-shaped or three-rayed or four-rayed; canal systems asconoid, syconoid, or
leuconoid; all marine. Examples: Sycon, Leucosolenia
Class Hexactinellida (hex-ak-tin-el'i-da) (Gr. hex) six, + aktis, ray). About 500 species; sponges with
three-dimensional, six-rayed siliceous spicules; spicules often united to form network; body often
cylindrical or funnel-shaped; canal systems syconoid or leuconoid; all marine, mostly deep water.
Examples: Euplectella (Venus' flower basket), Hyalonema
Class Demospongiae (de-mo-spun'je-e) (Gr. demos, people, + spongos, sponge). About 7000 species;
sponges with siliceous spicules (not six-rayed), spongin, or both; canal systems leuconoid; one family
freshwater, all others marine. Most sponges belong to this class.
Examples: Spongilla (freshwater sponge), Spongia, (commercial bath sponge), Cliona (a boring sponge)
Your instructor will review the basic structure of sponges including asconoid, syconoid and
leuconoid canal systems, cell types found in sponges such as choanocytes, their skeletons and basic
reproduction.
Class Calcarea
Class Demospongiae
Class Hexactinellida
Types of Animal Tissues & Histology (the study of tissues)
See lab exercise #4 on animal tissues in the Hickman lab manual for diagrams of tissues.
As we proceed through the various animal phyla, we will be discussing most of these tissues in lab
and lecture. You are not responsible for knowing all of this material now, but you must know the four
basic types of tissues, their basic characteristics and an example of each. You will want to use these
pages as reference material during the course.
There are four basic types of tissues that are recognized in animals. Some animals show less
distinction between the four separate types.
 connective tissue
 epithelial tissue
 muscular tissue
 nervous tissue
CONNECTIVE TISSUES
In general, connective tissue is quite diverse and is not as cellular as other types of tissue.
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
All connective tissues arise from the mesoderm layer (mesenchyme) of the developing embryo.
Connective tissue provides a stiffness to the animal body (bone) and helps the body withstand tension,
stress and shearing (twisting) forces.
Basically, connective tissue is composed of:
1. An intercellular matrix (in the intercellular space between connective tissue cells)
This matrix can be fluid as in blood or it can be more solid as in bone.
The matrix is a mixture of proteins that are secreted by the cells in the connective
The proteins in the matrix are usually fibrous (long strands).
tissue.
2. Connective tissue cells
These cells secrete the intercellular matrix and can have a variety of functions.
For instance, the red blood cells (erythrocytes) & white blood cells (leukocytes) in blood, the
osteocytes of bone, or the adipocytes in fat tissue.
Often some of these cells make new connective tissue (blast cells) while other cells degrade the
connective tissue (clast cells).
CONNECTIVE TISSUE EXAMPLES:
Dense Connective Tissue: function = tightly packed fibers that are aligned with the forces applied to
the tissue; makes this a strong, somewhat flexible tissue found in tendons, aponeuroses, elastic
tissues and ligaments
Tendons = cords of dense regular connective tissue that attach skeletal muscles to bones
Aponeuroses = collagenous sheets or ribbons that resemble flat tendons; these often cover the surface
of some muscles
Elastic tissue = tolerates expansion and contraction; found in the walls of blood vessels and
respiratory passageways; often underlies transitional epithelia
Ligaments = resemble tendons, but they connect bone to bone; ligaments have significant amounts of
elastic as well as collagenous fibers
TYPES AND CHARACTERISTICS OF CONNECTIVE TISSUE
There are two different types of Dense Connective Tissue:
1. Dense Regular Connective Tissue = has the collagen fibers aligned tightly in a parallel fashion
There is a grain or orientation to dense regular connective tissue (such as tendon)
2. Dense Irregular Connective Tissue = has the collagen fibers that run in many directions and
there is no particular orientation to the fibers which makes this tissue strong in several directions
(such as skin)
Structure
Mostly collagenous fibers (collagen) bundled like fibers in a rope = strength
Histology = mostly fibers, may be “wavy” in appearance (regular) or “cracked”
in appearance (irregular)
Cells = fibroblasts which secrete the fibers and become fibrocytes
Fibers = collagen fibers
Loose (Areolar) Connective Tissue: function = wraps organs, occurs between some muscles in
sheets, occurs at the boundaries of tissues such as between fat and muscle
Histology = large, pink stained collagen fibers; smaller & darker elastic fibers and a collection
of cells in a relatively random collection; looks like handfuls of straw that have been thrown
into the air and allowed to fall in a random arrangement; loosely packed
Cells = fibroblasts, fibrocytes, mast cells, macrophages (the last 2 are types of immune cells)
Fibers = large collagen fibers with smaller elastin fibers
Elastic Connective Tissue: function = occurs in the walls of arteries
Histology = looks like dark squiqqly lines in the walls of arteries
Cells = fibroblasts & fibrocytes
Fibers = elastic fibers made of the protein elastin
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Lab #4 - Biological Sciences 102 – Animal Biology
Reticular Connective Tissue: function = found in internal organs such as the liver, spleen and lymph
nodes; reticular connective tissue provides an internal framework for the organ
Histology = if the slide is stained with silver, the reticular fibers will appear black, if the slide
is stained with Masson stain, the reticular fibers will appear blue; look for branched fibers
among small round cells
Cells = fibroblasts & fibrocytes
Fibers = reticular fibers
Adipose Tissue (fat): function = very cellular; store large amounts of lipids (fats); the nucleus of the
cell and the cytoplasm remain on the outer part of the cell near the cell membrane
Histology = in prepared slides, the fat has typically been dissolved during preparation. You
should see large, empty cells with some cell nuclei near the edge of some cells; may look like a
honeycomb
Cells = adipocytes (fat cells)
Fibers = few fibers if any at all
Osseous Tissue (vertebrate bone): function = support, rigidity, protection, attachment point of
muscles for movement, cavity for the formation of blood cells (erythrocytes & leukocytes). The
exoskeleton of arthropods is comprised of proteins and the polysaccharide chitin.
Structure
In vertebrates, the matrix of bone consists of:
about 30% collagen (protein) = flexibility and tensile strength
about 70% calcium and phosphate crystallized into bone salts = hydroxyapatite = makes bone
rigid
Osteocytes produce the cartilaginous matrix of bone, bone is a physiologically active, living
tissue with its own blood supply that allows bones to heal relatively quickly; bone is constantly
reworked and reformed according to your body’s needs
Histology = dense bone looks like tree rings while trabecular (spongy) bone looks like
scaffolding with spaces in it
Cells = osteocytes = cells found in mature bone that arose from osteoblast cells
osteoblasts = bone forming cells that produce new bone tissue
osteoclasts = bone degrading cells (“bone eating” cells); large, multi-nucleate cells that
make the medullary cavity (hollow inside of long bones) and degrade bone to release
calcium and/or phosphate as needed
Fibers = collagen fibers
Microscopic View
of Vertebrate Bone
- Osseous Tissue
formed of Osteons -
Cartilage (and Perichondrium) = a
relatively simple, structural connective
that is nonvascular (without a direct blood
supply) and grows relatively slowly
tissue
Structure
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Consists primarily of intercellular matrix with cells chondrocytes (chondro = from the Greek
for grain = cartilage) interspersed in the matrix within small pockets called lacunae. Cartilage
is a pliable material that allows for movement. The intercellular matrix is made up of protein
and carbohydrate that forms a gel in which fibers and cells are found. The perichondrium is
dense irregular connective tissue that is found on the surface of cartilage. Blood vessels run
through the perichondrium and nutrients diffuse into the chondrocytes, so if cartilage
becomes damaged, it heals slowly as there is no direct blood supply to each chondrocyte.
There are three types of cartilage in the human body as described below.
Function of cartilage
Cartilage in the joints provides a smooth surface through the full range of movement during
which it is continuously subjected to severe stresses such as the pull of gravity in weight
bearing joints and muscle tension in all joints
Hyaline Cartilage:
Function = most common type in the body; found at the apex of the nose, the ends of many
long bones within joints, between the ribs and sternum, the larynx
Structure
Glassy and clear in appearance in fresh tissue; hyaline cartilage is like crunchy gristle
Histology = often appears clearish with a pinkish tint in prepared slides; fibers are not obvious
as they blend into the matrix; chondrocytes are often found in pairs; relatively large lacunae
Cells = chondrocytes are the cells that secrete the proteins that make up cartilage
Fibers = collagenous fibers (fibers made of collagen). Chondrin is a major protein component
of collagen
Elastic Cartilage:
Function = flexible with resilience, it can be flexed but it will “bounce back”; forms the pinna of
the ear (earlobe), epiglottis, parts of the nose
Structure
Made from chondrocytes with proportionally less chondrin protein than hyaline cartilage;
contains a lot of the protein elastin that is a coiled protein at the molecular level. Elastin has
fibers that run in random directions to help provide elasticity.
Histology = if stained with silver then the elastic fibers appear black
Cells = chondrocytes
Fibers = mainly elastin fibers
Fibrocartilage:
Function = similar to hyaline cartilage with more collagenous fibers (collagen); fibrocartilage
can withstand much tension, but it still has some flexibility; located in areas with greater
stress such as the intervertebral disks, pubic symphysis, and the menisci of each knee
Structure
lots of collagen; collagen can be bent, but it resists stretching (as the fibers tend to run parallel
and are densely interwoven = durable and tough)
Histology = collagen fibers are relatively easy to see; chondrocytes are often found in rows of
four or five; lacunae are less obvious
Cells = chondrocytes
Fibers = mainly collagen fibers
Blood (vertebrates)/Endolymph (many invertebrates) = is
composed of four major portions:
erythrocytes, leukocytes, thrombocytes (platelets) and plasma (noncellular fluid portion of blood); blood will be covered in much
greater detail in later lectures
Structure
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Matrix is fluid (mostly water) with no fibers present
Cells = erythrocytes (red blood cells) & leukocytes (white blood cells)
Histology = pink discs = RBCs; darker purple = nuclei of leukocytes
Erythrocytes (Red Blood Cells)
of various vertebrate classes
Note that mammals have red blood cells which lack a cell nucleus while all other
vertebrates (fish, amphibians, reptiles and birds) have erythrocytes that possess a cell
nucleus
EPITHELIAL TISSUE
Epithelial tissue is highly cellular tissue that forms coverings and linings of an animal’s body.
Epithelial tissue attaches to underlying layers by way of a basement membrane that is a non-cellular
adhesive layer. For instance, in the skin, the epidermis is made of epithelial tissue that is attached to
the underlying dermis by a basement membrane. The basement membrane consists of glycoproteins
and both fine and coarse protein filament which are produced by connective tissue cells. Epithelial
tissue is classified according to the shape of the cells and the number of cell layers present.
Epithelial cell shapes = squamous (flattened), cuboidal, or columnar
Simple epithelium is only one cell layer thick
Stratified epithelium is more than one cell layer thick
Simple Squamous Epithelium
Location in the animal body: air sacs of the lungs, lining of blood vessels, many body membranes,
part of the kidney tubules and nephridia
Structure: one layer of flat cells that lie on the basement membrane
Function: provides a smooth, slippery surface to reduce friction and allows for diffusion of substances
during absorption or secretion
Simple Cuboidal Epithelium
Location in the animal body: forms many of the major glands and ducts, lines tubules (such as
sweat ducts) and tubules of the kidney and nephridia
Structure: one layer of tube-like or pie-like shaped cells (sort of like squashed cubes) that are fairly
uniform in diameter attached to the basement membrane; often involved in the secretion of fluids
(sweat, oil) or in filtration (as in the kidney)
Simple Columnar Epithelium
Location in the animal body: ciliated type lines the oviducts; non-ciliated type lines the digestive
tract
Structure: one layer of tall column-like cells attached to the basement membrane; the cells may
be ciliated or non-ciliated
Function: assists in the movement of substances through tubes in the body and plays vital roles in
the process of absorption in the intestines; protection, absorption, and secretion
cilium (= singular; cilia is plural) = a slender organelle that extends above the free surface of an
epithelial cell, and usually undergoes coordinated cycles of movement. Cilia possess the same 9 +
2 arrangement of microtubules seen in flagella, but cilia are shorter and more numerous.
Cilia are not a type of tissue, but a cell organelle seen in the cells of some tissues.
Pseudostratified Ciliated Columnar Epithelium
Location in the animal body: lines portions of the respiratory tract and the male reproductive tract
Structure: one layer of ciliated columnar cells attached to the basement membrane, although it
may look like it is formed from multiple cell layers
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Function: produces a mucus and traps small particles which are carried out of the lungs via
coordinated movements of the cilia
Stratified Squamous Epithelium
Location in the animal body: surface of the skin, lines the female reproductive system, mouth,
throat and anus
Structure: multiple layers of flat cells attached to the basement membrane; may have cuboidal
cells at the basement layer, but the cells along the free edge are flattened; these flattened cells may be
keratinized or non-keratinized; keratin is a tough protein that hardens cells in the outer layers of the
skin, hair and nails
Function: multiple cell layers protect underlying layers from abrasive, pathogenic, or chemical
damage
Stratified Cuboidal Epithelium (multiple layers of cuboidal cells) is relatively rare, but provides for
some protection, secretion and absorption in some ducts (e.g. sweat gland ducts)
Stratified Columnar Epithelium (multiple layers of columnar cells) is relatively rare, but provides
for some protection in salivary gland ducts, the epiglottis, mammary ducts and the urethra
Transitional Epithelium
Location in the animal body: lines the renal pelvis, urinary bladder and ureters in vertebrates
Structure: multiple layers of irregularly shaped cells lie on top of the bladder, but the cells along
the free edge are not flattened (as in stratified squamous epithelium); when the bladder fills, the cells
along the free edge flatten out
Function: the cell structure and multiple layers have an unusual amount of stretching capacity that
allow for significant changes in the volume of portions of the urinary tract
MUSCLE TISSUE
Muscle tissue is a highly cellular tissue characterized by
its ability to contract in response to an appropriate
excitatory stimulus.
Muscle fibers are individual muscle cells, each of which
is contractile and can shorten in length due to the
sliding of protein filaments (actin, myosin & other
proteins) along one another within the cell.
Skeletal Muscle Fibers
Note that skeletal muscle fibers are striated (“striped”)
and multinucleate (there are multiple cell nuclei per cell membrane)
Three Types of Muscle Tissue = Skeletal, Cardiac, and Smooth
Skeletal Muscle (striated, voluntary, multinucleate)
Location in the animal body: all the muscles which are used voluntarily to control movement; this
is the type of muscle that moves bones (in both arthropods and vertebrates) and is found near all the
joints of the skeletal system
Structure: striated due to the organization of the protein filaments in the muscle fibers; skeletal
muscle cells form a syncitium, that is, they are multinucleate (more than one nucleus within a single
cell membrane)
Function: modulate all voluntary muscle action & movement
Cardiac Muscle (striated, involuntary, uninucleate)
Location in the animal body: only found in the heart and heart-like structures; makes up most of
the heart; involuntary
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Structure: striated, but the striations are less regular and obvious as compared to skeletal muscle;
cardiac muscle cells are usually uninucleate (one nucleus per cell); individual cells are connected to
each other by intercalated discs that hold the cells together and allow for electrical communication
between certain cells of the heart
Function: provides for the involuntary pumping of blood by the heart
Smooth Muscle (nonstriated, involuntary, uninucleate)
Location in the animal body: found in the digestive tract, reproductive tracts and other internal
organ systems; involuntary
Structure: nonstriated, spindle-shaped uninucleate cells with a centrally located fusiform shaped
cell nucleus when the cells are relaxed; when the cells are contracted, the cell nucleus has a corkscrew shape
Function: provides for the involuntary movement (peristalsis) of food products through the digestive
tract, the movement of sperm and egg in the female reproductive tract, the movement of excretory
products, the activation of pili muscles in the skin, movements of sensory organs, the contractions of
the uterus at parturition (labor), etc
NERVOUS TISSUE
Nervous tissue is a highly cellular tissue characterized by an ability to conduct electrochemical
signals. The individual cells are termed neurons. Each neuron is composed of dendrites (which
receive the incoming signal), a cell body (or soma where the cell nucleus is found), an axon (a long
cytoplasmic extension, “like a wire”), and a terminal (or synaptic knob) near the synapse where one
neuron conveys the impulse to another neuron. There are many different shapes of neurons found in
the animal kingdom.
Location in the body: the nervous system or nerve net of an animal
Structure: composed of neurons and also contains special support and nursing cells called glial cells
(or neuroglia) or similar cell types.
Function: conduct electrochemical impulses that allow the nerve net, cerebral ganglia or brain and
spinal cord to communicate with other parts of the animal’s body
A typical multipolar nerve cell (neuron)
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
LAB PROCEDURE
NAME:
LAB SCORE:
Organization of a Syconoid Sponge

Using your textbook and/or the Internet, label the diagram below with the following terms:





osculum (surrounded by long protruding spicules)
flagellated canal (radial canal)
incurrent canal
spongocoel
ostium

With a colored pen or pencil, indicate (with arrows) the path of water flowing into and out of the
sponge.
Grantia sp. as seen under a dissecting scope

Examine a prepared slide of a Grantia sp. cross-section under the compound scope and compare
it to the diagram below. Be sure you can identify the basic parts indicated on page 4.10.
Metazoans, Animal Tissues & Sponges: Phylum Porifera
Lab #4 - Biological Sciences 102 – Animal Biology

What are the evolutionary and functional advantages of being multicellular?
4.10
Metazoans, Animal Tissues & Sponges: Phylum Porifera
4.11
Lab #4 - Biological Sciences 102 – Animal Biology






Using your textbook and/or the Internet, label the diagram below with the following terms:
ostium
flagellated canal (radial canal)
prosopyle
apopyle
mesohyl (mesenchyme)
Sponge Skeletons: Spicules




incurrent canal
amoebocyte
choanocyte
spicule
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Various Types of
Sponge Spicules
Note that spicules can have one,
two, three, four, five, six rays or
more
Spicules can be made of protein,
calcium carbonate or silica

Prepare and examine some Grantia sp. spicules by doing the following:
1.
2.
3.
4.
5.
Place a small piece of the sponge in a depression slide and add a drop or two of bleach.
Wait about five minutes for the bleach to take effect.
Add a cover slip.
Observe them under the compound scope.
Note that there are no common intact sponge spicule types that exhibit square ends. If features
such as these are observed, they represent fragments of damaged spicules and should not be
sketched. Look around for undamaged spicules.
6. In the space below, draw a few representative examples of the types of spicules you
observe. Note how many rays (points) are found on each spicule.
7. After you have drawn the spicules, add a drop or two of acid (HCl) to the spicules.


Do these spicules dissolve in acid?

To which Class of sponges does Grantia sp. belong?
Draw a sketch of the Grantia sponge spicules below.
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology

Prepare and examine some spicules from the local sponge, Tethya aurantia. by removing a
small fragment from the cortex of the sponge and following the same procedure as above.
1. In the space below, draw a few representative examples of the types of spicules you observe
from Tethya aurantia. Note how many rays (points) are found on each spicule?
2. After you have drawn the spicules, add a drop or two of acid (HCl) to the spicules.


Do these spicules dissolve in acid?

What compound are these spicules made of?
Draw a sketch of the Tethya sponge spicules below.
The axial filament of the strongyle megasclere spicules is a protein fiber. This fiber is the substrate
on to which silica is deposited during spicule biosynthesis. Sponges of the Class Calcarea lack this
organic core within their spicules as control of calcification is mediated by proteins occluded within
the various CaC03 phases (amorphous or crystalline).
Live Sponge Specimens



Carefully observe all of the live sponge specimens displayed in the lab noting the similarities and
differences in their basic body plans, color, etc.
Fill in the table below with the requested information for any of the live sponge species.
The canal system may not be obvious by visual inspection of the sponge alone. Often canal
systems must be determined by microscopic examination. You should refer to the Internet
for sources to determine the type of canal system for each species.
Genus
1.
2.
3.
4.
5.
species
Class
Type of
canal system
Metazoans, Animal Tissues & Sponges: Phylum Porifera
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Lab #4 - Biological Sciences 102 – Animal Biology
Classification of an Unknown Sponge
Working with your instructor, attempt to key out and identify at least the class of the unknown sponge
displayed in the lab. Note that the following characteristics will be useful in determining the
classification of the unknown sponge:

General shape of specimen

Size, quantity and location of the ostia (these may be difficult to see without a dissecting
scope)

Size, quantity and location of the oscula (these may be difficult to see without a dissecting
scope)

General dimensions of the specimen

Color of the specimen

Type of spicules – calcium, silica, and/or protein based

Number of spicule rays

Class of the unknown sponge:

Genus and species of the unknown sponge:
Important Terms Related to Animal Tissues
homeostasis = relative to an animal’s physiology, the maintenance of the relatively stable internal
environment that is necessary for the animal to survive in a changing external environment.
Homeostasis is a state of equilibrium characterized by a dynamic interplay between outside forces that
tend to change an organism's internal environment and the internal control mechanisms that oppose
such changes. Homeostasis is essential for the survival of each cell, and each cell, through its
specialized activities, contributes as part of a body system to the maintenance of the internal
environment shared by all cells
tissue = a cooperative unit of many similar cells that perform a specific function
organ = a structure consisting of at least two of the basic tissue types adapted as a group to perform a
specific function.
organ system = a collection of organs the work together as a unit for a specific function necessary to
maintain homeostasis for an animal (eg. the circulatory system, the digestive system, the respiratory
system, etc.)
parenchyma = the chief functional cells that comprise an organ (eg. cardiac muscle cells in a heart)
stroma = supportive tissues in an organ (eg. the pericardial sac made of connective tissue that
surrounds and lubricates the beating heart)
LABORATORY NOTES:
Metazoans, Animal Tissues & Sponges: Phylum Porifera
Lab #4 - Biological Sciences 102 – Animal Biology
LABORATORY NOTES:
4.15