Download The Animal Kingdom and Sponges Laboratory

The Animal Kingdom and Sponges
Laboratory
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Station 1
Introduction to the Kingdom Animalia
There are well over 1 million extant species of animals. Many of these forms are very
familiar to us like birds, earthworms, or snails. Others may not be as easily recognized as
animals at first glance, like a colorful sponge or a slow-growing staghorn coral.
Members of the animal kingdom are:
• eukaryotic
• heterotrophic by ingestion
• multicellular
• composed of cells not surrounded by a cell wall and rely on structural
proteins (like collagen) for support
• composed of specialized tissues (exception : sponges) which arise from
embryonic germ layers
• typically motile; not sessile like plants
• diploid and reproduce sexually
Most zoologists agree that the ancestors to animals were colonial choanoflagellates
(cells with a flagellum surrounded by a collar) and that the first animals lived some 700
million years ago.
Animals may be classified based on grades of body plans; a set of morphological or
developmental characteristics. The processes of evolution have altered the generalized
body plans to allow each particular animal to be successful in its environment.
During the next few lab exercises, you will be closely examining various animal forms.
Therefore, it will be important that you understand how to describe the locations of
various animal body parts. Listed on page 2 are anatomical terms that you should become
familiar with to fully understand animal anatomy.
In this exercise, we will use the human skeleton and the bone position to illustrate the
anatomical terms. Using the human skeleton and laminated sheets locate and label each
of the human bones.
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Anatomical terms
Dorsal - near or towards the back
Ventral - near or towards the belly
Lateral - near or towards the sides; right and left
Median – near or towards the middle
Anterior – near or towards the front end
Posterior – near or towards the hind end
Caudal – refers to the tail
Cranial – refers to the head
Longitudinal – parallel to the long axis from head to tail
Transverse – perpendicular to the long axis from head to tail
Superficial – near the surface
Deep – below the surface; under
Pectoral – relates to the chest
Pelvic – relates to the hips region
Proximal – directional term; close to main part of the body
Distal – directional term; far from the main part of the body
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Review Questions
* Be sure you can identify the bones before next weeks’ quiz.
1. Name a bone which is transversely oriented.
2. Name the bones which form the dorsal, medial, longitudinal axis of the skeleton.
3. Name a bone which is medially located in the pectoral region.
4. Name the bones distal to the carpals.
5. Name a bone located proximally to the elbow joint.
6. Name the bone which articulates laterally with the clavicle and scapula.
7. Name the bone which articulates laterally with the pelvic girdle.
8. In the space below, list the bones of the upper limb in order beginning with the most
proximal bone first.
9. Humans have a set of three fused caudal vertebrae – these vertebrae are commonly
known as the ______________.
10. List in the space below the characteristics of members of the Kingdom Animalia.
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Station 2
Animal Phylogeny
In this exercise, we will examine the different morphological features commonly used to
classify animals.
Tissues
By definition, most animals have a body composed of tissues. However, the sponges
(Phylum Porifera) are an exception as they lack such tissues and are known as
parazoans. Animals classified as eumetazoans develop from an embryo that develops
through a process known as gastrulation. During gastrulation, the embryo develops
distinct tissue layers (called germ layers). These germ layers (endoderm, ectoderm or
mesoderm) will give rise to the more complex tissues and organs as the animal develops.
Endoderm tissue forms the lining of the digestive tube; ectoderm tissue forms the outer
covering of the animal and in some cases, the central nervous system. Mesoderm tissue
may produce muscle and the remaining tissues and organs. Some eumetazoans are
diploblastic and only develop endoderm and ectoderm (i.e. Hydra). Others are
triploblastic possessing a mesoderm layer between the ectoderm and endoderm
(i.e. earthworms and frogs).
Symmetry
Animals are also classified based on symmetry. Parazoan sponges lack symmetry and
are known as asymmetrical. Eumetazoans may exhibit radial symmetry or bilateral
symmetry. Radial symmetry produces only dorsal and ventral sides; no anterior or
posterior; no lateral sides. Bilateral symmetry produces right and left lateral sides as
well as dorsal and ventral sides. Many animals that exhibit bilateral symmetry also have
an anterior and posterior orientation. Sensory structures are normally positioned
anteriorly forming the head (the development of a head is an evolutionary trend known as
cephalization). Most diploblastic animals are radially symmetrical while triploblastic
animals are bilaterally symmetrical.
Label the figures above- radial symmetry, bilateral symmetry, dorsal,
ventral, anterior, posterior
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Body Cavities
Triploblastic animals may be further broken into three distinct groupings based upon the
presence or absence of a body cavity.
Acoelomate animals (i.e. planarian) do not have a body cavity positioned between their
digestive cavity and the outer body wall. Their bodies are a solid mass of tissue.
Pseudocoelomate (pseudo = false) animals (i.e. a roundworm) have a hollow cavity
located deep to their outer body wall. This cavity is filled with fluid and surrounds the
digestive tract. It is known as a false cavity (pseudocoelom) because mesoderm tissue
only surrounds the cavity on one side; the endoderm tissue forms the other cavity
boundary.
Coelomate animals (i.e. earthworms and frogs) have a hollow cavity which is completely
lined with mesodermally-derived tissues. There are advantages to having a coelomic
cavity. For example, muscle (derived from mesoderm) may move food through the
digestive system independently from the movements of the outer body. Coelomates may
be categorized as protostomesor deuterostomes based upon embryonic development
events. For example, in protostomes, the blastopore becomes the anterior opening of the
digestive tract (mouth). In deuterostomes, the blastopore becomes the anus, while the
mouth forms secondarily.
Label the figures above – ectoderm, endoderm, mesoderm, acoelomate, pseudocoelomate, coelomate
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While zoologists currently recognize about 36 animal phyla, the relationships among
these groups is under constant debate and changes frequently. Over 90% of animal life is
contained within nine major animal phyla; it is these phyla on which future labs will
concentrate.
Examine the specimens representing the nine phyla and compare to the chart outlining
the common names and general body plans. Use this information to complete the
phylogenetic tree below by placing the correct phyla name in the boxes.
molts
segmented
Blastopore Æ mouth
segmented
Blastopore Æ anus
False body cavity
No body cavity
Radial symmetry
No tissues
Coelomic cavity
Bilateral symmetry
Tissues present
Review Questions
Animals
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1. List the three germ layers that develop in a bilaterally symmetrical animal.
2. Fill in the chart below by listing the type of symmetry observed in each specimen:
Animal
Type of symmetry
Sponge
Flatworm
Insect
Jellyfish
Human
3. Name a triploblastic organism you examined today.
4. Name a diploblastic organism you examined today.
5. Define cephalization.
6. What is the difference between a pseudocoelomic cavity and a coelomic cavity?
7. Fill in the chart below by listing at least one representative organism for each of the
nine phyla.
Phylum name
Examples
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Station 3
The Phylum Porifera – The sponges
Sponges are parazoans that live in marine or aquatic habitats. They are the simplest
animals as their body does not consist of true tissues but rather a loose colony of
organized cells. Typically, a sponge consists of amoebocytes, choanocytes, porocytes
and epidermal cells with each cell having a particular function. The amoebocytes may
digest food and distribute the food to other cells, as they are capable of locomotion
throughout the sponge’s body. The epidermal cells form the outer protective surface of
the sponge and surround the porocytes, which form the openings into the sponge’s body.
As sessile organisms, sponges grow attached to rocks, coral, shells, or other large
submerged objects relying upon their food coming to them. Sponges obtain nutrients by
filtering the water column using flagellated collar cells (choanocytes) to assist with the
movement of water through their porous bodies. As the flagella move, water is drawn
through the porocytes and suspended nutrients are collected in the collars and
phagocytized.
Spicules or a framework of a fibrous protein called spongin forms the extracellular matrix
and determines a sponge’s shape. Spongin in bath sponges makes them useful in
cleaning things and for absorbing water.
Use the drawing below to label choanocyte, spicule, amoebocyte, porocyte, epidermal
cell, extracellular matrix
Sponge anatomy
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Examine the various sponge specimens and compare them to the photos below.
Bath and finger sponges are composed of lots of extracellular spongin. They do possess
spicules that may vary greatly in shape. The glass sponges contain six-rayed spicules
made of silica, which gives them a coarse texture. Calcareous sponges, like the tiny
Grantia, are composed of calcium carbonate spicule, which gives them a chalky
appearance.
Grantia
Finger sponge
Glass sponge
Bath sponge
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Review Questions
1. Compare the texture of a bath sponge to a glass sponge.
2. Define sessile.
3. How do sponges obtain nutrients?
4. What type of spicules are found in a glass sponge?
5. What is the composition of Grantia’s spicules ?
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