Name ______________________________ Class___________________Date__________________
Invertebrate Diversity
Study Guide A
Answer Key
7. Choanocytes
SECTION 1. ANIMAL
8. Amoebocytes
CHARACTERISTICS
9. a and c; Sketches will vary.
1. size or shape; ecosystems; move
10. b and d; Sketches will vary.
2. heterotrophs
11. polyp stage
3. collagen
12. nerve cells
4. sexually
13. mesoglea
5. Most
14. contracting cells
6. lack; have; collagen
15. cnidocytes
7. embryos
16. nematocyst
8. protein
17. digestion
9. nucleotides
10. Poster designs will vary. Share some with SECTION 4. FLATWORMS,
the class. MOLLUSKS, AND ANNELIDS
1. phylum
SECTION 2. ANIMAL DIVERSITY
2. classes
1. backbone; five
3. solid; gut
2. backbones; ninety-five
4. diffusion; closer to
3. structural; functional
5. humans; water
4. homeobox
6. egg; flea; egg; larva; flea; flea; larva;
5. embryonic
adult; host
6. greater
7. opposite ends
7. oxygen
8. a, b, and d
8. one; two; sketches will vary
9. feeding/eating
9. circle; sketches will vary
10. organs
10. mouth;
11. gills
11. anus
12. mollusk; Blood
12. separations in the mesoderm
13. annelids
13. spiral cleavage.
14. move
14. anus
15. mouth SECTION 5. ROUNDWORMS
16. pouches created by folds in the gut tube 1. nematodes; numbers; diversity
17. radial cleavage. 2. protostomes; bilateral
18. structural; functional 3. exoskeleton; cuticle
19. first; second 4. chitin; shed
5. blunt; tapered; chitin; pseudocoelom; have;
SECTION 3. SPONGES AND
do not have
CNIDARIANS
6. e; d
1. muscle; nerve; sessile
7. e; a
2. hard; toxic; growing; predators; parasites
8. c; b
3. Sexual: b; c; f; g. Asexual: a; e; d
9. not completely
4. body wall
10. Poster designs will vary. Share some with
5. spongin; spicules
the class.
6. Pinacocytes
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Holt McDougal Biology i Invertebrate Diversity
Study Guide A
Name ______________________________ Class___________________Date__________________
Study Guide A continued
SECTION 6. ECHINODERMS 7. d; g
1. internal; ossicles 8. e; h
2. catch connective 9. c; j
3. flexible; stiff 10. a; f
4. water; arm; ring canal 11. b; i
5. circulatory; movement 12. skeleton
6. a, anus; b, tube feet; c, stomach; d, mouth. 13. Brochure designs will vary. Share some
Correct order = b, c, d, a with the class.
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Holt McDougal Biology ii Invertebrate Diversity
Study Guide A
Name ______________________________ Class___________________Date__________________
Section 1: Animal Characteristics
Study Guide A
KEY CONCEPT
Animals are diverse but share common characteristics.
VOCABULARY
collagen homeotic homeobox
MAIN IDEA: Animals are the most physically diverse kingdom of organisms.
Fill in the blank with the word or phrase that best completes the sentence.
1. Animals are a remarkably diverse group of organisms. For example:
Animals have different diets.
Animals range greatly in _____________.
Animals live in a variety of different _____________.
Animals have different ways to _____________ from one place to another.
MAIN IDEA: All animals share a set of characteristics.
Circle the word or phrase that best completes the statements about the common
characteristics shared by all animals.
2. All animals are multicellular 3. Animal cells are supported by cell
autotrophs / heterotrophs. walls / collagen.
Animal characteristics
4. Animals are diploid and most 5. All / Most animals have Hox
reproduce sexually / asexually. genes.
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Holt McDougal Biology 1 Invertebrate Diversity
Study Guide A Section 1: Animal Characteristics
Name ______________________________ Class___________________Date__________________
Study Guide A continued
Circle the word or phrase that best completes the statement.
6. Animal and plant cells differ, because animal cells have / lack rigid cell walls,
while plant cells have / lack rigid cell walls. Animal cells use an extracellular
network of collagen / phloem for support.
7. Hox genes influence animal development by defining the head-to-tail pattern
of development in animal gametes / embryos.
Vocabulary Check
Fill in the blank with the word or phrase that best completes the sentence.
8. Collagen is a three-stranded ______________ unique to animals.
9. Homeotic genes are a class of genes that control early development in animals.
Every homeotic gene has a specific sequence of 180 ______________ called
homeobox (Hox) genes. The homeobox genes define the head-to-tail pattern of
development in animal embryos.
Be Creative
10. In the box below, design a poster that celebrates animal diversity.
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Holt McDougal Biology 2 Invertebrate Diversity
Study Guide A Section 1: Animal Characteristics
Name ______________________________ Class___________________Date__________________
Section 2: Animal Diversity
Study Guide A
KEY CONCEPT
More than 95 percent of all animal species are invertebrates.
VOCABULARY
vertebrate radial symmetry
invertebrate protostome
phylum deuterostome
bilateral symmetry
MAIN IDEA: Each animal phylum has a unique body plan.
Fill in the blank with the word or phrase that best completes the sentence.
1. A vertebrate is an animal with an internal segmented _______________.
Vertebrates make up less than _______________ percent of all known
animal species.
2. Invertebrates are animals without _______________. Invertebrates make up
over _______________ percent of all known animal species.
3. Animals are divided into more than 30 major groups, which are called phyla.
Each group of animals is defined by _______________ and _______________
characteristics.
4. Differences in body plans result from differences in the expression of
_______________ genes.
Circle the word or phrase that best completes the statement.
5. Homeobox (Hox) genes tell embryonic / protostome genes which part of the
body they are going to become, such as the head, middle, or tail.
6. Mutations in a Hox gene can change an animal’s entire body plan. Therefore,
over time, mutations lead to a greater / lower diversity of animal body plans.
7. An increase in oxygen / nitrogen levels in the atmosphere might account for
the development of so many unique body plans during the Cambrian
explosion. As the levels rose, eukaryotic organisms could become more active
and occupy different niches within an ecosystem.
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Holt McDougal Biology 3 Invertebrate Diversity
Study Guide A Section 2: Animal Diversity
Name ______________________________ Class___________________Date__________________
Study Guide A continued
MAIN IDEA: Animals are grouped using a variety of criteria.
For each type of symmetry, complete the description and sketch a picture of an
animal that exhibits that type of symmetry.
Symmetry Description Sketch
8. bilateral Can be divided equally along
____________ plane(s), which splits
an animal into ____________ mirror-
image sides.
9. radial Have body parts arranged in a
____________ around a central axis.
MAIN IDEA: A comparison of structure and genetics reveals the evolutionary
history of animals.
Place the words and phrases from the box into the blanks within the table to show
how protostomes and deuterostomes have different developmental patterns.
Some words may be used more than once.
anus mouth pouches created by folds in the gut tube
radial cleavage spiral cleavage separations in the mesoderm
Protostomes Deuterostomes
10. The first opening of the digestive 14. The first opening of the digestive
cavity develops into the cavity develops into the
____________. ____________.
11. The ____________ is formed 15. The ____________ is formed
second. second.
12. The gut cavity is formed from 16. The gut cavity is formed from
____________________________. ____________________________.
13. Early cell divisions lead to an 17. Early cell divisions lead to an
eight-celled embryo in a twisted eight-celled embryo in an
arrangement called ____________. arrangement called ____________.
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Holt McDougal Biology 4 Invertebrate Diversity
Study Guide A Section 2: Animal Diversity
Name ______________________________ Class___________________Date__________________
Study Guide A continued
Vocabulary Check
Fill in the blank with the word or phrase that best completes the sentence.
18. A phylum is a group of animals defined by ______________ and
______________ characteristics that are different from every other animal
group.
19. The first opening of a protostome’s digestive cavity develops into the mouth,
whereas the second opening of a deuterostome’s digestive cavity develops into
the mouth. Stoma means “mouth.” Therefore, proto- must mean
______________ and deutero- must mean ______________.
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Holt McDougal Biology 5 Invertebrate Diversity
Study Guide A Section 2: Animal Diversity
Name ______________________________ Class___________________Date__________________
Section 3: Sponges and Cnidarians
Study Guide A
KEY CONCEPT
Sponges and cnidarians are the simplest animals.
VOCABULARY
sessile medusa gastrovascular cavity
filter feeder mesoglea
polyp nematocyst
MAIN IDEA: Sponges have specialized cells but no tissues.
Choose the correct term from the box to complete the sentence.
hard muscle parasites sessile
growing nerve predators toxic
1. Sponges lack ___________ and ___________ cells. They are ___________,
meaning they are unable to move from where they are attached.
2. Sponges attach to ______________ surfaces. They secrete _______________
substances that keep other sponges from ______________ into their area and
also protect them from ________________ and _________________.
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Holt McDougal Biology 6 Invertebrate Diversity
Study Guide A Section 3: Sponges and Cnidarians
Name ______________________________ Class___________________Date__________________
Study Guide A continued
Place the following statements in the correct column in the table and in the
correct order to explain the difference between sexual and asexual reproduction
in sponges.
3. a. A bud breaks off an adult sponge.
b. Eggs and sperm are released into the water.
c. Fertilization occurs in the water.
d. The bud attaches to a surface where it grows into an adult.
e. The bud floats in the water.
f. The fertilized egg develops into a free-swimming larva.
g. The larva attaches to a surface where it develops into its adult form.
Sexual reproduction in sponges Asexual reproduction in sponges
___________ ___________
___________ ___________
___________ ___________
___________ ___________
Circle the word or phrase that best completes the statement.
4. A sponge filter feeds by pulling water through tiny holes in its
mouth / body wall. The sponge then strains particles from the water.
5. Sponges are made up of two layers of cells that cover a framework of
collagen-like fibers called spicule / spongin. The skeleton is reinforced with
hard calcium- or silicon-based crystals called spicules / spongins.
Match the types of cells that make up a sponge with their descriptions. The types
of cells are called amoebocytes, choanocytes, and pinacocytes.
6. _________________ are thin and leathery cells that form the sponge’s outer
layer.
7. _________________ are collar cells that form the inner layer of the sponge.
8. _________________ are mobile cells found in the jellylike material
sandwiched between the two cell layers.
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Holt McDougal Biology 7 Invertebrate Diversity
Study Guide A Section 3: Sponges and Cnidarians
Name ______________________________ Class___________________Date__________________
Study Guide A continued
MAIN IDEA: Cnidarians are the oldest existing animals that have specialized
tissues.
Complete the chart with the phrases below and sketch the two cnidarian
body types.
a. mouth and tentacles facing upward
b. mouth and tentacles on the underside
c. cylindrical tubes
d. umbrella-shaped
Body Form Description Sketch
9. polyp
10. medusa
11. Cnidarians can reproduce asexually when the medusa stage / polyp stage buds.
Choose the term from the box that fits the definition of a part of a
cnidarian’s anatomy.
cnidocytes contracting cells mesoglea nerve cells
_________________ 12. These cells interconnect and form a network over the
entire animal. They send sensory information around
the animal and coordinate muscular contractions.
_________________ 13. This is a non-cellular jellylike material.
_________________ 14. These cells cover the surface of a cnidarian and
contain muscle fibers.
_________________ 15. These cells contain stinging structures used for defense
and capturing prey.
Vocabulary Check
Circle the word or phrase that best completes the statement.
16. A nematocyst / mesoglea is a capsule containing a thin, coiled, harpoon-
shaped tubule with a poisonous barb at one end.
17. The gastrovascular cavity is a sac-like space used for digestion / reproduction.
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Holt McDougal Biology 8 Invertebrate Diversity
Study Guide A Section 3: Sponges and Cnidarians
Name ______________________________ Class___________________Date__________________
Section 4: Flatworms, Mollusks, and Annelids
Study Guide A
KEY CONCEPT
Flatworms, mollusks, and annelids belong to closely related phyla.
VOCABULARY
complete digestive tract hemocoel coelom
radula segmentation
MAIN IDEA: Flatworms are simple bilateral animals.
Circle the word or phrase that best completes the statement.
1. Lophotrochozoa is the name of the kingdom / phylum that has flatworms,
mollusks, and annelids.
2. Planarians, flukes, and tapeworms are the three classes / species of flatworms.
3. Flatworms have a solid / hollow body and an incomplete or absent head / gut.
4. Flatworms do not have a circulatory system. They can only move oxygen to
their cells by active transport / diffusion. Therefore, all their cells must be
closer to / farther from the outside environment. This leads to their flat shape.
Fill in the blank with the word or phrase that best completes the sentence.
5. Schistosomiasis is a disease that occurs in ___________. It is caused by
infection from the fluke Schistosoma, which people can contract when they
wade in or drink contaminated ___________.
Use the words from the box to fill in the blanks in the sentence. Some words may
be used more than once.
adult egg flies host larva
6. The life cycle of a tapeworm begins when a(n) ___________ is passed with an
animal’s feces. A(n) ___________ eats the ___________, which develops into
a(n) ___________ within the ___________’s body. Another animal is infected
when it accidentally eats the infected ___________. The ___________
develops into a(n) ___________ in its ___________’s intestines, and the life
cycle begins again.
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Holt McDougal Biology 9 Invertebrate Diversity
Study Guide A Section 4: Flatworms, Mollusks, and Annelids
Name ______________________________ Class___________________Date__________________
Study Guide A continued
MAIN IDEA: Mollusks are diverse animals.
Circle the word or phrase that best completes the statement.
7. A complete digestive tract consists of two openings—a mouth and an anus—at
the same end / opposite ends of a continuous tube.
8. What are the three benefits of having a complete digestive tract?
a. An animal can be more active.
b. An animal can digest food more efficiently.
c. An animal can taste a greater variety of foods.
d. An animal can eat continuously.
e. An animal can find food more easily.
f. An animal can go longer without eating.
Complete the following chart with a description of each of the three shared
anatomical features of mollusks.
Anatomical Feature Description
radula 9. a file-like organ used for
_______________
mantle 10. an area of tissue that covers the
internal _______________
ctenidia 11. flat _______________ found in a
pocket of mantle tissue called the
mantle cavity
Fill in the blank with the word or phrase that best completes the sentence.
12. A hemocoel is part of the circulatory system in a ______________. The
hemocoel consists of spaces between cells within the animal’s tissues.
______________ is pumped through these spaces.
MAIN IDEA: Annelids have segmented bodies.
13. Earthworms, marine mollusks, and leeches are the three groups of
_______________.
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Holt McDougal Biology 10 Invertebrate Diversity
Study Guide A Section 4: Flatworms, Mollusks, and Annelids
Name ______________________________ Class___________________Date__________________
Study Guide A continued
Vocabulary Check
Circle the word or phrase that best completes the statement.
14. The word coelom comes from a Greek word that means “cavity.” Annelids
have a coelem, which is a fluid-filled cavity completely surrounded by muscle.
An annelid uses the coelem to help it to eat / move.
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Holt McDougal Biology 11 Invertebrate Diversity
Study Guide A Section 4: Flatworms, Mollusks, and Annelids
Name ______________________________ Class___________________Date__________________
Section 5: Roundworms
Study Guide A
KEY CONCEPT
Roundworms have bilateral symmetry and shed their outer skeleton to grow.
VOCABULARY
cuticle pseudocoelom
MAIN IDEA: Roundworms shed their stiff outer skeleton as they grow.
Use words from the box to complete the sentence.
bilateral diversity nematodes protostomes
chitin exoskeleton numbers shed
cuticle
1. Roundworms, or ____________, are one of the most numerous kinds of
animals, both in terms of ________________ and in terms of species
_________________.
2. Members of the Ecdysozoa are ________________ (meaning their gut cavity
forms mouth-first), and they have __________________ symmetry.
3. All Ecdysozoans have a tough ______________ called a ________________.
4. The cuticle is made of _______________ and must be ____________
whenever the animal grows larger.
Circle the word or phrase that best completes the statement.
5. A roundworm is cylindrical with a blunt / tapered head and a blunt / tapered
tail. Its body is covered with a tough cuticle made of chitin / lignin, which lies
over a layer of muscle. Muscle within the roundworm is separated from the
rest of the central gut tube by a coelom / pseudocoelom, which is a partially
muscle-lined fluid-filled space. Roundworms have / do not have a digestive
system but they have / do not have circulatory and respiratory systems.
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Holt McDougal Biology 12 Invertebrate Diversity
Study Guide A Section 5: Roundworms
Name ______________________________ Class___________________Date__________________
Study Guide A continued
MAIN IDEA: Many roundworms are parasites.
Complete the following chart with letters for the phrases below. One of the
phrases will be used twice.
a. accidentally swallowing eggs picked up from contaminated surfaces
b. drinking contaminated water
c. in the gut and connective tissues of the host
d. walking barefoot over contaminated soil
e. within the digestive tract of its host
Parasite Where It Is Found: How Infections Occur:
6. hookworm
7. pinworm
8. Guinea worm
Vocabulary Check
Circle the word or phrase that best completes the statement.
9. The prefix pseudo- comes from a Greek word which means “false.” This
relates to the definition of a pseudocoelom, which is a fluid-filled space that is
completely / not completely lined by muscle. It is a false coelom.
Be Creative
10. Design a poster that tells people how to avoid parasitic roundworm infections.
Your design can focus on one or more types of roundworm.
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Holt McDougal Biology 13 Invertebrate Diversity
Study Guide A Section 5: Roundworms
Name ______________________________ Class___________________Date__________________
Section 6: Echinoderms
Study Guide A
KEY CONCEPT
Echinoderms are on the same evolutionary branch as vertebrates.
VOCABULARY
ossicle water vascular system
MAIN IDEA: Echinoderms have radial symmetry.
Use words from the box below to complete the sentence.
arm flexible ossicles stiff
catch connective internal ring canal water
1. All echinoderms have a(n) __________ skeleton made up of many tiny
interlocking calcium-based plates called _____________.
2. The plates are joined together by a unique _________________ tissue with
adjustable stiffness.
3. This tissue lets echinoderms change their consistency, going from very
______________ to very ________________ in a matter of seconds.
4. A water vascular system is a series of ____________-filled canals that extend
along each _____________ from the ______________________ surrounding
the central disk.
Circle the word or phrase that best completes the statement.
5. The water vascular system is a part of the circulatory / digestive system. It is
also used for protection / movement.
Circle the word or phrase that best completes each statement. Then place the
sentences in the correct order to describe how a sea star eats a clam.
6. a. excretes waste material from its anus / mouth
b. grabs the clam with its tube feet / mouth parts and forces open the
clam shell
c. pushes its arms / stomach out of its mouth
d. uses digestive juices from its mouth / ossicles to dissolve the clam’s body
___________________________
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Holt McDougal Biology 14 Invertebrate Diversity
Study Guide A Section 6: Echinoderms
Name ______________________________ Class___________________Date__________________
Study Guide A continued
MAIN IDEA: There are five classes of Echinoderms.
Complete the following chart about each Echinoderm class with use of the
information given below.
Physical description: Feeding method:
a. covered with tiny f. feed on waste matter or
projections or long, sharp graze on algae
spines g. filter feeders
b. fleshy animals with a long h. filter feeders, opportunistic
bilateral shape algae
c. have long, spindly arms feeders, or predators
d. most are sessile, usually i. grazers and sediment feeders
attached to a surface j. scavengers or predators
e. typically have five arms
Physical
Class Description Feeding Method Examples
7. Crinoidea Feather star,
sea lily
8. Asteroidea Sea star
9. Ophiuriodea Brittle star,
basket star
10. Echinoidea Sea urchin,
sea biscuit,
sand dollar
11. Holothuroidea Sea cucumber
Vocabulary Check
Fill in the blank with the word or phrase that best completes the sentence.
12. The term ossicle comes from a Latin word meaning “bone.” This word origin
relates to the definition of an ossicle, which is a tiny interlocking calcium-
based plate that makes up an echinoderm’s internal _______________.
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Holt McDougal Biology 15 Invertebrate Diversity
Study Guide A Section 6: Echinoderms
Name ______________________________ Class___________________Date__________________
Study Guide A continued
Be Creative
13. Create an informative brochure for a tide pool. Include information about all
the different kinds of echinoderms a visitor would find there.
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology 16 Invertebrate Diversity
Study Guide A Section 6: Echinoderms
