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Multiple Choice
Identify the choice that best completes the statement or answers the question.

Refer to the illustration above. Which organism is most closely related to a jellyfish?

a.	1	c.	3
b.	2	d.	4

Which of the following distinguishes sponges from other invertebrates?

a.	They are not motile in any stage of their life cycle.
b.	They obtain nutrients by diffusion rather than by ingestion.
c.	Their cells are not organized into tissues.
d.	They reproduce only asexually.

Sponges

a.	are nonsymmetrical.
b.	lack organization into tissues and organs.
c.	possess cells that are capable of recognizing other sponge cells.
d.	All of the above

Collar cells

a.	are specialized for reproduction.
b.	draw water into the body of a sponge.
c.	produce cytochrome oxidase.
d.	are parasitic protozoa.

Spicules are

a.	flexible protein fibers.
b.	hard spike-like structures in the wall of a sponge.
c.	similar to seeds; a complete sponge can grow from each spicule.
d.	used for taking in food and water.

Adult sponges

a.	have body walls with many pores.
b.	possess true tissues.
c.	are active swimmers.
d.	use stinging cells to capture prey.

Skeletal support in sponges may be provided by

a.	spicules of calcium carbonate.
b.	spicules of silicon dioxide.
c.	fibers called spongin.
d.	All of the above

Sponges obtain food

a.	through photosynthesis.
b.	by using their spicules to paralyze protozoa.
c.	by filtering small organisms from the water.
d.	with their spongin.

In sponges, currents that draw water through the organism are created by

a.	amoebocytes.	c.	gemmules.
b.	collar cells.	d.	spicules.

The cells that move throughout the sponge’s body wall to deliver food to the organism’s cells are called

a.	amoebocytes.	c.	gemmules.
b.	choanocytes.	d.	spicules.

Water leaves the interior of a sponge through the

a.	food vacuoles.	c.	body wall.
b.	spicules.	d.	osculum.

collar cell : water ::

a.	amoebocyte : nutrients and wastes
b.	spongin : food
c.	spicule : water
d.	osculum : mesenchyme

The gemmules of sponges

a.	create water currents for feeding.
b.	are equivalent to the sperm cells of higher animals.
c.	are equivalent to the egg cells of higher animals.
d.	are necessary for one form of asexual reproduction.

Hermaphroditic organisms

a.	reproduce only by asexual means.
b.	produce both eggs and sperm.
c.	have gemmules that are fertilized by amoebocytes.
d.	possess only male amoebocytes.

Hermaphrodism is advantageous in sponges because

a.	they reproduce asexually.
b.	they have gemmules.
c.	they are sessile.
d.	None of the above is true; hermaphrodism does not occur in sponges.

Sponges can reproduce

a.	by the budding of new sponges from the parent.
b.	by a breakup of the original parent into fragments that each become a new sponge.
c.	sexually, using sperm and eggs.
d.	All of the above

some freshwater sponges : gemmules ::

a.	hermaphrodites : eggs and sperm
b.	gemmules : eggs
c.	gemmules : sperms
d.	amoebocytes : eggs

Refer to the illustration above. Which organism captures its prey using nematocysts?

a.	1	c.	3
b.	2	d.	4

Many cnidarians have two distinct life stages,

a.	the gametophyte and the sporophyte.
b.	the polyp and the medusa.
c.	the egg and the adult.
d.	the egg and the larva.

Nematocysts

a.	contain harpoonlike structures called cnidocytes.
b.	create water currents in sponges.
c.	can spear a cnidarian’s prey.
d.	are found in most predatory ctenophores.

The cnidarian’s inner layer of tissue is specialized for

a.	digestion.	c.	capturing prey.
b.	reproduction.	d.	All of the above

The outer cell layer of a cnidarian is the

a.	ectoderm.	c.	endoderm.
b.	mesoglea.	d.	epidermis.

Which of the following is a characteristic associated only with cnidarians?

a.	a digestive tract with a single opening
b.	cnidocytes specialized for defense and capturing prey
c.	choanocytes containing nematocysts
d.	a parasitic life cycle

sponges : fewer than three body layers ::

a.	ctenophores : no body symmetry
b.	sponges : bilateral symmetry
c.	cnidarians : nerve net
d.	cnidarians : choanocytes

The phylum Cnidaria includes all of the following except

a.	jellyfish.	c.	sea anemones.
b.	squids.	d.	corals.

Planula larvae of scyphozoans

a.	result from fertilization of eggs by sperm.
b.	swim freely through the water.
c.	settle to the ocean bottom and grow into polyps.
d.	All of the above

The hydra is unique among the hydrozoans because it

a.	is an active swimmer.
b.	lives in colonies.
c.	is strictly a marine species.
d.	has no medusa stage.

Which of the following is not sessile as an adult?

a.	sponge
b.	coral
c.	sea anemone
d.	Portuguese man-of-war

Sea anemones are

a.	medusae.	c.	larvae.
b.	polyps.	d.	eggs.

The diagram below illustrates the life cycle of the jellyfish.

Refer to the illustration above. Which stage is called a planula?

a.	1	c.	3
b.	2	d.	None of the above

Refer to the illustration above. Which stage reproduces asexually?

a.	1	c.	3
b.	2	d.	None of the above

Anthozoans include

a.	jellyfish.
b.	hydras.
c.	the Portuguese man-of-war.
d.	sea anemones and corals.

Scyphozoans, such as jellyfish, spend most of their lives as

a.	polyps.	c.	corals.
b.	medusae.	d.	parasites.

The class of cnidarians that typically live only as polyps is the

a.	Anthozoa.	c.	Scyphozoa.
b.	Hydrozoa.	d.	None of the above

Which of the following is not a characteristic of ctenophores?

a.	bioluminescence
b.	movement by means of beating cilia
c.	use of cnidocytes to capture prey
d.	hermaphrodism

Completion
Complete each statement.

____________________ is drawn into a sponge through pores and leaves through the osculum.

A network of tough, flexible protein fibers called ____________________ provides support in some sponges.

Spike-like objects that make up the skeleton of some sponges are called ____________________.

A sponge’s ____________________ may be composed of either calcium carbonate or silicon dioxide.

Food molecules are carried throughout a sponge’s body by ____________________.

Food-filled balls of amoebocytes that are involved in asexual reproduction in sponges are called ____________________.

An organism that produces both eggs and sperm is called a(n) ____________________.

A free-floating, gelatinous body form of a cnidarian is called a(n) ____________________, while an attached body form is called a(n) ____________________.

Cnidarians have two cell layers, the epidermis and the ____________________.

A coral is a member of the class ____________________.

Ctenophores are the largest organisms that move by the beating of ____________________.