chapter 32 part 3

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Order the major events in a generalized life cycle of a cnidarian as they occur starting with gamete formation at the top.

1. gamete formation of the medusa form 2. fertilization 3. development of a planula larva 4. polyp formation 5. asexual production of medusae

How are colonies formed in cnidarians?

A polyp produces new polyps asexually and they all remain attached to one another, forming a colony.

Which of the following are characteristics of hard corals?

An exoskeleton of calcium carbonate Polyp form is dominant Symbiotic photosynthetic zooxanthellae

What cnidarian class contains solitary or colonial polyps with hollow tentacles and mesenteries that compartmentalize the gastrovascular cavity?

Anthozoa

Within phylum Cnidaria, the class that includes the most species is

Anthozoa

How are coral reefs formed?

As an individual or a colony of corals grows, dead calcium carbonate skeletons accumulate below it, forming the coral reef.

In certain cnidarian life cycles where both body forms exist, how are medusae produced?

Asexually, from polyps

Choose the two main type of symmetry found in eumetazoans.

Bilateral symmetry Radial symmetry

This group of animals is characterized by a transition to bilateral symmetry.

Bilateria

Some soft corals can secrete needles of ___ ___. Because they are embedded in their tissues, those needles can provide protection against ___

Blank 1: calcium Blank 2: carbonate Blank 3: predation or predators

Coral reefs have great economic importance, because they serve as refuges for the young of many ___ and ___ that are eaten by humans; in addition they protect the coasts of many tropical islands.

Blank 1: crustaceans Blank 2: fishes or fish

In eumetazoans, the embryonic ectoderm gives rise to the ___ and nervous system, the embryonic ___ forms the muscles, and the embryonic ___ develops into the gastrodermis.

Blank 1: epidermis Blank 2: mesoderm Blank 3: endoderm

In ___ digestion, food particles must be small enough to be engulfed and digested by cells whereas in ___ digestion, larger food items are first broken down with digestive enzymes before the particles are engulfed by cells.

Blank 1: intracellular Blank 2: extracellular

The ___ form of cnidarians is free-swimming and umbrella-shaped, with a mouth on the concave underside that is surrounded by ___

Blank 1: medusa Blank 2: tentacles

Cnidarians use ___ in prey capture and defense.

Blank 1: nematocysts

Cnidarians may exist as either ___ or , or ___ they may alternate between both phases during their life cycle.

Blank 1: polyps Blank 2: medusae

The two main types of symmetry found in eumetazoans are ___ symmetry and ___ symmetry

Blank 1: radial Blank 2: bilateral

One way in which climate change affects corals is that water that is ___ than usual can cause the symbiosis of corals with zooxanthellae to break down; this leads to coral ___

Blank 1: warmer or hotter Blank 2: bleaching

Some soft corals can secrete needles embedded in their tissue which can serve to protect those animals from predators. What are those needles made of?

Calcium carbonate

Select characteristics of the mesoglea of cnidarians.

Can contain many cells Can be acellular Found between the epidermis and the gastrodermis

Members of what phylum are characterized by a diploblastic, radially symmetrical body plan and, while not having organs and organ systems, possess distinct tissues?

Cnidaria

The largest class of ___ is Anthozoa.

Cnidaria

What organisms are included in the phylum Ctenophora?

Comb jellies

Which of the following are characteristics of members of class Anthozoa?

Compartmentalization of the gastrovascular cavity by mesenteries Tentacles are hollow

Which of the following are negative effects of climate change on corals?

Coral bleaching (loss of zooxanthellae) can occur if water is warmer than usual. Higher CO2 in the atmosphere leads to lower pH in the ocean water which makes calcium-carbonate less available for corals.

Comb jellies make up the phylum

Ctenophora

The animal phylum that includes members that are often bioluminescent, live in marine environments, and use cilia for movement and colloblasts for prey capture is

Ctenophora

Cnidarians known as box jellies are part of what class?

Cubozoa

In what capacities do nematocysts function?

Defense Prey capture

What clade includes all animals that have true tissues and body symmetry?

Eumetazoa

In contrast to Parazoa, the ___ includes all animals that have true tissues and body symmetry.

Eumetazoa or eumetazoans

True or false: The two different body forms of cnidarians are different in almost all aspects of their shape and function.

False

Which of the following are carried out in the gastrovascular space of cnidarians?

Gamete production (in most species) Digestion Waste discharge Gas exchange

What is the name of the digestive tissue that develops from the embryonic endoderm in eumetazoans?

Gastrodermis

What organisms are solitary, freshwater cnidarian polyps with no medusa stage that can glide, somersault, or float to new locations?

Hydra

Organisms within the class include Hydra and the Portugese-man-of-war.

Hydrozoa

What cnidarian class contains members that exhibit both the polyp and medusa stages of the life cycle, may be solitary or colonial, and may live in freshwater?

Hydrozoa or hydroids

Where do the gametes of an anthozoan polyp form?

In the mesenteries

Which of the following best describes why the appearance of extracellular digestion in cnidarians was an important step in the evolution of animals?

It allowed cnidarians to eat food that is larger than an individual cell.

Which of the following statements about extracellular digestion is NOT true?

It is the main method of digestion used by sponges.

What are the functions of a hydrostatic skeleton in animals lacking a skeleton of shell or bone?

It provides a rigid structure against which muscles can operate. It gives shape to the animal.

Dispersal in cnidarians is achieved during what phase/phases of the life cycle?

Larvae and medusa

Which of the following accurately describes mesenteries in anthozoan polyps?

Longitudinal sheets of tissue that compartmentalize the gastrovascular cavity

Select the main body form found in class Cubozoa.

Medusa

Which of the following lies between the epidermis and the gastrodermis of cnidarians?

Mesoglea

Which of the following statements regarding the two body forms in the life cycle of cnidarians is true?

Most species have both forms, but some species may not have either a medusa or a polyp form.

What cellular structures are considered to be the most complex structures secreted by single animal cells?

Nematocysts

Which term refers to the unique stinging intracellular structures of cnidarians?

Nematocysts

___ which are also referred to as "stinging cells," are the most complex structures secreted by single animal cells.

Nematocysts

Despite their morphological similarities, molecular evidence suggests that acoel flatworms are not related to flatworms in the phylum

Platyhelminthes

In which phylum were acoel flatworms previously classified?

Platyhelminthes

What cnidarian form is characterized by a cylindrical body with a mouth surrounded by tentacles at the end of the cylinder opposite where it is attached to substrate or colonial tissue?

Polyp

In cnidarians, asexual reproduction in polyps can produce what phases of the life cycle?

Polyps and medusae

Consider a cnidarian, which forms both a polyp and a medusa stage. Which of the following statements about the life cycle of such a cnidarian are TRUE?

Polyps are sessile Medusae are free-swimming

Which of the following organisms are members of Class Hydrozoa?

Portuguese man-of-war Hydra

Jellyfish are members of the cnidarian class

Scyphozoa

The organism shown in this figure is a member of what class?

Scyphozoa

Which of the following are members of class Anthozoa?

Sea fans Stony corals Sea pansies Sea anemones

Which of the following are true of members of class Hydrozoa?

Some members live in freshwater Some are bioluminescent

Star jellies are members of the ___ class.

Staurozoa

What are cnidae?

Stinging capsules other than nematocysts found in certain cnidarians.

In cnidarians, what is a medusa?

The free-swimming form that is umbrella-shaped with a mouth on the concave underside, surrounded by tentacles

Which of the following are characteristics of members of class Scyphozoa?

The medusa is the major body form, with the polyp being greatly reduced or even absent in some species. They move by jetting water from the gastrovascular cavity or space beneath it, using the rhythmic contraction of muscles.

In cnidarians that exhibit both polyp and medusa in the life cycle, how are gametes typically formed?

The medusa produces both sperm and eggs.

Which of the following accurately describes reproduction in cnidarian species which do not have a medusa form?

The polyp form produces gametes and the resulting planula develops directly into a polyp

Choose all characteristics of acoel flatworms.

Their mouth leads to a solid digestive syncytium. They do not have a coelom. They have bilateral symmetry.

Which of the following are characteristics of cnidarians?

They are diploblastic. They are made of distinct tissues. They have radial symmetry

Which of the following accurately describes why ctenophores are no longer considered closely related to cnidarians?

They lack nematocysts. They have muscle cells derived from mesoderm. They are structurally complex.

Which of the following are characteristics of ctenophores?

They move by coordinated beating of cilia. They possess colloblasts for prey capture. Many species are bioluminescent.

Which of the following are reasons why corals are economically very important to humans?

They protect the coastal regions of many tropical islands. They serve as refuge sites for the young of many crustaceans and fishes eaten by humans.

Which of the following is true of the two body forms found in cnidarians (polyp and medusa)?

They share the same basic morphology - mouth, gastrovascular cavity, and tentacles.

How do ctenophores move?

They use the beating of their cilia.

How many nematocytes are typically found in the tentacle of a cnidarian?

Thousands

How many clades does the Bilateria comprise?

Two

Which of the following accurately describes the number of body forms exhibited by most cnidarians?

Two

Stony corals, sea anemones, sea fans, sea whips, sea pansies, and sea pens are all members of what class in phylum Cnidaria?

anthozoa

Coral reefs are formed as individual or colonial polyps grow upward leaving a dead exoskeleton of ___ ___ accumulating under it.

calcium carbonate

Ctenophores use eight rows of comb-like plates of fused ___ to propel themselves in the water column.

cilia

Some cnidarians possess stinging capsules of types other than nematocysts. These other types of stinging capsules are collectively termed

cnidae

Ctenophores were formerly thought to be related to ___ because of their gelatinous, medusa-like form.

cnidarians

As their name implies, flatworms in the phylum Acoela lack

coeloms

In many cnidarian species, the polyp produces other polyps asexually; if they remain attached to one another, they form a group that is referred to as a(n)

colony

The evolution of extracellular in cnidarians is significant because it allowed them to feed on food particles that were larger than their cells.

digestion

Match each embryonic germ layer in eumetazoans to the tissues to which it gives rise.

ectoderm = epidermis and nervous system endoderm = gastrodermis mesoderm = muscles

The outer covering of the animal body is the ______.

epidermis

Hard corals secrete an ___ of calcium carbonate around themselves. These animals can form coral reefs in shallow waters in the tropics, because they contain symbiotic photosynthetic ___

exoskeleton, dinoflagellates

In eumetazoans, digestive tissue that develops from the embryonic endoderm is known as the

gastrodermis

Although nematocysts typically occur in the tentacles of cnidarians, they may also be found in the ___ cavity where they aid in digestion.

gastrovascular

The ___ cavity of cnidarians is the site of digestion, gas exchange, waste discharge, and, in many species, gamete formation.

gastrovascular

The freshwater ___ is a solitary Cnidarian with no medusa stage and is capable of moving to a new surface by gliding, somersaulting or floating.

hydra

In cnidarians, dispersal occurs in ___ and ___

larvae, medusae

The polyp form of cnidarians has a tubular body with a ___ that is surrounded by ___

mouth, tentacles

A hydrostatic skeleton serves two main functions: it provides a rigid structure against which ___ can operate and it gives the animal ___

muscles, shape

The unique stinging intracellular structures that assist a typical cnidarian in defense and prey capture are known as

nematocysts

In cnidarians, a zygote develops into a planktonic ciliated ___ larva that metamorphoses into a polyp.

planula

In cnidarians, the planktonic ciliated larva that metamorphoses into a polyp is known as a(n) ______.

planula

Most cnidarians exist as two different body forms: the ___ and the ___

polyp, medusa

Members of what cnidarian class have a relatively conspicuous and complex medusa stage, propel themselves through water using rhythmic contraction of muscles, and are very unlikely to kill a human through stinging by nematocysts?

scyphozoa

Soft-bodied, muscular anthozoans that can live in waters of all depths throughout the world and range from a few millimeters to over a meter in diameter are ______.

sea anemones

The organism shown in this figure is a member of a small group of highly muscular, soft-bodied anthozoans called

sea anemones

Members of which cnidarian class form planula larvae that creep rather than swim or drift?

staurozoans


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