chapter 32 part 3
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