Biol 3840: Chp 13 - Cnidaria & Ctenophora

Place the following steps in the typical cnidarian life cycle in chronological order, with the step following the formation of the zygote at the top of the list.

1. Development into a motile planula larva 2. Settlement onto a hard surface 3. Metamorphosis into a polyp 4. Production of medusae through asexual reproduction

Dimorphism occurs when an organism has what number of morphological types?

2

Select all of the characteristics of sea anemones. A. A structure called a siphonoglyph draws water into the animal through the movement of cilia. B. They use pedal discs to attach to submerged objects. C. They are relatively large polyps, especially compared to those of hydrozoans. D. They are generally drab in coloration to blend in to their surroundings for defense.

A. A structure called a siphonoglyph draws water into the animal through the movement of cilia. B. They use pedal discs to attach to submerged objects. C. They are relatively large polyps, especially compared to those of hydrozoans.

Which of the following statements are true about sponges? A. Adult sponges do not have distinct cell layers. B. Sponges are not diploblastic. C. Sponges are not true animals. D. Sponges are not asymmetric.

A. Adult sponges do not have distinct cell layers. B. Sponges are not diploblastic.

Sea anemones reproduce through which of the following methods? Select all that apply. A. Asexually via fission B. Sexually by strobilation C. Sexually with separate sexes D. Sexually with hermaphroditic individuals E. Asexually via pedal laceration

A. Asexually via fission C. Sexually with separate sexes D. Sexually with hermaphroditic individuals E. Asexually via pedal laceration

Which of the following are true of reproduction in hydras? A. Budding occurs when outpocketings of the body wall develop into offspring. B. They reproduce both sexually and asexually. C. Most species are monoecious. D. Zygotes undergo holoblastic cleavage to form a hollow blastula.

A. Budding occurs when outpocketings of the body wall develop into offspring. B. They reproduce both sexually and asexually. D. Zygotes undergo holoblastic cleavage to form a hollow blastula.

Select all of the characteristics of members of subclass Octocorallia. A. Eight pinnate tentacles B. A solitary lifestyle C. An endoskeleton D. Eight unpaired, complete septa E. A siphonoglyph

A. Eight pinnate tentacles C. An endoskeleton D. Eight unpaired, complete septa

Select all of the habitats where cnidarians may occur. A. Freshwater ponds and lakes B. At great depths in the ocean C. Attached to shells of marine animals D. On rocks and wharves in marine environments E. Moist terrestrial soil

A. Freshwater ponds and lakes B. At great depths in the ocean C. Attached to shells of marine animals D. On rocks and wharves in marine environments

Sea anemones can move in which of the following ways? A. Gliding along the substrate on their pedal discs B. Swimming by flattening their tentacles and using them as oars C. Contracting and withdrawing their tentacles and oral discs for defense D. Expanding their bodies and tentacles in search of food

A. Gliding along the substrate on their pedal discs C. Contracting and withdrawing their tentacles and oral discs for defense D. Expanding their bodies and tentacles in search of food

Select all of the characteristics of members of class Scyphozoa. A. Lappets and rhopalia occurring at marginal notches B. A scalloped bell margin, with the number of notches ranging from 4 to 16 C. A medusa bell that typically ranges from 2 to 40 cm in diameter D. Mesoglea layer thin or absent and unbranched gastrovascular cavity

A. Lappets and rhopalia occurring at marginal notches B. A scalloped bell margin, with the number of notches ranging from 4 to 16 C. A medusa bell that typically ranges from 2 to 40 cm in diameter

Which of the following accurately describe locomotion in ctenophores? A. Most use ciliated comb plates to propel themselves forward. B. In calm water, many species rest vertically with little movement. C. Many species can pulsate to alternately draw water in and out of the body and create a weak form of jet propulsion. D. Some forms are sessile or creeping rather than free-swimming. E. They are often at the mercy of tides and strong currents.

A. Most use ciliated comb plates to propel themselves forward. B. In calm water, many species rest vertically with little movement. D. Some forms are sessile or creeping rather than free-swimming. E. They are often at the mercy of tides and strong currents.

Select all of the following that describe the cnidarian nervous system. A. Nerve net B. Includes a rudimentary brain C. Networks of nerve cells occur at the bases of both the epidermis and gastrodermis D. Transmission across the synapse can occur only in one direction E. Myelin occurs on the axons for insulation

A. Nerve net C. Networks of nerve cells occur at the bases of both the epidermis and gastrodermis

Which of the following statements are TRUE regarding cnidarian feeding and digestion? A. Polyps are usually carnivorous. B. Some forms, such as corals, are able to supplement their diet with the products of photosynthesis. C. Most polyps capture tiny zooplankton using ciliary action. D. Extracellular digestion begins in the mouth in all cnidarian species. E. The mouths of both hydromedusae and scyphomedusae are found at the end of a manubrium.

A. Polyps are usually carnivorous. B. Some forms, such as corals, are able to supplement their diet with the products of photosynthesis. E. The mouths of both hydromedusae and scyphomedusae are found at the end of a manubrium.

Radiate animals have which of the following characteristics? A. Presence of a gut cavity B. The process of gastrulation during development C. An asymmetric body plan D. A body comprised of a nonlayered aggregate of various cell types E. Two embryonic cell layers (endoderm and ectoderm)

A. Presence of a gut cavity B. The process of gastrulation during development E. Two embryonic cell layers (endoderm and ectoderm)

Select all of the benefits provided by zooxanthellae to corals. A. Recycling of phosphorus-containing wastes B. Food through the process of photosynthesis C. Recycling of nitrogenous wastes D. Facilitation of calcium carbonate deposition E. Coloration for communication among colonies F. Defense through the production of toxins

A. Recycling of phosphorus-containing wastes B. Food through the process of photosynthesis C. Recycling of nitrogenous wastes D. Facilitation of calcium carbonate deposition

Ctenophore prey capture and feeding can occur in which of the following ways? A. Small prey items are collected by cilia on the body surface. B. Portions of a prey item may be consumed. C. Large prey items are incapacitated by discharging nematocysts that inject toxin. D. An adhesive substance secreted by colloblasts on the surface of tentacles captures small prey items.

A. Small prey items are collected by cilia on the body surface. B. Portions of a prey item may be consumed. D. An adhesive substance secreted by colloblasts on the surface of tentacles captures small prey items.

Select all of the true statements regarding typical cnidarian body structure. A. The epidermis is derived from ectoderm. B. The gastrodermis is derived from ectoderm. C. The epidermis lines the gut cavity. D. The mesoglea lies between the epidermis and the gastrodermis. E. The gastrodermis is an inner layer.

A. The epidermis is derived from ectoderm. D. The mesoglea lies between the epidermis and the gastrodermis. E. The gastrodermis is an inner layer.

Select all of the following that describe the life cycle of a typical colonial hydrozoan. A. The zygote develops into a free-swimming planula larva. B. Gametes arise in an organ called the hydranth. C. New feeding polyps are produced through the process of budding. D. The larval stage develops directly into a sexually reproducing medusa.

A. The zygote develops into a free-swimming planula larva. C. New feeding polyps are produced through the process of budding.

Select all of the characteristics of common hydras. A. Their mouth is on oral end surrounded by hollow tentacles. B. They are solitary polyps. C. They live in freshwater habitats, such as clean pools and streams. D. They exist in a medusa stage only. E. They attach to substratum by pedal disc.

A. Their mouth is on oral end surrounded by hollow tentacles. B. They are solitary polyps. C. They live in freshwater habitats, such as clean pools and streams. E. They attach to substratum by pedal disc.

Characteristics of the hexacorallian corals include A. interconnected gastrovascular cavities of polyps. B. a siphonoglyph that pulls water into the animal. C. a gastrovascular cavity that is divided into chambers in multiples of six. D. a pedal disc that connects the animal and its exoskeleton. E. secretion and inhabitation of calcareous structures that can become massive over time.

A. interconnected gastrovascular cavities of polyps. C. a gastrovascular cavity that is divided into chambers in multiples of six. E. secretion and inhabitation of calcareous structures that can become massive over time.

Members of what cnidarian class are solitary or colonial marine polyps that lack a medusa stage?

Anthozoa

Select all of the characteristics of a typical cnidarian polyp. A. Presence of ocelli, and a velum B. Asexual reproduction through budding, fission, or pedal laceration C. An inverted bowl shape D. A gastrovascular cavity E. A mouth surrounded by tentacles at the oral end of the body F. Attachment to the substratum by a pedal disc or similar structure

B. Asexual reproduction through budding, fission, or pedal laceration D. a gastrovascular cavity E. A mouth surrounded by tentacles at the oral end of the body F. Attachment to the substratum by a pedal disc or similar structure

Which of the following are characteristics of both radiate phyla, Cnidaria and Ctenophora? A. Polyp and medusa body forms B. Development of distinct cell layers C. Cnidocytes D. Presence of an endoderm E. Diploblastic development F. Gastrulation

B. Development of distinct cell layers D. Presence of an endoderm E. Diploblastic development F. Gastrulation

Select all of the following that are contained in the rhopalia of scyphomedusae and cubozoan medusae. A. Sperm B. Ocelli C. Statocysts D. Eggs E. Chemoreceptors F. Nematocysts

B. Ocelli C. Statocysts E. Chemoreceptors

Select all of the characteristics of members belonging to class Hydrozoa. A. All occur in freshwater habitats. B. Some lack a medusa stage in the life cycle. C. Most are colonial in form. D. The polyp stage is usually asexual.

B. Some lack a medusa stage in the life cycle. C. Most are colonial in form. D. The polyp stage is usually asexual.

Select all of the characteristics of members of class Anthozoa. A. Both polyp and medusa stages occur in the life cycle. B. They can be solitary or colonial. C. They all have a hexamerous body plan. D. Many forms produce a skeleton for support. E. The gastrovascular cavity is partitioned by septa.

B. They can be solitary or colonial. D. Many forms produce a skeleton for support. E. The gastrovascular cavity is partitioned by septa.

Match each mode of asexual reproduction in cnidarians with its description. Budding --> Fission --> Pedal laceration --> Options: - A polyp divides in half and one side of the polyp pulls away from the other side - Tissue torn from the basal disc develops into tiny new polyps - Tissue on the side of a polyp develops into another polyp that stays attached to the parent polyp

Budding --> Tissue on the side of a polyp develops into another polyp that stays attached to the parent polyp Fission --> A polyp divides in half and one side of the polyp pulls away from the other side Pedal laceration --> Tissue torn from the basal disc develops into tiny new polyps

Select all of the characteristics of members of the phylum Ctenophora. A. Distinct cephalization B. A medusa stage C. Biradial symmetry D. Eight comblike rows of cilia E. Colloblasts

C. Biradial symmetry D. Eight comblike rows of cilia E. Colloblasts

What orders include the highly specialized hydrozoans that often form polymorphic swimming or floating colonies containing modified medusae and polyps? A. Hydroida B. Stylasterina C. Chondrophora D. Siphonophora

C. Chondrophora D. Siphonophora

Select all of the characteristics of members of the cnidarian class Cubozoa. A. They are mostly free-floating, weak swimmers. B. The margin of the umbrella is scalloped, with a pair of lappets occurring in each notch. C. The edge of the subumbrella turns inward to form a velarium. D. Each rhopalium contains six eyes. E. The base of a tentacle is differentiated into a flattened, tough blade called a pedalium.

C. The edge of the subumbrella turns inward to form a velarium. D. Each rhopalium contains six eyes. E. The base of a tentacle is differentiated into a flattened, tough blade called a pedalium.

Cnidocytes produce one of twenty different types of organelles called _______________________, one of which is a nematocyst.

Cnidae or Cnida

Unlike sponges and placozoans, members of the phyla ________________and ___________ are diploblastic and undergo gastrulation during development.

Cnidaria; Ctenophora

Match each cnidocyte-related structure with its description. Cnidoblast --> Cnida --> Operculum --> Cnidocil --> Options: - Covers over the end of cnidae within cnidocytes - Choice, Tiny capsule containing a coiled thread or filament Tiny capsule containing a coiled thread or filament - A triggerlike structure that causes the specialized organelles of cnidocytes to discharge - A developing cnidocyte

Cnidoblast --> A developing cnidocyte Cnida --> Tiny capsule containing a coiled thread or filament Operculum --> Covers over the end of cnidae within cnidocytes Cnidocil --> A triggerlike structure that causes the specialized organelles of cnidocytes to discharge

Biradial marine animals that typically use eight rows of cilia for locomotion are members of what taxonomic group?

Ctenophora

Members of what cnidarian class are characterized by a dominant medusa form, with the bell being almost square in transverse section and tentacles or groups of tentacles situated at each corner of the square?

Cubozoa

An organism that has only two embryonic cell layers (endoderm and ectoderm) is

Diploblastic

A diploblastic organism develops from what embryonic cell layers?

Endoderm and ectoderm

True or false: Unlike many other solitary cnidarian polyps, sea anemones are cemented in place by an adhesive substance exuded by the pedal disc that makes them unable to move to a new location after the larva attaches to the substrate.

False Reason: Sea anemones are not cemented in place; they are able to glide along the substrate on their pedal discs.

Sea anemones often form mutualistic relationships with other organisms. What organism receives protection against predators from the anemone and in turn provides the anemone with free transportation and scraps of food?

Hermit crabs

What organism can be described as a solitary freshwater polyp that attaches to the undersides of submerged vegetation via a pedal disc and has an impressive capacity for stretching and contraction?

Hydra

Match the following characteristics related to feeding and digestion to the cnidarian group that exhibits those characteristics. Hydra --> Colonial hydrozoan polyps --> Hydromedusae --> Anthozoan polyps -->

Hydra --> The tentacle cavity communicates with the gastrovascular cavity; extracellular digestion occurs in the gastrovascular cavity and intracellular digestion occurs in the gastrodermis Colonial hydrozoan polyps --> Digestion begins in the mouth, which faces upward into the water column; a digestive broth is passed to the gastrovascular cavity, where intracellular digestion occurs in the cells lining it Hydromedusae --> Digestion begins in the mouth, which faces downward at the end of a manubrium; a digestive broth is passed to the gastrovascular cavity, where intracellular digestion occurs in the cells lining it Anthozoan polyps --> Tentacles expand to search for prey such as small fish and invertebrates, which are then carried to the mouth; may use ciliary action for prey capture or zooxanthellae for nutrition

In hydrozoans, what feature lends support to the body and allows longitudinal extension of the body and tentacles?

Hydrostatic skeleton

What cnidarian class is characterized by an asexual polyp stage with a sexual medusa stage, and often occurs in marine habitats and in a colonial form?

Hydrozoa

Scyphomedusae use these four structures formed by the manubrium to capture and ingest prey items.

Oral arms

Members of what cnidarian class have the following characteristics: a medusa stage ranging from 2 cm to 2 m in diameter, a bell that lacks a velum and can vary from a shallow saucer shape to a deep helmet or goblet shape, and sense organs called rhopalia?

Scyphozoa

The medusa of members of what cnidarian class has a scalloped margin, with each notch bearing a pair of lappets and between them a rhopalium with statocysts, sensory epithelium, and possibly ocelli?

Scyphozoa

What cnidarian often enters into mutualistic relationships with other organisms including dinoflagellates, hermit crabs, and damselfishes?

Sea anemones

Which of the following best describes reproduction in scyphozoans?

Sexes are separate and fertilization is internal.

What are cnidocytes?

Specialized stinging cells found in cnidarians that are used in prey capture and defense

What statement is true regarding the dimorphic nature of cnidarians?

The polyp stage is sessile, while the medusa stage is free-swimming/floating.

What statement describes siphonophores?

They usually form floating colonies of modified medusae and polyps.

True or false: Cnidarians occur in both marine and freshwater habitats.

True

Which of the following best describes the scyphozoan nervous system?

Two interconnected nerve nets; the subumbrellar net controls bell pulsations and the other is more diffuse and controls local functions

Gastrulation can be described as

a process of embryonic development in which the cell layers of animals are produced.

Widespread coral bleaching is currently occurring at an unprecedented rate and is correlated with

a rise in ocean temperature.

The expulsion of zooxanthellae from coral tissues that can occur as ocean temperatures increase is called coral ______________.

bleaching

Asexual reproduction in hydras occurs through the process of ________________.

budding

The asexual reproductive process involving tissue on the side of a polyp developing into another functioning polyp is known as _________________; if the new polyp stays attached to the parent polyp, a(n) ___________________is formed.

budding; colony

Tiny organelles contained within cnidocytes are called _____________.

cnida

Members of the phylum Cnidaria possess cells known as ______ that produce stinging organelles called ______ for defense.

cnidocysts; cnidae

In ctenophores, the epidermal cells that secrete a sticky, adhesive substance used in prey capture are known as _____________ .

colloblasts

In order to capture prey, many ctenophores trail their two long tentacles in the water, and small planktonic prey items adhere to the adhesive cells called ________________.

colloblasts

Free-swimming ctenophores are able to propel themselves forward with the help of eight rows of ______________ plates.

comb

The term for an organism having two morphological types is ________________.

dimorphism

Zooxanthellae are mutualistic __________________ often found in cnidarian tissues that supply the animal with food molecules derived from the process of ____________________.

dinoflagellates; photosynthesis

The stomach of scyphomedusae has four extensions called ____________________ that house nematocyst-covered, tentacle-like projections of the gastrodermis called _______________ filaments.

gastric pouches; gastric

The stage of embryonic development known as ___________________ produces the cell layers of adult animals.

gastrulation

Relatively small polyps with a gastrovascular cavity divided into multiples of six that inhabit calcareous cups that they have secreted are

hexacorallian corals.

In hydrozoans, support and longitudinal extension of the body are achieved through the ______________ skeleton, created when the beating of cilia on the nutritive-muscular cells brings water into the ________________ cavity.

hydrostatic; gastrovascular

The margin of the scyphozoan medusa bell is scalloped, with each notch bearing a pair of lobe-like projections called ____________. Between these lies a sense organ called a ______________ .

lappets; rhopalium

Some ctenophores, flatworms, and molluscs consume hydroids bearing __________________, then store and use these stinging structures for their own defense.

nematocyst

The most common type of cnida that is used to inject a toxin for prey capture and defense is a _______.

nematocyst

What type of cnidarian structure can be described as a tiny capsule composed of a material similar to chitin containing a coiled filament that may bear tiny barbs?

nematocyst

The diffuse nervous system of cnidarians can best be described as a

nerve net

The sensory structures of hydroid medusae that are responsible for light reception are _____.

ocelli

In a typical cnidarian life cycle, a newly formed zygote develops into a motile ___________________larva, which then settles onto a hard surface to develop into a ________________.

planula; polyp

In the life cycle of a typical colonial hydrozoan, a zygote produces a ciliated ________________ , which eventually settles onto the substratum to become a minute _________________,

planula; polyp

Within certain cnidarian colonies, a polyp may be able to reproduce asexually to form new individuals with different morphologies. Such colonies are _______.

polymorphic

If a cnidarian colony is ___________________, it is made up of polyps with a number of different morphologies.

polymorphism

Unlike the medusa form, a typical cnidarian ______________ has a body that is tubular in shape with a mouth surrounded by tentacles and a pedal disc or similar structure at the aboral end.

polyp

Cnidarians are dimorphic; the larval or _______________ form is sessile and attached to the substrate with tentacles extended into the water column, and the adult or ___________________ form is umbrella-shaped and adapted for a floating, free-swimming lifestyle.

polyp; medusa

Monoecious sea anemone species are ____________________ , meaning that they produce sperm before producing eggs.

protandrous

In some cnidarian medusae, chemoreceptors, statocysts, and often ocelli are grouped at the margin of the bell in sense organs called ________.

rhopalia

What organism is best described as a relatively large polyp with a crown of tentacles arranged in one or more circles around the mouth of a flat oral disc?

sea anemone

A velum is a

shelflike fold of tissue found in hydromedusae that functions in swimming.

The polyps of most octocorallian colonies are able to communicate through a series of gastrodermal tubes called ________________.

solenia

Colloblasts are __________.

specialized cells of ctenophores that secrete an adhesive substance used in prey capture

Two major sensory structures found in hydroid medusae are the ____________________, which are responsible for maintaining equilibrium within the water column, and the ocelli, which function in the reception of _____________________.

statocyst; light

The scyphozoan nervous system consists of two nerve nets; the _____________net controls bell pulsations for swimming, and another more diffuse net controls more local reactions such as feeding and defense.

subumbrellar

Hydroid medusae differ from scyphomedusae because the hydroid medusae possess

velum

Corals rely on their relationship with ______ for food, recycling of phosphorus and nitrogenous wastes, and assistance in the deposition of calcium carbonate.

zooxanthellae

Mutualistic symbiotic dinoflagellates that inhabit gastrodermal cells and supply the cnidarian with products of photosynthesis are known as:

zooxanthellae