Zoology Unit 2 - Phylum Cnidaria

Explain the life cycle of the Cidarian Aurelia.

- Adult medusa release planula after genetic recombination - planula lands on floor and becomes strobula (**) - strobula buds off top end - ephyra (**) is bud that swims off - ephyra grows into adult medusa

Explain the lifecycle of the Cnidarian Obelia.

- Colonial adult lets off medusa bud - external sexual reproduction between male & female medusa - planula settles on bottom of ocean - forms young colony with hydranth (feeder bud) first -grows to adult colony

Describe the skeletal system in a Cnidarian.

- Hydrostatic skeleton in small soft-bodied types - Calcium carbonate skeletons in corals - Rigid protein endoskeleton in many anemones

Describe the Cnidarian nervous system.

- a nerve net covers the body - composed of interconnected neurons, but with no centralization (no brain) - all reactinos are reflexes but can be shared with other regions

What are the characteristics of the Cnidarian Class Cubozoa.

- box jellies, bell shaped like a box - most have only 4 tentacles - fast swimmers & good "vision" (due to multiple ocelli all over bell) - very predatory - no alternation of generation - Biolumenescence - have a pedalium

What are the characteristics of the Cnidarian Class Scyphozoa.

- cup animals, true jellyfish - half have alternation of generations with medusa as dominant in lifecycle, internal fertilization - motile - 95% water - thick mesoglea layer - has rhopalium for best sensory (**) - most complex arrangement of GVC - gastric pouches (**) - feed on plankton and have short lumpy tentacles

What are the characteristics of the Cnidarian Class Anthozoa.

- flower animals - most plant-like in shape and color - no medusa stage - no alternation of generations - all are marine - most have skeleton of calcium or protein

Describe the Cnidarian digestive system.

- incomplete (only one opening - no anus) - food captured in GVC lined with gastrodermis - digestion is intracellular - NO DIGESTIVE ORGANS

What are the characteristics of the Cnidarian Class Hydrozoa.

- mostly marine colonial polyps like Obelia - most display alternation of generations - except Hydra which is only polyp - obligate medusae include most freshwater jellyfish like Goneonemis

explain how a cnidocyte fires it's nematocyst.

- nematocyst fires based on water pressure. - starts inside out then fires filament outward

Describe the Cnidarian endocrine system.

- neurons release ormones into cells to produce various responses - no endocrine glands

Describe sexual reproduction of cnidarians.

- primarily seen in medusa body plan - eggs and sperm released into seawater to form zygote which developes into a planula

Name the three ways a Cnidarian can use cnidocytes.

1. Penetrants - penetrates tissue of prey allowing neurotoxin to go into prey to paralize 2. Volvents - long thread that tangles prey 3. Glutinants - sticky proteins that attach prey to nematocyst thread.

List 5 identifying features of members of the Phylum Cnidaria.

1.most have cnidocytes 2.radial symmetry is dominant but planula larva has bilateral symmetry 3. two true tissue layers - diploblastic 4. many possess "alternation of generations"

Which of the following is an example of a truly colonial medusoid cnidarian composed of different types of polyps? A) Physalia (Portuguese man-of-war) B) Obelia C) Hydra D) Aurelia E) All of the above are correct

A) Physalia (Portuguese man-of-war)

Which of the following is a highly toxic cubozoan? A) The cubomedusa, Chironex fleckeri B) Hydra C) Aurelia D) Physalia E) None of the above is correct

A) The cubomedusa, Chironex fleckeri

Although members of the phylum Cnidaria are more highly organized than sponges, they are still relatively simple animals. However, many cnidarians are very effective predators that are able to kill and eat prey that are much more highly organized, swift, and intelligent than they are. A) True B) False

A) True

Coral reefs are some of the most productive of all ecosystems, and they have a diversity of life forms rivaled only by the tropical rain forests. Of all earth's reefs, the Great Barrier Reef of Australia is the longest and the most diverse in terms of numbers of species. A) True B) False

A) True

Heavy branching corals typically live near the reef crest A) True B) False

A) True

In the life cycle of Obelia, they bud from a reproductive polyp called a gonangium. A) True B) False

A) True

Members of the Phylum Ctenophora take their name from the eight rows of comblike plates they use for locomotion. A) True B) False

A) True

The barb of a cnidocyte may explode at an acceleration greater than 40,000 times the pull of gravity. A) True B) False

A) True

The life cycle of Aurelia, a scyphozoan, could be described as follows: ciliated planula larva, scyphistoma, strobila, ephyra larva, medusa, sexual reproduction and zygote, ciliated planula larva. A) True B) False

A) True

There are two basic types or forms in some groups of cnidarians. These two basic forms are called the medusa and the polyp. A) True B) False

A) True

Which of the following is incorrect? A) The siphonoglyph is a ciliated groove that extends into the pharynx of a sea anemone. B) Anemones form some interesting mutualistic relationships with bacteria within their tissues. C) Sexes are separate in some sea anemones whereas others are hermaphroditic. D) Asexual reproduction may occur by pedal laceration. E) Octocorallian corals have strict octomerous symmetry.

B) Anemones form some interesting mutualistic relationships with bacteria within their tissues.

The Phylum Cnidaria takes its name from special cells called ____________. that contain stinging organelles called ______________. A) Cnidoblasts, nematodermic needles B) Cnidocytes, nematocysts C) Flagella, cilia D) Colloblasts, ciliary combs E) None of the above is correct

B) Cnidocytes, nematocysts

A jellyfish that has a pedalium on the tentacle and a velarium on the umbrella margin is in the class A) Anthozoa B) Cubozoa C) Staurozoa D) Hydrozoa E) Schyphozoa

B) Cubozoa

Although the origin of cnidarians and ctenophores is obscure, the most widely supported hypothesis today is that radiate phyla arose from a bi-symmetrical, planula-like ancestor. A) True B) False

B) False

Ctenophores undergo a drastic metamorphosis before becoming an adult A) True B) False

B) False

Hox genes are highly diverse throughout almost all Metazoa and control expression of other genes determining body axis and morphogenesis along the body axis. A) True B) False

B) False

The Anthozoa, or "flower animals," are polyps with a flowerlike appearance. All species are characterized by a free-swimming medusoid form. A) True B) False

B) False

The radiate phyla are characterized by the tissue level of organization, with an internal gastrovascular cavity, extracellular digestion, and a complete digestive tract (mouth-to-anus). A) True B) False -

B) False

The rhopalium of Aurelia is a reproductive organ containing a hollow statocyst for equilibrium and one or two pits lined with sensory epithelium. A) True B) False

B) False

The two phyla Cnidaria and Ctenophora make up the radiate animals, which are characterized by primary radial or biradial symmetry, but evolved from an ancestor characterized by radial symmetry. A) True B) False

B) False

There are no freshwater medusoid cnidarians (cnidarians with a medusa). A) True B) False

B) False

Lying between the epidermis and gastrodermis of hydra is a gelantinous or jellylike middle layer called the? A) Mesohyl B) Mesogloea C) Mesenchyme D) Mesoderm E) None of the above is correct

B) Mesogloea

Interstitial cells are characterized by? A) Secreting an adhesive substance for attachment B) Being undifferentiated stem cells C) Being multipolar D) Serving both as a covering and for muscular contraction E) None of the above is correct

C) Being multipolar

Which of the following widened the ecological possibilities available to the cnidarians? A) Nematocysts B) Ciliary comb plates C) Polymorphism D) Radial symmetry E) None of the above is correct

C) Polymorphism

The scyphistoma of Aurelia forms a series of saucerlike buds called ephyrae by the process of ? A) Pedal laceration B) Sexual reproduction C) Strobilation D) Pedalation E) None of the above is correct

C) Strobilation

Which Cnidarian Class displays the simplist form of parental care when the female protects her fertilezed eggs during development on her oral arms.

Class Scyphozoa

A Cnidarian's cell that contains a nematocyst. A stinging cell.

Cnidocyte

Name the tiny obligate freshwater medusae Hydrozoa that lives in Oklahoma lakes.

Craspedacusta

Radiates are the simplest animals to possess sense organs, include which of the following? A) Statocysts B) Ocelli C) Compound eyes D) A and B, but not C E) None of the above is correct

D) A and B, but not C

Which of the following is not a characteristic of phylum Ctenophora A) Biradial symmetry B) Colloblasts C) Anal pore D) Coelomic cavity E) Muscle cells

D) Coelomic cavity

The combination of sensory-nerve cell net and epitheliomuscular cells common in most cnidarians is often called a primitive? A) Gastrovascular system B) Osmoregulatory system C) Reproductive system D) Neuromuscular system E) None of the above is correct

D) Neuromuscular system

Which of the following is mismatched? A) Statocysts-small organs of equilibrium B) Ocelli-light-sensitive organs C) Craspedacusta-freshwater medusa D) Pneumatophore-primitive lungs E) Dactylozooids-long, stinging tentacles

D) Pneumatophore-primitive lungs

Ctenophores resemble cnidarians in all but one of the following ways: A) Form of radial symmetry B) Well developed gelatinous ectomesoderm (Collenchyme) C) No coelomic cavity D) Presence of comb plates and colloblasts E) Lack of organ systems -

D) Presence of comb plates and colloblasts

Which of the following is NOT a form of reef? A) Fringing reef B) Barrier reef C) Patch or bank reefs D) Segmental reefs E) All of the above are examples of reef forms

D) Segmental reefs

Which of the following would be characteristic of the sea anemone, Metridium? A) Acontia threads B) Pedal disc C) Septa D) Tentacles E) All of the above are characteristics of Metridium

E) All of the above are characteristics of Metridium

The sea anemone may reproduce by which of the following methods? A) Pedal laceration B) Longitudinal fission C) Budding D) Sexual reproduction E) All of the above are correct

E) All of the above are correct

The free-swimming larval stage of a ctenophore is called A) Gemmule B) Parenchymula C) Amphiblastula D) Planula E) Cydippid

E) Cydippid

Which of the following is NOT matched correctly? A) Hypostome-where a hydra's mouth is found B) Nerve cells-multipolar nerves found in the epidermis C) Colonial polyps-can drift across the ocean using floats D) Hydra-solitary polyps found in fresh water E) Hydranths-reproductive polyps

E) Hydranths-reproductive polyps

This is the motile Cnidarian body form. Looks like pulsating open umbrella. Mouth faces down.

Medusa

Where are most of the cnidocytes found on a Cnidarian?

Most are found on the tentacles not on the bell.

Is the Portuguese man-o-war considered to be a jellyfish?

No

Describe the integumentary system in a Cnidarian.

One cell thick - epidermis

Which way(s) does a Cnidarian use cnidocytes to obtain larger prey like fish?

Penetrants

A tiny free-swimming bilaterally symmetrical cilia covered cnidarian larva.

Planula

This is the sessile Cnidarian body form. Looks like a tree with the branches as tentacles. Mouth faces up.

Polyp

Name the two Cnidarian body plans

Polyp & Medusa

Name the Hydrozoan colonial polyp that uses it's pneumatophore to float and catch wind to move.

Portuguese man-o-war.

This Anthozoan has some of the oldest animal fossiles on earth. Has been around for 600 million years.

Sea Pen

All Cnidarian Anthozoans have a GVC divided into these walles areas.

Septae

The Portuguese man-o-war is a member of which Order?

Siphonophora - deep water colonial polyps

Name and describe the two types of cells found in the rhopalium of the Cnidarian Class Scyphozoa.

Statocysts - sense gravity with floating crystals in the cell that land "down" ocelli - light sensors, swim slower with more light to stay in the photic zone

What is the pedalium in Cnidarian Cubozoans and what is is used for?

The Cubozoans have a pedalium at the base of each tentacle. Tentacles extend from the pedalium in groups of four. used for swimming and capturing prey.

Explain the function of the gastric pouches in Cnidarian Scyphozoans.

The gastric pouch functions as circulatory parts and contains radial canals and a ring canal.

Which way(s) does a Cnidarian use cnidocytes to obtain planktonic food?

Volvents and Glutinants

Are cnidarians monoecious or dioecious?

Yes, Corals & Polyps are monoecious Medusa are dioecious

Name a form of asexual reproduction seen in most polyp body plans.

budding

A stinging cell

cnidocyte

The Cnidaria are characterized by which of the following? A) Primary radial symmetry B) Tissue level of organization C) At least two well

defined germ layers D) True nerve cells that form a primitive "nerve net" E) All of the above are correct - E) All of the above are correct

Describe the Cnidarian muscle system.

epitheliomuscular cells can contract in one direction.

Describe the Cnidarian excretory system.

most are isotonic (no osmosis) NO ORGANS

Is fertilization in Cnidarian sexual reproduction external or internal?

most is external fertilization as in corals syphrazoan jellyfish use internal fertilization

Stinging organelles within a cnidocyte

nematocysts

Describe the Cnidarian respiratory system.

none - gasses diffuse as in sponges

Describe the Cnidarian circulatory system.

none, but substances are shared among cells of epidermis and gastrodermis via gap junctions. ** GVC and its branchess (radial canals) circulate nutrients

Tiny life forms drifting in ocean currents, food for Cnidarians.

plankton, zoplankton

Members of the Cnidarian Class Scyphozoa have this cluster of sensory cells around the margin of the bell.

rhopalium