Zoology Test 3 review

Asexual Reproduction in Hydras

-Asexual reproduction, buds appear as outpocketings of the body wall and develop into young hydras that eventually detach from the parent. -

Explain the difference between dimorphism and polymorphism. Which of these is more common in the Cnidarians?

-Dimorphism: (2 body forms) a polyp, or hydroid form, which has a sedentary or sessile lifestyle, and a medusa, or jellyfish form, which has a floating or free-swimming existence. -Polymorphism: (multiple body forms) Medusae are usually free-swimming and have bell-shaped or umbrella-shaped bodies and tetramerous symmetry (body parts arranged in fours). -Dimorphism

How do the freshwater hydrozoans differ from the marine hydrozoans?

-Fresh water: solitary, polyp, does not form colonies. Two common forms- chlorohydra viridissima, plematohydra oligactis. -Marine: colonial, dimorphic-medusa and polyp stages

Describe the four different types of movements found in the hydra.

-Handspring: head over tail -Measuring worm movement: looping along a surface by bending over & attaching their tentacles to the substratum. -Basic disc gliding: secrete mucus at base to slide -Gas bubble: trap air gas in disc, release, float

Structure and function of jellyfish Aurelia

-Lappets: rhopalium, lobelike projections on side of ephyra jelly, multi oral arms, can capture -Sensory structures Oral arms: where eggs develop Gastric pouches with gonads and gastric filaments Manubrium: mouth Gastrovascular cavity: hydrostatic skeleton

Is the nerve net the same as the central nervous system? Explain.

-No -no concentrated grouping of nerve cells -nerves are grouped in the "ring nerves" of hydrozoan medusae and in the marginal sense organs of scyphozoan medusae.

Most cells in the epidermis of a hydra have what shape? Describe the different types of cells found in the epidermis of the hydra.

-cube shaped -Sensory cells, Nerve Cells, Interstitial Cells, Cnidocytes, Gland Cells

What is the main function of the hydranth? What is another name for the hydranth? What is the function of the gonangium?

-hydranth - capture and ingest prey, mouth - feeding polyp -Gonangium - strictly asexual reproductive polyps

Where is the nerve net located in the cnidarians? How is this nerve net or plexus similar and different from our nerve network?

-located at base of ectoderm and endoderm _______________________ -had bidirectional -neurotransmitters -lack myelin -no central nervous system -has neuromuscular system

What are the most common foods of the hydra? How is the digestion in the hydra more advanced over the other organisms we have discusses in the past? How is the digestion in the hydra similar to the other organisms we have discussed in the past? Which of the cells found in the gastrodermis of the hydra complete digestion?

-small crustaceans, water fleas, aquatic worms, insect larva -Extracellular digestion - secrete digestive enzyme, break it down, finish with intracellular digestion -The presence of a gastrodermis and because extra and intracellular digestion occurs; others feed by use of canal systems or pseudopodia. -Digestion is similar because they all engulf nutrition -Cell in gastrodermis - nutritive muscular

Life Cycle of Aurelia

1)Medusa 2)Zygote(develops on arms of female) 3)Ciliated planula larva 4)Planula settles 5)Scyphistoma 6)Early Strobila 7) Strobila 8)Ephyra 9) Back to Medusa Stage

List six characteristics of the radiate animals.

1. Ectoderm, Endoderm and Mesoglea (Diploblastic) 2. Sac-like body plan (gastrovascular cavity) 3. True tissue, true nerve cells, true sensory cells 4. May be monomorphic, dimorphic or polymorphic 5. presence of cnidocytes 6. some have colloblast

When was the Phylum Cycliophora first described? Where do you find the cycliophorans and how many species are there?

1995 by Funch & Kristensen Live on the mouthparts of some lobsters Small phyla—only 3 species have been discovered

Briefly describe the structure of a polyp. Briefly describe the structure of a medusa.

>Polyp- Attaches Tubular body Mouth upward Feeding Reproduce asexually Mostly sessile Somersaulting, inchworm, glide, walk >Medusa- Bell or umbrella shaped Mouth downward Tentacles directed down Motile, but weak Horizontal vs vertical Reproduce sexually

Sensory Cells

Among other Epi. cells. Especially around the mouth and tentacles. The free end of each sensory cell bears a flagellum, which is the sensory receptor for chemical and tactile stimuli. The other end branches into fine processes, which synapse with nerve cells.

Which class of cnidarians is also called flower animals? What are the general characteristics of this class?

Class Anthozoa - flower animals No medusa stage - monomorphic All are marine Gastrovascular cavity divided into chambers by septa or mesenteries

To which Class do the true jellyfish belong?

Class Schyphozoa

Explain the difference between the two different classes found in the phylum Ctenophora.

Class Tentaculata - has tentacles Class Nuda - lacks tentacles

Cnidocytes

Cnidocytes- Cnidocytes (containing cnidae) occur throughout the epidermis (see figure 7.4 right). They may be between the epitheliomuscular cells or housed in invaginations of these cells, and they are most abundant on the tentacles.

Explain why your textbook says that although the polyp and medusa seem different they are actually very similar.

Each retained the saclike body plan basic to the phylum A medusa is essentially an unattached polyp with the tubular portion widened and flattened into the bell shape. Both possess two tissue layers with an extracellular matrix (ECM) called mesoglea between them, but the jellylike layer of mesoglea is much thicker in a medusa. Making them Jellies.

Epitheliomuscular

Epitheliomuscular- form most of the epidermis and serve both for covering and for muscular contraction.protective covering, contacting, locomotion, attachment, respiration

What are the general characteristics of the Clade Lophotrochozoa and the Clade Polyzoa? Which phyla belong to the Clade Polyzoa?

Group of animals that often have a U-shaped gut, many are colonial, and may have tentacles Cycliophora, Entoprocta, and Ectoprocta

How does the mesoglea of the hydra differ from the mesoglea of the sponges?

Hydra mesoglea lies between epidermis and gastrodermis Gel like Lacks fibers and cellular elements in hydrozoan polyp Thicker medusa Has elastic fibers Sponge medusa has ameboid cells Hydra medusa has epitheliomuscular cells

Be able to identify the following structures on the hydroid colony of an Obelia; hydrorhiza, hydrocauli, coenosarc, perisarc, hydranth, hydratheca and gonangium.

Hydrothiza - water root; anchors root/colony to rock Hydrocauli - branches Coensarc - living tissue that interconnects all members of a colony Perisarc - out covering chitenoeus; clear Hydranth - feeding polyp Hydrotheca - perisarc enclosing hydranth forming supporting cup Gongangium - reproductive polyp

interstitial cells

Interstitial- undifferentiated stem cells among bases of epitheliomuscular cells. Differentiation of interstitial cells produces cnidoblasts, sex cells, buds, nerve cells, and others, but generally not epitheliomuscular cells (which reproduce themselves).

What is unique about Turritopsis dohrnii lifecycle? Explain how this works?

Jelly can turn lifecycle into reverse and becomes a cyst and produces polyp cells and asexually polyp release copies of itself. Transdifferentiation: when mature cells that have already been assigned a function become different kinds of cells.

In what type of habitat do you find most cnidarians?

Most are marine, some freshwater.

Describe some of the symbiotic relationships of the sea anemone.

Mutualism - algae; algae is safe and anemone is nourished Commensalism - clownfish, hermit crab

Class Myxozoa are what type of parasites? What is unique about them? Why should we care?

Obligate parasites

What is unique about the genus Gonionemus?

Only genus that has adhesive disk on tentacles to help locomote Because of loco: theory they develop extra tentacles

To which order and genus does the Portuguese man-of-war belong? Be able to identify and describe the function of the following structures found in the Portuguese man-of-war; pneumatophore, gastrozoid, dactylozooids and gonophores.

Order - Siphonophora Genus - Pysalia Gastrozooid - digestion polyp; mouth Dactylzooid - fishing polyp; capture fish

What is the function of the statocyst?

Organs of balance AKA tells if the organism is right side up or upside down

Which of the dimorphic forms is considered a persistent larval or juvenile stage? Which of the dimorphic forms is considered a complete and typical cnidarian?

Polyp-juvenile stage Medusa-complete stage

What is the most characteristic feature of the cnidarians? Do any other group of organisms have these feature? If so, which ones?

Presence of cnidocytes (stinging cells) Yes Phylum ctenophora

What type of symmetry do the Cnidarians and Ctenophorans have? How is this type of symmetry an advantage for these organisms?

Radial can move in any direction, if it loses a limb, one can grow back

Gland Cells

Secrete digestive enzymes Gland cells are particularly abundant around the mouth and in the pedal disc of hydra. They secrete mucus or adhesive material.

Sexual Reproduction in Hydras Why it is more common in winter?

Sexual reproduction, temporary gonads appear in autumn, stimulated by lower temperatures and perhaps also by reduced aeration of stagnant waters. Testes or ovaries, when present, appear as rounded projections on the surface of the body. Eggs in the ovary usually mature one at a time and are fertilized by sperm shed into the water. -A cyst forms around the embryo before it breaks loose from the parent, enabling it to survive the winter. Young hydras hatch in spring when the weather is favorable.

Describe or diagram (labeling all of the parts) a cnidocyte.

Structure of Cnidocytes: Cnidocil, Operculum, Nematocyst, Filament and Barbs

Nutritive-Muscular Cells (Gastrodermis)

Tall columnar cells that have laterally extended bases containing myofibrils. Longitudinal extension of the body and tentacles occurs mostly by increasing the volume of water in the gastrovascular cavity.

What make scyphozoan medusae different from hydrozoans?

The medusae of scyphozoans, unlike those of hydrozoans, have no velum.

What are the general characteristics of the mesoglea of the common jellyfish?

The mesoglea contains amoeboid cells known as collenchyme

Describe the general features of the Phylum Entoprocta. By what means do the entoprocts acquire food? How many species belong to his phylum? Define "protandric".

The phylum name for this group means "within anus". Small phylum-150 species Do not look like any other pseudocoelomate. Are filter feeders All marine except for one genus (Urnatella) which is freshwater. Monoecious, dioecious and protandric Trochophore-like larva

Briefly describe what occurs when a cnidocyte is triggered. How can they be triggered?

When a cnidocyte is triggered it fires a stinging cell called a nematocyst. When stimulated to discharge the permeability of the nematocyst changes and the internal osmotic pressure causes water to rush into the capsule. The operculum opens and rapidily increasing hydrostatic pressure within the capsule force the thread outward, the thread turning inside out as it goes. The barbs of the nematocyst injects venom when the prey is penetrated. -Tactile stimulation causes a nematocyst to discharge. When a nematocyst has discharged, its cnidocyte is absorbed and a new one replaces it. Also chemicals and touch activate trigger

Explain what is meant by "pseudocoel". What are the advantages of the pseudocoel?

a body cavity (as in various worms) that is not the product of gastrulation and is not lined with a well-defined mesodermal membrane. Greater freedom of movement Space for development & differentiation of organ systems Storage area for waste Hydrostatic skeleton

Know the similarities and differences between the Ctenophorans and Cnidarians.

both are biradial Cnidaria - phylum, diploblastic, medusa and polyp form Ctenophorans - no colonies, only marine, comb rows, only medusa form

What are the two more common types of hydra found in the U.S.? Where could you find these hydra?

chlorohydra and plematohydra fresh water - clean freshwater pools, streams, aquatic leaves, underside of lily pads

What is the main difference between the two classes found in the Phylum Brachiopoda?

class articulata- Made from calcium Carbonate with tooth and socket hinge class inarticulata-- Usually made from calcium phosphate without articulating hinges.

Explain the relationship between a cnidocyte and a nematocyst.

cnidocyte is the trigger that releases the nematocyst (the stinging cells)

Most cells in the dermis of a hydra have what shape? Describe the three different types of cells found in the dermis of the hydra.

column shaped Nutritive muscular cells Gland Cells Interstitial Cells

What is one of the most productive ecosystems on this earth? Which two organisms mainly compose this ecosystem?

coral reefs hermatypic corals and coralline algae

How does the phylum Ectoprocta differ from the Entoprocta? What other name are the ectoporcts often called? What are the general characteristics of the Phylum Ectoprocta?

ectoprocta is freshwater Aquatic colonial organisms that often attach to some substrate Most are sessile Ciliated crown of tentacles (common to all lophotrochozoans) Zooids are small and usually microscopic (each zooid lives in a chamber called a zoecium AKA Bryozoans

Nerve Cells

fast cell communication, sends impulses through nervous system

Physalia Polyp Types

feeding polyps, reproductive polyps, long stinging tentacles, and so-called jelly polyps. Gastrozooids: digestion Dactylozooids: locating and catching prey (tentacles) Gonozooids: reproduction Pneumatophore: float, ability to move prey up to mouth with tentacles.

Describe the four different types of coral reefs.

fringing - comes up to land, grows near coast line around islands and continents barrier - parallel to the coastline and separated by deep wide lagoons, at their shallowest point they become a barrier to navigation Atoll - formed where once was an island, form when an island surrounded by fringing reefs sink or sea level goes above land patch - vary in size, rarely reach surface of water, grow up from bottom of ocean

Describe the comb plates. What is the function of the comb plates?

fused cilia that function in locomotion

The Phylum Brachiopoda resembles what other group of animals? How are they different from this "other" group of animals?

mollusk different in that the shells are not equal in size

How is the nemertine worms more advanced in comparison to the flatworms?

more highly developed circulatory and respiratory system

What are the general characteristics of the Class Cubozoa? Which of the cubozoan jellyfish is considered to be of extreme importance and why?

most are dimorphic but polyp is small and barely noticeable medusa is cube shaped and small base of each tentacle is flat AKA pedalium Chironex Fleckeri (sea wasp) - most lethal and small. Can die after getting stung within 20 minutes

Gastrodermis cells

nutritive-muscular, interstitial, and gland cells and, in classes other than Hydrozoa, cnidocytes. (Gonads are gastrodermal in most cnidarians.)

What is another name for the mesoglea within the anthozoans?

parenchyma

Which does your textbook came first the polyp or the medusa and why?

polyp

What is another name for the Phylum Nemertea? What are the general characteristics of the Nemertine worms?

ribbon worms or Rhynchocoela Have a long retractable proboscis; complete digestive system; & circulatory system Most are marine Approximately 650 species Range from 20cm to over 30 meters Usually brightly colored

Give the general characteristics of the Phylum Ctenophora.

small, planktonic, medusa like body, comb rows, no polymorphism, no colonies, biradial symmetry, digestion as food passes through pharynx, gastrocavity, and canals

Why does your text believe that the cnidarians and ctenophorans may not have a shared ancestry with bilateral animals? How does your text explain some of shared characteristics between these two groups?

they may have come about independently

List the three different subclasses of the "flower animals". What are the main differences between these subclasses?

• Zoantharia- o Hexacorallia= septa arranged in multiples of six (hexamerous) o Stony or true corals. o Exoskeleton- Sclerosepta secreted below the living tissue. o May be solitary or colonial • Ceriantipatharia- o Tube, anenomes. Thorny corals. o Also hexamerous (body plan multiple of 6). o Solitary. No colonies. o Warm water, Black Coral. • Alcyonaria- o Octocorallia- body plan in multiples of 8 (octomerous). o Soft or horny corals. o All are colonial. Salt water. o Contain solenia which are tubes of gastrovascular cavity that intercommunicate between individuals of a colony o Endoskeleton

Explain, in detail, the difference between Zoantharian and Alcyonarian corals. Give an example for each of these types of corals.

• Zoantharian- Sea anemone. True coral. Multiples of 6. Exoskeleton. It is solitary, colonial. • Zoantharian- Sea anemone. True coral. Multiples of 6. Exoskeleton. It is solitary, colonial.