ZOOL Lab 3 Cnidaria And Ctenophora

Hypostome (Hydra)

The mouth is located on a cone-shaped manubrium. This entire structure is called ___________.

Basal Disk (Hydra)

"Foot", attaches to substrate

How does the skeleton of a gorgonian coral differ from a stony coral?

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How many corallites are present in each skeleton?

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Life cycle of Scyphozoan (Aurelia) (draw)

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Life cycle of a Hydrozoan

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Mesoglea (Aurelia)

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Metridium (draw)

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Obelia (draw)

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3-layered tissue in Hydra (draw)

Epithelio-muscular cells mesoglea gastrodermis cnidocytes epidermis

Hydra: Eggs, testes, and buds

From Ectoderm

Order limnomedusae

Gonionemus: trachyline medusa...

Order anthomedusae

Hydra: an athecate hydroid, an atypical freshwater form

velum (gonionemus)

Jet propulsion

Scyphozoan: What causes the bell to expand after a swimming contraction?

Mesoglea encourages the siwmming bell to return to its initial shape between nerve pulses.

Order actiniaria

Metridium: multitentaculate marine anenome Anthopleura:

Order milleporina

Millepora: fire coral, hyrocoral...

How does a nematocyst differ from a cnidocyte

Nematocyst is the organelle inside the cnidocyte

Order leptomedusae

Obelia: a thecate hydroid...

Class Scyphozoa

Polyp stage reduced

Thecate hydroid

Polyps are protected by a thecate holster.

Millepora; coral-like Hydrocoral. Size of corallites differ how compared to true coral?

Radial corallites are closely compacted and all the same size."

Medusae produced by:

Simple budding in Hydrozoa and strobilation in Scyphozoa.

Are the corallites of different species of the same shape? (Favia, Manicina, Fungia)

corallites can be quite variable in shape and form, even within the same corallum .

Tentacles (gonionemus)

food capture (not propulsion?)

Gonozooid

reproductive

Radial Canals (gonionemus)

"Vascular system" Moves nutrient throughout organism.

Corallites

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Athecate hydroid

These hydroids always have a polyp stage during their life-cycle. The polyps of Athecate hydroids are not protected by a holster, in contrast to the polyps of the Thecate hydroids. (doesn't that mean that the hydra does not posses an exoskeleton because the theca, made of chitin is the exoskeleton?)

Order semaeostomeae

Aurelia: a small marine 'true' Jellyfish...

How are Ctenophores different from Cnidarians?

Ctenophores posess 8 'comb rows' of complex cilia for locomotion and two long branched tentacles, where the branches are covered with sticky colloblast cells. cnidocytes are absent and are biradially symmetrical.

Skeleton of a Hydra

Exoskeleton (? even in athecate?) and Hydroskeleton.

Porites

Finger coral. Order Scleractinia. Class Anthozoa

Tentacles (Hydra)

Food capture

Tentacles (Metridium)

Hollow, eating

Do Hydra posess an anus?

No

How far down the Pharynx do the siphonoglyphs extend? (Metridium)

Running two-thirds length

Gastrovascular cavity (Metridium)

Both for digestion and for the dissipation of nutrients throughout the body.

Hydrocoral

Have a calcareous skeleton resembling that of the true corals. They differ from stony corals in having a smooth surface and tiny pores with thin hairs that deliver painful stings.

Physalia, how is it different than typical siphonophores?

It is not colonial, it is without swimming bells, it is smaller, specialized polyps,tentacles and medusae used to catch fish. and especially long nematocysts.

Class Anthozoa

Medusa stage absent

Cnidarian symmetry

Radially symmetry

Order scleractinia

Stony corals: Fungia, Porites, Favia, Acropera, Oculina

Acropera

Straghorn coral, one of the various stony corals. Order Scleractinia. Hexacoral. Class Anthozoa.

Siphonoglyphs (Metridium)

The siphonoglyph is a ciliated groove at one or both ends of the mouth of sea anemones and some corals. The siphonoglyph extends into a pharynx and is used to create currents of water into the pharynx. These water currents are important for respiration and maintenance of internal pressure.

True Coral Corallites

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What is a true coral?

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Class Hydrozoa

Both Polyp and Medusa

Nerve cells in Cnidaria function to:

Coordination and communication (?)

Mouth Lobe (Aurelia)

End of the short manubrium there are mouth lobes. These have ciliated grooves with nematocysts. These paralyze prey and secret mucus moving the food up the ciliated grooves to mouth. Nematocysts are concentrated here.

Manubrium (gonionemus)

Extension of mouth, feeding tube. Join exterior to gastric cavity (mouth is at end) Simple manubrium

Which parts of a Siphonophore are modified medusae?

Have swimming bells/ nectophores: only serve to propel the colony, can't feed or reproduce.

2 groups within class anthozoa

Hexacorals, Octocorals

Which classes show an alternation of generations

Hydrozoa and Scyphozoa

Mesoglea importance:

Most important in medusae because it is a supportive skeleton and a muscle agonist while swimming.

Fungia

Mushroom coral, Order Scleractinia. Class Anthozoa.

Order in Scyphozoa

Order semaeostomeae

Medusae: Hermaphroditic or do they have separate sexes?

Separate Sexes

How does the larval medusa (ephyra ) form differ from the adult form?

Size

Pedal Disc (Metridium)

Smooth muscular mucusc-coated and the anemone can creep about and holds to rocks.

Nematocysts

Stinging organelle in Cnidocytes. Concentrated in the epidermis of tentacles but also occur in the tissues lining the gut,

What makes up the exoskeleton of a Hydra? (thought Hydra were athecate?)

Theca -> Chitin

Gastrozooid

feeding

How are Ctenophores like Cnidarians?

resemble cnidarian medusae. Gelatinous, diploblastic with an extensive mesoglea-like middle layer, and radiating gastrovascular canal system.

Does the planula larva have a distinct head end?

yes, found through Hox gene investigation

Aurelia (draw)

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How many radial canals are there in a Gonionemus?

4

2 orders within hexacorals

Actiniaria, Scleractinia...

5 orders within class Hydrozoa

Anthomedusae Leptomedusae Siphonophora Limnomedusae Milleporina

How do the radiating canals of Aurelia differ from those of Gonionemus?

Aurelia is a representative of Scyphozoa which as branching canals while Gonionemus as a representative of Hydrozoa which is a simple canal.

How does the manubrium of Aurelia differ from that of Gonionemus?

Aurelia: Notched bell Gonionemus: Simple bell

Colloblast cells

"Colloblasts are a cell type found in ctenophores. They are widespread in the tentacles of these animals and are used to capture prey. Colloblasts consist of a coiled spiral filament that is embedded in the epidermis and an axial filament with a granular dome.[1] The apical surface of these cells consist of eosinophilic granules that are thought to be the source of adhesion.[2] On contact, these granules rupture, and release an adhesive substance onto the prey. The spiral filament absorbs the impact of the rupture preventing the ensnared prey from escaping." (wikipedia)

Ctenophora (pleurobrachia) - # tentacles - How do they attach to body? - By what mechanism do tentacles capture prey? - Is the mouth located on a manubrium? - Is the gastrovascular cavity simple or branched? - what is an individual comb and how do they function? - What are the main differences between a ctenophore and hydromedusa?

-2 tentacles -Tentacle sheaths, deep ectoderm-lined pouches that indent the mesoglea. -Raptorial capture: have colloblasts instead of nematocysts, these are adhesive and used to ensnare prey. - Gastrovascular cavity with radiating canals. -Ctene row -lack cnidocytes

Contracted Anemone: how can they reduce their size so dramatically? What role does the gastrovascular cavity play, if any, as part of an anemone skeleton.?

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Do ctenophores have nematocysts?

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How are prey transferred to the mouth by Aurelia?

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How does the mesoglea differ between Hydra and Gonionemus, both of which are hydrozoans?

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Ptilosarcus (draw)

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Scyphozoan (draw)

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Siphonophore

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Where are prey captured by Aurelia?

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Anemones: How is food captured? Transported to the mouth? Is the entire body covered in nematocysts?

1) filter feeding, where small organic particles, both live and dead, are removed from the seawater passing over the outspread tentacles, 2) raptorial capture, where zooplankters and motile benthic prey are caught by the tentacles, and 3) passive capture, where sessile prey are dislodged by foraging predators or wave action and carried onto the tentacles. Any plant matter ingested occurs by this means.

How many different kinds of polyps are there? (Ptilosarcus) What are their functions?

2 or 4: Autozooids and Siphonozooids. The Siphonozooids can be split into 2 categories: Excurrent and Incurrent. Autozooids are feeding polyps Siphonozooids are used for the movement of water.

How many calcareous septa are in an individual corallite?

8, because calcareous septa are in Octocorallia.

Octocorals

All polyps with 8 pinnate tentacles, and 8 septa

Which are more closely related to each other among the following groups and why: Anemone, Stony Coral, Gorgonian, Sea Pen?

Anemone and Stony coral are most closely related because they are both in Hexacorals. Gorgonian and Sea Pen are most closely related because they are both Octocorals.

Epithelio-muscular cells

Basal muscle processes running parallel to each other. Below nerve net and epidermis. This creates the longitudinal muscles. Bends in the direction of greatest contraction.

Favia

Brain coral, Order Scleractinia. Class Anthozoa.

Radial Canals (Aurelia)

Branched.

Strobilation

Budding off medusas by successive constrictions.

Comb-rows (Ctenophore)

Cilia, the most aboreal comb beats first, the others successively along the row, Since some will be falling while others are rising.

Gastrodermis

Digestion, flagellated cells (Are cnidocytes found here?)

Tissue organization in Cnidarians

Diploblastic, epidermis and gastrodermis. They have a basal lamina. Mesoglea is middle layer and is non cellular.

Oculina

Eye coral, order scleractinia in Class Anthozoa.

What are the most conspicuous differences between Gastrozooid and Gonozooid?

Gastrozooid has tentacles and a smaller body. Gonozooid has no tentacles and a thicker body.

What are the two major anatomical differences between a hydrozoan polyp and an anthozoan polyp?

Gonads are epidermal in Hydrozoa and gastrodermal in Anthozoa. Tentacles are solid in Hydrozoa and hollow in Anthozoa. mouth and pharynx = simple in Hydrozoa and tubular + Siphonoglyph in Anthozoa.

3 orders within octocorals

Gorgonacea, Pennatulacea, Stolonifera...

Order gorgonacea

Gorgonia: Gorgonian sea fan Corallium: sim. to be sea whip both are 'soft corals'

Gorgonian

Gorgonians are also known as sea whips or sea fans and are similar to the sea pen, a soft coral. Gorgonians are closely related to, but technically not coral, themselves. Individual tiny polyps form colonies that are normally erect, flattened, branching, and reminiscent of a fan. Others may be whiplike, bushy, or even encrusting.

Cnidarian skeleton

Hydrostatic, many secrete rigid or semi rigid skeleton. External in some (coral) and internal in others (gorgonians).

Colonial forms with a division of labour have evolved in 2 Cnidaria classes:

Hydrozoa and Anthozoa

3 classes of phylum Cnidaria

Hydrozoa, Scyphozoa, Anthozoa

Polyp forms of each class differ:

Hydrozoa: mouth is simple opening, simple gastrovascular cavity, nematocysts absent in gastrodermis. Scyphozoa: mouth is simple opening, septate gastrovascular cavity, nemetocysts present in gastrodermis. Anthozoa: mouth opens into pharynx that is ciliatied (siphonoglyphs), septate gastrovascular cavity, nematocysts present in gastrodermis.

Medusae differ between Hydrozoa and Scyphozoa :

Hydrozoa: small, velum present, Simple bell margin, small simple manubrium, lacking nematocysts, arise by budding, simple canals, gonads arise epidermally, Scyphozoa: large, velum absent, notched bell margin, large elaborate mouth lobes from manubrium with nematocysts, arise via strobilation, branched radial canals, gonads arise gastrodermally.

Pharynx (Metridium)

Incurrent canal water and food is drawn into.

Septa (Metridium)

Internal layer of the wall, The gonads are attached at the lower parts of the wall.Vertical partitions that connects the gastrovascular cavity to the wall. Two sheets of endoderm with mesoglea between.

Gastric pouches (Aurelia)

Nematocysts inside with gastric filaments for digestion.

Nerves in Scyphozoa vs. Hydrozoa

Nerves in the medusae or Scphozoa are concentrated in marginal nerve centers called Rhopalia while Hydrozoa nerves are marginal nerve rings around the edge of the swimming bell.

Does the pharynx extend all the way to the pedal disc? (Metridium)

No

Sea pen

Order Pennatulacea = Sea pens are grouped with the octocorals ("soft corals"), together with sea whips and gorgonians.

Rhopalia (Aurelia)

Orientation, knowing straight or tilt and sensory

Epidermis

Outside layer, protection

Order siphonophora

Physalia: Portuguese man of war, an exotic colonial siphonophore...

Scyphistoma

Polyp form. After settling to the sea floor, the planula larva attaches itself to a hard surface and transforms into a polyp (or scyphistoma). This polyp stage in the jellyfish life cycle is a sessile stage, so called because the polyp is stationary and remains attached to a single spot on the sea floor. A polyp is cylindrical and stalk-like in form. At its base is a disc that adheres to the substrate and its top is a mouth opening surrounded by small tentacles. The polyp feeds by drawing food into its mouth. It grows and begins to bud new polyps from its trunk. As it does, the polyp develops into what is called a polyp hydroid colony (or strobilating scyphistomata). Members of the polyp colony are linked together by feeding tubes. The entire polyp hydroid colony, like the originating polyp, is sessile. The polyp colony can grow for several years. When polyps within the colony reach an adequate size, they are ready to begin the next stage in the jellyfish life cycle.

Hexacorals

Polyps with more than 8 tentacles and septa, typically in cycles of 12...

Physalia (draw)

Portuguese man-of-war: not a typical Siphonophore. It has specialized polyps, tentacles, and medusae under water that entrap fish. a floating gas-filled top with an angled fan that is driven by the wind. Has especially long nematocysts.

Order pennatulacea

Ptilosarcus: A sea pen

Mesoglea

Secreted by both tissue layers, it's function is structural, and may also aid in buoyancy and in insulating certain nervous conduction pathways from adjacent ones.

Mesoglea (gonionemus)

Secreted by both tissue layers, it's function is structural, and may also aid in buoyancy and in insulating certain nervous conduction pathways from adjacent ones.

Scyphozoan: What causes the swimming contractions? Where are the contractile elements located?

Subumbrella: conducts pulses rapidly and controls pulsations of the bell. Swimming muscles consist of circular and radial muscle fibers in ectoderm cells in the subumbrella.

Acontia (Metridium)

The slender projections from the bottom. secretes digestive enzymes.

Order stolonifera

Tubipora: organ pipe coral

Ephyra

When the polyp hydroid colony is ready to transform, the stalk portion of its polyps begin to develop horizontal grooves. These grooves continue to deepen until the polyp resembles a stack of saucers. The topmost groove matures the fastest and eventually buds off as a tiny baby jellyfish also known as an ephyra. The budding process by which polyps release ephyra is asexual. The ephyra grow in size and become the adult (medusa) form of jellyfish.

Tentacles (Aurelia)

covered in nematocysts, used for swimming and food capture. Transfer food to mouth.

Cnidocytes

food capture, on tentacles and body (and gastrodermis?)

Comb rows

groups of cilia used for swimming by the Ctenophores

Siphonophores

includes the corals, hydroids, and true jellyfish. colonial. important predators.

Stony corals

marine corals that generate a hard skeleton.The skeleton of an individual scleractinian polyp is known as a corallite. It is secreted by the epidermis of the lower part of the body, and initially forms a cup surrounding this part of the polyp.

Which end of the planula larva will develop the mouth?

posterior end

Planula larva

stage of development most cnidarians go through. larval forms that resembles the ancestral form that gave rise to higher metazoa. A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species. The planula forms from the fertilized egg of a medusa, as the case in scyphozoans and some hydrozoans, or from a polyp, as in the case of anthozoans.

Are the skeletons of stone corals and gorgonians both endoskeletons? Exoskeletons?

stony corals have exoskeleton Gorgonians have endoskeleton

Oral Disc (Metridium)

the oral disc and the tentacles attached to it b. the mouth (the opening in the oral disc) - the mouth leads into a gullet which is a passageway leading into the gastrovascular cavity c. the pedal disc (basal disc), which is the point of attachment to the substrate

Mouth (Metridium)

the oral disc and the tentacles attached to it. the mouth (the opening in the oral disc) - the mouth leads into a gullet which is a passageway leading into the gastrovascular cavity