Marine invert lecture exam 2

Protozoa, porifera, ctenophora, and cnidaria

What are perisarcs and coenosarcs?

The perisarc is the structure that hydrozoan polyps attach to, and in some species grows around the polyp for them to retreat into to avoid predation. The coenosarc is a living structure, and serves as the direct attachment point between the perisarc and the polyp.

Classify this organism. What stage is it in?

This organism is in phylum Cnidaria, subphylum Medusozoa, class Hydrozoa, and order Anthoathecata.

It is the colonial polyp stage of fire coral Millepora

Match the image of typical Anthoathecata medusae

Match the image of the blue button Porpita, a floating coral polyp colony

What phylum, subphylum, class, and order is this medusa? Describe their habitat and diet.

Phylum Cnidaria

Subphylum Medusozoa

Class Hydrozoa

Order Lepthothecata

Habitat: attached to structures as polyp, planktonic as medusa

Feeding: carnivore

Match this anthoathecatan medusa to the correct colonial polyp stage.

What phylum, subphylum, class, and order is this medusa? Describe their habitat and diet.

Phylum Cnidaria

Subphylum Medusozoa

Class Hydrozoa

Order Siphonophorae

Habitat: Planktonic

Feeding: Carnivore

What phylum, subphylum, class, and order is this organism? Describe their habitat and diet.

Phylum Cnidaria

Subphylum Medusozoa

Class Hydrozoa

Order Siphonophorae

Habitat: Planktonic

Feeding: Carnivore

Correctly identify the two labeled parts in this image.

1. Pneumatophore

2. Tentacle

What phylum, subphylum, and class is this organism? Name all the labeled parts of this organism.

Phylum Cnidaria

Subphylum medusozoa

Class cubozoa

1. Exumbrella

2. Pedalia

3. Tentacles

If an organism is in class cubozoa, what phylum and subphylum is it? What habitat and feeding do they use?

Phylum Cnidaria

Subphylum medusozoa

Habitat: attached to structure as a polyp, planktonic as medusa

Feeding: carnivore

What are all the labeled parts to this organism?

1. Planula

2. Scyphula (planula just settled)

3. Scyphistoma (polyp)

4. Strobila

5. Ephyra

6. Lappet

7. Rhopalium

8. Oral arm

9. Manubrium and mouth

What are all the labeled parts to this organism?

10. Medusa

11. Exumbrella (bell)

12. Rhopalium

13. Tentacles

14. Oral arm

15. Gonads

16. Radial canals

17. Ring canal

What phylum, subphylum, class, and subclass is this organism?

This medusa diagram is:

• Phylum Cnidaria

• Subphylum Medusozoa

• Class Scyphozoa

• Subclass Discomedusae

What phylum, subphylum, class, and subclass is this organism?

• Phylum Cnidaria

• Subphylum Medusozoa

• Class Scyphozoa

• Subclass Discomedusae

It is the same as this image.

Classify this organism:

Phylum: Cnidaria

Subphylum: Anthozoa

Class: Otocorallia

Order: Scleralcyonacea

If an organism is in subclass Discomedusae, what habitat and feeding does it have?

Habitat: attached to structure as polyp, planktonic as medusa

Feeding: carnivore

Classify this organism and identify the labeled parts

Phylum Cnidaria

Subphylum Anthozoa

Class Octocorallia

Order Scleralcyonacea

1. primary polyp; 2. secondary polyps; 3. sand anchor of primary polyp

What is this?

Classified as: Cnidaria:Anthozoa:Octocorallia:Malacalcyonacea

It is a gorgonian protein skeleton forming axial rod (soft tissue removed)

What is this?

Classified as: Cnidaria:Anthozoa:Octocorallia:Malacalcyonacea

It is the calcified skeleton of organ pipe coral

What is this? Identify the labeled parts.

Classified as:

Phylum Cnidaria

Subphylum Anthozoa

Class Octocorallia

Order Malacalcyonacea

1. polyp; 2. tentacle; 3. axial rod; 4. gastrovascular cavity

What are these?

Phylum Cnidaria

Subphylum Anthozoa

Class Hexacorallia

Order Zoantharia

What order is this organism?

Order Corallimorpharia

What class and order order is this organism? Identify the labeled parts.

Class Hexacorallia, Order Scleractinia

1. theca of colonial polyp; 2. sclerosepta; 3. solitary polyp

Approximately how many species are in Cnidaria?

~13,000 spp

What is the general body plan of a cnidarian?

• Dipoblastic (2 of 3 germ layers)

• Radial symmetry (sometimes bilateral)

• Tentacles with cnidae

• Epidermis: nerve net and muscles

• Mesoglea: jelly of proteins, carbs, etc

• Gastrodermis: digestive system, generates muscles

What life cycle do most cnidarians have?

Dimophic, meaning polyp and medusa stages

Diffusion serves what functions in cnidarians?

Excretion and respiration

What is the diet and digestion of cnidarians?

They eat plankton and small fish using a gastrovascular cavity

What modes of reproduction do cnidarians have? What are their larvae called?

• Monoecious or dioecious

• Planula larvae (asexual budding forms colony)

Describe the cnidarian nervous system

They have a nerve net, medusa may have ocelli and/or statocysts

What do ocelli and statocysts do?

Ocelli are light/dark detectors, statocysts are for orientation

What do hydrozoans do and don’t have?

DON’T have:

• Cells within mesoglea

• Cnidocytes in gastrodermis

• Mesentaries

• Phopalia

DO have:

• Colonial polyps (usually)

• Velum on medusa

Describe the life cycle of hydrozoans

Planula —>Actinula

What larval stage is unique to hydrozoans?

Actinula

Describe order trachymedusae within class hydrozoa

• NO POLYP

• Size range: a few cm

• Thick rings of tissue on bell with nematocysts (bell can sting)

• Tentacles on bell margin

• Margin not lobed

• Statocyst present on medusa

• Gonads on radial canals

• Deep water

Describe order narcomedusae within class hydrozoa

• Usually no polyp

• Few cm size

• Tentacles on BELL, not margin

• Bell margin- lobed

• Statocyst ARE present

• Gonads on manubrium

• Deep water

What are the differences between the hydrozoans in narcomedusae vs.trachymedusae?

Narcomedusae: tentacles on bell, bell margin IS lobed, gonads on manubrium

Trachymedusae: tentacles on bell margin, margin NOT lobed, gonads on radial canals

Describe order actinulida

• Simplified medusa (reduced bell with tentacles)

• Size: few mm

• Interstitial (too small to be infauna)

How is order stauromedusae classified?

Phylum Cnidaria—> Subphylum Medusozoa—>Class Staurozoa —> Order Stauromedusae

Describe order stauromedusae

• Mesoglea with cells

• Gastrodermis with cnidocytes

• Solitary polyp (benthic)

• Cold water (deep or shallow)

• Minor part of food web, unique morphology

Describe a stauromedusae medusa

• Benthic (attached)

• Finger-shaped bell looks like polyp

• ~cm

• 8 lobes

• Capitate (ball shape) tentacles

What is the life cycle of a stauromedusae?

Planula larvae —> stauropolyp —>medusa

Describe class scyphozoa

• Mesoglea with cells

• Gastrodermis with cnidocytes

• Habitat: all oceans

• Polyp and medusa

• Medusa planktonic without velum, rhopalia sensory structure

Describe the life cycle of scyphozoans

Planula larvae—> Scyphistoma/Polyp (benthic)—> undergoes strobulation to form Strobila —> ephyra —> adult medusa

How are organisms of order coronate classified?

Phylum cnidaria—> Class scyphozoa —> Subclass Coronamedusae —> Order Coronatae

Order coronatae is the only order in coronamedusae

What is unique about jellies in order coronatae?

• They have a bell with a coronal groove

• Also have pedalia

What distinguishes subclass discomedusae?

They have a bell without a coronal groove AND lack pedalia

Describe class cubozoa

• Mesoglea with cells

• Gastrodermis with cnidocysts

• Polyp = solitary and benthic

• Medusa = planktonic 4-sided bell

  • Velarium

  • Pedalia

  • Rhopalia present

  • Eyes with lens

• Very dangerous sting

Describe the life cycle and habitat of cubozoans

• Life cycle: planula—> polyp —> medusa

• Habitat: tropical shallow water

What famous cubozoan has a very dangerous sting?

Chironex fleckeri

What is used to identify order caroybdeida?

They have unbranched pedalia with a single tentacle attached

What is used to identify order chirodropida?

Pedalia ARE branched, with multiple tentacles attached to each.

What subphylum are myxosporeans in? Describe them

Subphylum endocnidozca

• Intracellular parasites, form capsules

• Life cycle:

  • infective actinospores (polychaete host)

  • infective myxospores (vertebrate host)

Describe subphylum anthozoa

• Mesoglea with cells

• Gastrodermis with cnidocytes

• Polyp: solitary or colonial, internal mesentaries

• NO MEDUSA STAGE- only planula larvae and polyp

• Habitat: benthic, all oceans

What are the defining features of octocorallians?

• Primarily colonial

• 8 mesentaries

• 8 pinnate tentacles

• 1 siphonoglyph

Describe order scleralcyonacea (within class octocorallia)

• Branching colonial polyp

• CaCO3 central axial support

• Some polyps are dimorphic

• Some external skeleton

• Habitat: attached to strucutre (reefs)

  • a few sand specialists (sea pens)

Describe class hexacorallia

• Solitary or colonial

• 6-fold symmetry

• Non-pinnate tentacles

How is order ceriantharia categorized?

Phylum cnidaria —> Subphylum Anthozoa —> Class Hexacorallia —> Order cerantharia

Describe order cerantharia

• “tube anemones”

• Solitary, several cm

• Build tubes with sand, mucus and ptchocysts

• Tentacle formation = double whorl

  • outer whorl - long and thin

  • inner whorl - short

• Unpaired mesenteries

• Siphonoglyph- 1 (small)

• Support - hydroskeleton (no spicules/axial rod)

• Habitat: sand and mud

What is a ptychocyst?

A type of cnidocyst

Describe order antipatharia (hexacorallia)

• black corals

• body: colonial, cm-mm, branched

• single whorl of 6 tentacles

• unpaired mesentaries

• 1 siphonoglyph

• Axial hard protein support rod

• deep reefs

Describe order actiniaria

• Solitary

• mm- several cm

• Single whorl of tentacles

• Paired mesentaries

• 2 siphonoglyphs

• hydroskeleton support

• benthic

• asexual budding (clones break off and walk away)

• mucus keeps them wet in intertidal

Describe order zooantharia (Class Hexacorralia)

• “mat anemones”

• Colonial (thin)

• 2 whorls of tentacles

• Paired mesentaries

• 1 siphonoglyph

• Hydroskeletal support

• Glue sand grains to outside for protection

• Attached to surfaces, epizoic

Describe order corraliomorpha (class hexactinellida)

• Colonial or solitary body

• mm-cm in size

• Multiple whorls of capitate tentacles

• paired mesentaties

• NO siphonoglyph

• Hydroskeleton

• Attached to hard surfaces

Describe order scleractinia (class hexacorallia)

- Colonial

- Colony size a few cm to multiple m depending on age

- Tentacles are single whorl, variety of shapes

- Paired Mesentaries

- Siphonoglyphs- NONE

- Supoort- CaCO3 skeleton, forms theca with individual polyps separated by sclerosepta

What does it mean if a cnidarian is ahermatypic?

- Ahermatypic = non reef building

- Most are solitary

- Usually without zooxanthellae

- Shallow or deep water

What does it mean if a cnidarian is hermatypic?

- Hermatypic = reef building

- Most reefs are these guys

- Usually colonial

- Usually have zooxanthellae

- Shallow, clear water

- Mass spawning- most inverts spawn with the coral

What is the center of origin for corals, at a species level?

The pacific, specifically the indo-pacific

What is the main problem for corals in the Indo-Pacific?

Deforestation, which results in sediment runoff

What parts are fringing reefs comprised of?

• Patch reef (near shore)

• Main reef

• Bank reef (deep offshore)

The fringing reef may not have all 3 of these components.

True or False: Any circular reef can technically be considered an atoll.

True, but many people define atolls by volcanic activity

What are the reef zones?

• Shoreline/beach

• Lagoon (between shoreline and start of reef)

  • Grass beds

  • Hardpan (gorgonians, fans)

  • Nursery

• Patch reef

• Back reef (rubble from damage, inverts, stony corals)

• Reef crest (dry at low tide)

• Forereef (spur/groove, most diverse)

• Sand channel (mostly CaCO3 shells)

• Bank reef (70-80 ft)

• Deep reef (-90 ft, black corals)

• Wall (dropoff)

How much more diverse are pacific reefs than caribbean reefs?

10 times more (species diversity)

What is the scientific name for elkhorn coral?

Acropora palmata

What do corals and anemones exposed at low tide do to protect themselves?

They secrete a mucus that covers them and protects them.

When were the first signs of coral bleaching? When did big bleaching events start to happen?

• First evidence: 1980s and 1990s

• Big bleaching: 1990s and 2000s

Bleaching events are more drastic in shallow water

How does sedimentation affect coral? How about eutrophication?

• Sedimentation: cuts out light and smothers coral

• Eutrophication: lowers light and affects nutrients

What is cyanide fishing? How does it affect coral?

Cyanide fishing occurs mainly in the Pacific, and happens when bottles of cyanide are squirted into a reef to flush out fish. This is mostly done to catch fish for the aquarium trade, but results in death for fish too close and for corals.

Why is dynamite fishing controversial?

It often results in people blowing themselves up and dying (karma tbh)

What items can physically damage coral reefs?

• Lost fishing gear

• Anchors

• Ships

• unethical tourism (“death by a thousand cuts”)

What does tripoblastic mean?

3 germ layers

Describe Phylum Chaetognatha

• 13 spp

• Habitat: all oceans, planktonic (one benthic)

• Digestion:

  • Flow-through

  • Carnivores (eat copepods)

• Diffusion for respiration and excretion

• Reproduction- monoecious, direct

• Nervous: ganglia in head, nerve net, ocelli, cillia

• Circulation: sinuses

• Ecology: predators on plankton

Describe the body plan of chaetognatha

5-100 mm

Arrow shape

Head- spines

Trunk: long part of the body, under head

Fins: most cases tail fin (some trunk)

Muscles: longitudinal and circular

Describe phylum cycliophora

Species example: Symbion pandora

• Body: feeding stage main part of life cycle

  • 350-500 um

  • Adhesive disk

  • Trunk

  • Buccal funnel

• Habitat: epizoic

• Digestion: u-shaped gut (eat small particles)

• Circulation: none

• Diffusion for excretion and respiration

• Reproduction: pandora larva

• Nervous system: ganglia and nerve cords

• Commensalism in lobster mouth

Explain the life stages of Cycliophorans

• Pandora larva (asexual) = feeding stage

• Colonizes the same lobster when reproducing

• Prometheus larvae (male) attache to feeding stage larvae

• Chordoid larvae move to other lobsters when shed during molt

Describe Phylum Platyhelminthes

• 20,000 spp

• Many parasitic (know free-living spp)

• Benthic (some can swim, not long)

• Digestion: pharynx and gut, not complete

• Carnivores

• Circulation- none

• Respiration: diffusion

• Excretion: Protonephridia

• Reproduction: monoecious, direct development

• Nervous system: ganglia, ladder nerves, ocelli near ganglia

  • some have statocyst

• Regeneration

What are protonephridia?

It is the adapted excretion system platyhelminthes worms use to speed up diffusion. Literally, it means “first kidney”

Describe the body form of platyhelminthes worms

• Acoelomate (no body cavity)

• mm-cm in size

• Multiciliated epidermal cells

• Rhabdite glands

• Longitudinal and circular muscle tissues (long)

• Mouth in middle of body

Describe Phylum Gnathostomulida

• 100 spp

• Body: 300 um - 3 mm, elongate shape

  • big jaws, plate-like

• Monociliated epidermal cells

• Long and circular muscle layers

• Habitat: Interstitial anoxic mud

• Digestion: pharynx and gut (incomplete)

• Circulation: absent

• Excretion: protonephridia

• Respiration: diffusion

• Reproduction: monoecious, direct development

• Nervous: ganglia, net, 2 cords

  • ciliary pits, bristles

• Ecology: feed on bacteria

Describe order anthethocata. What class is it in?

• Polyp = benthic and colonial

  • Athecate (perisarc stops at polyp)

• Specialized zooids:

  • Dactylzooid - defense

  • Gonozooid - produces medusa

  • Gastrozooid - digestion

• Medusa:

  • taller than wide

  • planktonic

  • tentacles on margin

  • margin NOT lobed

  • No statocyst

  • gonads on manubrium

They are in class Hydrozoa.

Describe order Leptothecata. What class is it in?

• Polyp = benthic, colonial

  • Thecate - perisarc covers polyp

• Medusa:

  • Sometimes absent

  • Wider than tall

  • Tentacles on margin

  • Margin not lobed

  • Statocyst present

  • Gonads on radial canals

Class Hydrozoa

Describe order Siphonophorae within Class Hydrozoa

• Polyp and medusa present

• Colonial

• Swim/float

• Up to several m

• Zooids (repeating units)

  • Gastrozooid - feeding

    • Tentacle has branching called tentilla

  • Palpons - internal water/food movement

  • Gonozooids - produce medusa

  • Bracts - protection

• Nectophore/nectosome - swimming bell

• Pneumatophore - float

• Larva = siphonula

Describe suborder cystonectae. How is it classified?

Phylum Cnidaria —> Subphylum Medusozoa —> Class Hydrozoa —>Order Siphonophorae —> Suborder Cystonectae

• Nectosome absent

• Pneumatophore present

• Bracts absent

Describe suborder codonophora. How is it classified?

Phylum Cnidaria —> Subphylum Medusozoa —> Class Hydrozoa —>Order Siphonophorae —> Suborder codonophora

• Nectosome present

• Pneumatophore small or absent

• Bracts present

• Big size range

Describe order stauromedusae. How is it classified?

Phylum Cnidaria —> Subphylum Medusozoa —> Class Staurozoa —> Order Stauromedusae

• Mesoglea with cells

• Gastrodermis with cnidocytes

• Polyp = benthic, solitary

• Medusa:

  • Benthic (attached)

  • 8 lobes

  • Capitate tentacles

  • Few cm

• Life cycle: planula—>stauropolyp—>medusa

• Ecology: minor food web

What is cephalization?

When organs and structures are concentrated on the anterior portion of the body, forming a “head”