BIO2231 - Sponges Flashcards

1
Q

Definition

Metazoa

A
  • Multicellularity with differentiation of cells
  • Blastula stage in development

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2
Q

Definition

Synapomorphies

A

Characters shared within a group

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3
Q

Definition

Autapomorphies

A

Characters that define different groups

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4
Q

Key points

Metazoa?

2 points.

A

Animals

  • Multicellular
  • Blastula stage in development

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5
Q

Key points

Porifera

3 points.

A
  • Cell aggregates
  • No germ layers
  • No true tissues, organs or gut

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6
Q

Key points

Eumetazoa

4 points.

A
  • True tissues
  • Gastrula stage
  • Germ layers
  • Digestive cavity (gut)

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7
Q

Cnidaria

3 points.

A
  • Two germ layers (diploblastic)
  • Radial symmetry
  • No anus

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8
Q

What is diploblastic?

A

Having a body derived from only two embryonic cell layers

(ectoderm and endoderm, but no mesoderm), as in sponges and coelenterates.

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9
Q

What is the advantages of Multicellularity?

2 points.

A
  • Size
  • Complexity

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10
Q

Multicellularity

Why not become one big cell?

A
  • SA/V ratio
  • structural integrity of cell membrane and cell division machinery

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11
Q

What is the impact of Increasing complexity?

2 points.

A

Compartmentalisation

  • Specialised cells for certain tasks = greater efficiency
  • BUT loss of independence for cells = greater vulnerability to injury

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12
Q

What are the advantages of increased body size?

6 points.

A
  • Efficiencies of scale (bigger is better)
  • Buffers against environmental fluctuations
  • Easier to retain heat for metabolism
  • Development of specialised body compartments
  • Better in attack (as predators)
  • Better for defence against predators

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13
Q

What are the Consequences of body size?

3 points.

A

Changes in surface to volume ratios limit exchange of oxygen and nutrients

Necessitates specific body shapes:

  • Sponge like
  • Flat sheets (bell/cup shape)
  • Tubes

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14
Q

How can an animal be a shape other than flat/long/spongy?

4 points.

A

Need to develop delivery systems

Diffusion no longer adequate → evolution of:

  • fluid filled body cavities
  • circulatory systems
  • respiratory systems
  • excretory systems

Note: Has Metabolic costs (e.g. pumping)

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15
Q

What will you not find in sponges?

3 points.

A
  • Gastrula stage with two germ layers
  • A digestive cavity (gut)
  • True tissues

General rule is above are absent in sponges … but that could be wrong

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16
Q

Describe

Phylum Porifera

6 points.

A
  • Cell aggregates with different cell types
  • Embedded in protein matrix (mesohyl)
  • Skeletal fibres (collagen, spongin) and spicules
  • Gastrulation absent or unusual
    • No mouth
    • No digestive cavity

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17
Q

What is ECM?

A

Extra Cellular Matrix
(mesohyl)

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18
Q

What are the characteristics of

The Sponges?

6 points.

A
  • Aquatic only (mainly marine)
  • Free swimming larvae
  • Sessile adults
  • Filter feeders (intracellular digestion)
  • Ancient (>700 my)
  • Diverse (5000 spp.)

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19
Q

What is the form of Phylum Porifera ?

4 points.

A
  • Structurally arranged to maximise surface area
    • Cells are arranged around a canal system
    • Supported by mesohyl with spicules Hickman
  • Skeleton composed of coarse spongin fibres (modified collagen) and/or needle like spicules of calcium carbonate or silicon dioxide

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20
Q

What is the body wall of Phylum Porifera?

3 points.

A

Body wall composed of

  • outer layer = pinacoderm
  • inner flagellated layer = choanoderm
  • connective layer = mesohyl

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21
Q

What are the cell types of Phylum Porifera?

9 points.

A
  • Pinacoderm
    • Pinacocytes = body wall cells
    • Porocytes = pore lining cells
  • Choanoderm
    • Choanocytes = flagellated cells that move water and do feeding
  • Mesohyl
    • Archeocytes = can differentiate into other cell types
    • Collencytes spongocytes , sclerocytes = secretory cells that produce the matrix
    • Oocytes and spermatocytes = reproductive cells

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22
Q

How do Phylum Porifera feed?

5 points.

A
  • Beating flagellum on choanocytes creates current
      * sucks water through pores in body wall
      * expels from atrium through opening, osculum
  • Water current food, gas exchange and waste removal
  • Filter feeders fine, suspended organic material microvilli of choanocyte trap small particles

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23
Q

Phylum Porifera

What is the Aquiferous System Morphology?

3 points.

A
  • Asconoid = vase/pipe shaped
  • Syconoid = vase with folded walls
  • Leuconoid = many chambers

Majority of sponges are Leuconoid

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24
Q

Phylum Porifera

Doe morphology indicate Clade?

2 points.

A

Grade ≠ Clade

  • All classes can show leuconoid grade of construction
  • Calcarea shows all grades of construction

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25
Q

Phylum Porifera

How do Phylum Porifera reproduce?

8 points.

A

Asexual

* Budding

Sexual

* Hermaphroditic
* No gonads
* Sperm carried into nearby sponges and fertilise eggs
* Usually viviparous
* Free swimming larva with flagellated cells

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26
Q

Phylum Porifera

How are Phylum Porifera classified?

4 points.

A

By body wall and spicules

  • Class Calcarea
    • Calcareous spicules , Pinacoderm present
  • Class Hexactinellida - glass sponges
    • Siliceaous spicules , Syncytial body wall
  • Class Demospongiae
    • Siliceous spicules with axial filament, Pinacoderm present leuconoid sponges, wide variety of shapes
  • Class Homoscleromorpha
    • Siliceous spicules without axial filament, pinacoderm with true basement membrane (incipient tissue)

95% of sponges are Demonsponges

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27
Q

Unique Demosponges?

5 points.

A

Carnivorous Deep Sea Demosponges

  • Discovered in mid 1990s
  • Several species
  • Hooklike spicules entrap crustacean and other invertebrate prey
  • No longer meet the sponge definition of:
    “sedentary, filter feeding metazoan, which utilizes a single layer of flagellated cells (choanocytes) to pump a unidirectional water current through its body.”
  • Appears to engage in extracellular digestion
    (as well as the intracellular typical of other sponges)

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28
Q

What are other things you probably never knew about
sponges?

6 points.

A
  • Sponges are important habitats 1 sponge was found with 16000 species in and on it
  • Extremely efficient biofilters a sponge the size of a 1 litre milk carton could filter a swimming pool in a day
  • The largest species can reach 5x5m
  • There are a number of freshwater species
  • Some sponges can move very slowly creeping
  • One of the first drugs for treating cancer, cytosine arabinoside, was isolated from a sponge

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