Sponges

Question 1

Why should we care about fossil sponges (and other sponge-like animals)?

Answer 1

a) Sponges represent the simplest multicellular animals with a fossil record spanning more than half a billion yearsb) some sponges & sponge-like organisms have been important reef-formers in the past (archaeocyathids in Cambriand, stromatoporoids in Silurian-Devonian, and calcisponges in Permian-Triassic)c) Some sponges are major contributors of carbonate sedimentd) Some sponges produce sliceous spicules that provide a source of silica for diagenetic chert formation.

Question 2

What are the Multicellular grades of organization of animal development?

Answer 2

a) Cellular Gradeb) Tissue Gradec) Organ Grade

Question 3

Cellular Grade:

Answer 3

Organism composed of many differentiated cells, which function semi-independently and are not joined together as tissues (e.g., Phylum Porifera and Archaeocyatha)

Question 4

Tissue Grade:

Answer 4

Simple organism with various types of tissues (e.g., Phylum Porifera & Archaeocyatha)

Question 5

Organ Grade:

Answer 5

Complex organism containing many highly developed organs, such as a heart, stomach, intestine, etc. (e.g., the true metazoans)

Question 6

Phylum Porifera:

Answer 6

(“pore-bearing organisms): Sponges with a porous body containing spicules and/or spongin; simple, aquatic, filter-feeding animals

Question 7

Class Hexactinellida:

Answer 7

(“Glass Sponges”): Relatively rigid sponges composed of loosely joined or tightly fused siliceous spicules; no spongin; exclusively marine, especially in deep water

Question 8

Class Hexactinellida Geologic Range:

Answer 8

CAMBRIAN TO HOLOCENE

Question 9

Class Calcarea:

Answer 9

(“Calcisponges”): Relatively rigid sponges composed of calcite spicules; no spongin; exclusively marine, mostly in shallow water; CAMBRIAN TO HOLOCENE

Question 10

Class Calcarea Geologic Range:

Answer 10

CAMBRIAN TO HOLOCENE

Question 11

Class Demospongea:

Answer 11

(“Demosponges”): Flexible sponges composed of soft spongin; with or without siliceous spicules; inhabit marine and fresh water; CAMBRIAN TO HOLOCENE

Question 12

Class Demospongea Geologic Range:

Answer 12

CAMBRIAN TO HOLOCENE

Question 13

Class Stromatoporoidea:

Answer 13

(“Stromatoporoids”): Hard, solid, sponge-like organisms composed of densely laminated skeleton of calcite and containing radiating “pillars” of calcite within the “laminae”; no evidence of spongin; exclusively marine, occuring mostly as reef-builders in shallow tropical waters; ORDOVICIAN TO CRETACEOUS

Question 14

Class Stromatoporoidea Geologic Range:

Answer 14

ORDOVICIAN TO CRETACEOUS

Question 15

Class Sclerospongia:

Answer 15

Hard, solid sponge composed of a densely laminated skeleton of aragonite or calcite plus soft spongin containing siliceous spicules; exclusively marine, occurring mostly in cryptic habitats in shallow tropical waters; ORDOVICIAN TO RECENT (not very important as fossils)

Question 16

Class Sclerospongia Geologic Range:

Answer 16

ORDOVICIAN TO RECENT

Question 17

Ostium:

Answer 17

Small pore in the sponge wall, through which water enters the body.

Question 18

Canal:

Answer 18

Tubular channel starting at an ostium and extending through the sponge wall.

Question 19

Spongocoel:

Answer 19

Large cavity in the interior of the sponge body

Question 20

Osculum:

Answer 20

Large opening, through which water is expelled from the spongocoel.

Question 21

Spongin:

Answer 21

The soft, flexible, organic material that makes many sponges “spongy”

Question 22

Spicules:

Answer 22

Tiny, hard, needle-like structures of either silica or calcite (not all sponges have these)

Question 23

Draw and label a diagram of typical sponge

Answer 23

See 4a

Question 24

Problematical Relatives? of Sponges:

Answer 24

StromatoporoidsArchaeocyathids

Question 25

Stromatoporoids:

Answer 25

laminated organisms that are usually classified in Phylum Porifera

Question 26

Laminae:

Answer 26

Individual, thin, calcite layers that make up the stromatoporoid skeleton

Question 27

Latilaminae:

Answer 27

Discrete units of multiple calcite laminae.

Question 28

Pillars:

Answer 28

Long calcite rods within the latilaminae; oriented perpendicular to the laminae.

Question 29

Mamelons:

Answer 29

Rounded bumps on the surface of a stromatoporoid skeleton

Question 30

Astrorhizae:

Answer 30

Star-like arrangement of radiating, branching grooves on the mamelons.

Question 31

Draw and label a diagram of a stromatoporoid:

Answer 31

See 4b

Question 32

Archaeocyathids:

Answer 32

cup-like organisms that are usually classified in a separate phylum

Question 33

Phylum Archaeocyatha:

Answer 33

(“ancient cup-like” organisms): Sponge-like organisms with a rigid calcite skeleton of two concentric, porous walls; simple, aquatic, filter-feeding animals.

Question 34

Class Regulares:

Answer 34

Archaeocyathids in which the skeleton lacks dissepiments; LOWER CAMBRIAN

Question 35

Class Regulares Geologic Range:

Answer 35

LOWER CAMBRIAN

Question 36

Class Irregulares:

Answer 36

Archaeocyathids in which the basal part of the skeleton has tiny, irregularly arranged, subhorizontal partitions, called dissepiments; LOWER CAMBRIAN

Question 37

Class Irregulares Geologic Range:

Answer 37

LOWER CAMBRIAN

Question 38

Outer wall:

Answer 38

Outermost of the two concentric walls of an archaeocyathid.

Question 39

Inner Wall:

Answer 39

Innermost of the two concentric walls of an archaeocyathid.

Question 40

Septa (parietal walls):

Answer 40

Rigid, radiating partitions that separate the outer and inner walls. (archaeocyathid)

Question 41

Intervallum:

Answer 41

Open space between the outer and inner walls. (archaeocyathid)

Question 42

Central cavity:

Answer 42

Open space inside the inner wall (archaeocyathid)

Question 43

Tip:

Answer 43

Pointed bottom end of the archaeocyathid skeleton.

Question 44

Holdfast:

Answer 44

Calcareous projections of the skeleton near its tip, which serve to anchor the arcaeocyathid skeleton in place in the sediment

Question 45

Draw and label a diagram of a typical archaeocyathid:

Answer 45

See 4b