Sponges Flashcards
Why should we care about fossil sponges (and other sponge-like animals)?
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.
What are the Multicellular grades of organization of animal development?
a) Cellular Gradeb) Tissue Gradec) Organ Grade
Cellular Grade:
Organism composed of many differentiated cells, which function semi-independently and are not joined together as tissues (e.g., Phylum Porifera and Archaeocyatha)
Tissue Grade:
Simple organism with various types of tissues (e.g., Phylum Porifera & Archaeocyatha)
Organ Grade:
Complex organism containing many highly developed organs, such as a heart, stomach, intestine, etc. (e.g., the true metazoans)
Phylum Porifera:
(“pore-bearing organisms): Sponges with a porous body containing spicules and/or spongin; simple, aquatic, filter-feeding animals
Class Hexactinellida:
(“Glass Sponges”): Relatively rigid sponges composed of loosely joined or tightly fused siliceous spicules; no spongin; exclusively marine, especially in deep water
Class Hexactinellida Geologic Range:
CAMBRIAN TO HOLOCENE
Class Calcarea:
(“Calcisponges”): Relatively rigid sponges composed of calcite spicules; no spongin; exclusively marine, mostly in shallow water; CAMBRIAN TO HOLOCENE
Class Calcarea Geologic Range:
CAMBRIAN TO HOLOCENE
Class Demospongea:
(“Demosponges”): Flexible sponges composed of soft spongin; with or without siliceous spicules; inhabit marine and fresh water; CAMBRIAN TO HOLOCENE
Class Demospongea Geologic Range:
CAMBRIAN TO HOLOCENE
Class Stromatoporoidea:
(“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
Class Stromatoporoidea Geologic Range:
ORDOVICIAN TO CRETACEOUS
Class Sclerospongia:
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)
Class Sclerospongia Geologic Range:
ORDOVICIAN TO RECENT
Ostium:
Small pore in the sponge wall, through which water enters the body.
Canal:
Tubular channel starting at an ostium and extending through the sponge wall.
Spongocoel:
Large cavity in the interior of the sponge body
Osculum:
Large opening, through which water is expelled from the spongocoel.
Spongin:
The soft, flexible, organic material that makes many sponges “spongy”
Spicules:
Tiny, hard, needle-like structures of either silica or calcite (not all sponges have these)
Draw and label a diagram of typical sponge
See 4a
Problematical Relatives? of Sponges:
StromatoporoidsArchaeocyathids
Stromatoporoids:
laminated organisms that are usually classified in Phylum Porifera
Laminae:
Individual, thin, calcite layers that make up the stromatoporoid skeleton
Latilaminae:
Discrete units of multiple calcite laminae.
Pillars:
Long calcite rods within the latilaminae; oriented perpendicular to the laminae.
Mamelons:
Rounded bumps on the surface of a stromatoporoid skeleton
Astrorhizae:
Star-like arrangement of radiating, branching grooves on the mamelons.
Draw and label a diagram of a stromatoporoid:
See 4b
Archaeocyathids:
cup-like organisms that are usually classified in a separate phylum
Phylum Archaeocyatha:
(“ancient cup-like” organisms): Sponge-like organisms with a rigid calcite skeleton of two concentric, porous walls; simple, aquatic, filter-feeding animals.
Class Regulares:
Archaeocyathids in which the skeleton lacks dissepiments; LOWER CAMBRIAN
Class Regulares Geologic Range:
LOWER CAMBRIAN
Class Irregulares:
Archaeocyathids in which the basal part of the skeleton has tiny, irregularly arranged, subhorizontal partitions, called dissepiments; LOWER CAMBRIAN
Class Irregulares Geologic Range:
LOWER CAMBRIAN
Outer wall:
Outermost of the two concentric walls of an archaeocyathid.
Inner Wall:
Innermost of the two concentric walls of an archaeocyathid.
Septa (parietal walls):
Rigid, radiating partitions that separate the outer and inner walls. (archaeocyathid)
Intervallum:
Open space between the outer and inner walls. (archaeocyathid)
Central cavity:
Open space inside the inner wall (archaeocyathid)
Tip:
Pointed bottom end of the archaeocyathid skeleton.
Holdfast:
Calcareous projections of the skeleton near its tip, which serve to anchor the arcaeocyathid skeleton in place in the sediment
Draw and label a diagram of a typical archaeocyathid:
See 4b
