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.