The phylum Porifera, consisting of about 10,000 known species, more commonly called “sponges,” are aquatic animals that first appeared in Precambrian (approximately 5 billion to 570 million years ago) times, characterized by much volcanic activity, in marine environments. Sessile (mostly immobile) animals that rely upon water currents for oxygen and food deliveries of dissolved organic matter, sponges have many pores (hence, the phylum nomenclature of Porifera). These animals are asymmetrical, lack tissue or organs, are classified taxonomically mainly by variations of spicule patterns into three major groups (Hexactinellida, [glassy sponges with 6-rayed spicules], Demospongia [which secrete a collagen-form called spongin], and Calcarea [calcareous sponges with excreted 3-4 rayed spicules and crystalline calcium carbonate{CaCO3}]) (Starr).
Sponges are mostly found in saltwater; however, many sponges thrive in arctic waters and in freshwater (Starr, et al.). Of saltwater marine Porifera, abiotic conditions are not a determining factor of aquatic community habitats. Some sponges are suited for reefs, as these sponges have a slower growth rate, while others thrive in mangrove habitats (Wulff). Evidence supports that marine sponges have a uniform worldwide microbial habitat, as well as a common history of evolution from ancient metazoans (Hentschel, et al.) The species of Spongilla lacustris is an interesting example of a sponge that thrives in brackish freshwater in places such as a sphagnum bog, a bog inhabited mostly by mosses of the genus Sphagnum (Sphagnales), in New Hampshire, USA (Frost, et al.) Porifera in extreme conditions of a sphagnum bog or of an Arctic sea have adapted to the harsh environments in many ways, especially by the means of reproduction via gemmules, a hard-coated minute mass of cells that survive the harshness then grow into mature sponges. Most sponges, however, are hermaphrodites, producing both sperm cells and egg cells. Many others reproduce asexually, breaking off into pieces, and, much like a severed piece of a hologram contains the information of the part as the whole, the piece of a Porifera that reproduces in this manner is capable of reproducing the whole.
Ecologically, sponges are threatened by the over-consumption of many Porifera in the $40 million dollar economic industry of their harvest. Mankind and womankind have found uses for Porifera since the ancient days. For example, most Classical Latin students know that the ancient Romans used a Porifera-on-a-stick in the public latrines of the Roman Empire. An ancient Roman on a latrine would dip the Porifera (one of the mostly spongin Demospongiae that lack spicules) into a stream of water powered by aqueducts in order to cleanse him/herself. (One would not wish to be downstream of too many others!) A recently discovered medical use of Porifera, especially of the Okinawan marine sponge (Agelas Mauritianus), is the medical use an extract of the sponge’s glycolipids (glycosphingolipids) has anti-tumor, anti-diabetes (type 1), as well as the property of stimulating the immune system (Haaf).
Works Cited
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Standing Biomass of the Freshwater Sponge Spongilla Lacustris." Ecology. 63.5
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Haaf, Wendy. “Sponge compound found to protect against diabetes.” Medical Post. 2
Oct. 2001: Health Module, ProQuest. Web. 5 Jul. 2011.
Hentscel, Ute; Hopke, Jorn; Horn, Matthias, Friedrich, Anja B., et al. “Molecular
evidence for a uniform microbial community in sponges from different oceans.”
Applied and Environmental Microbiology. 68.9 (2002): 4431. Sciences Module,
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Starr, Cecie, Ralph Taggart, Christine Evers, and Lisa Starr. Biology: The Unity and
Diversity of Life. 12th ed. Belmont, CA: BrooksCole Pub Co, 2009. Print.
Wulff, Janie L. “Trade-Offs in Resistance to Competitors and Predators, and Their
Effects on the Diversity of Tropical Marine Sponges.” Journal of Animal Ecology. 74.2
(2005): 313-21. http://www.jstor.org/stable/3505620 Web. 5 Jul. 2011.