SPONGE (Lat. spongia, from (ik. aroryla, sponge; connected with Lat. fungus, mushroom). A group of animals representing a distinct branch or phylum, Porifera. The sponges are many-celled animals, with three cell-layers, with out a true digestive cavity, supported usually by calcareous or siliceous spieules, the body-mass permeated by ciliated passages or containing minute chambers lined by flagellate, collared, monad-like cells. There is no true mouth-open ing, but usually an irregular system of inhalent pores opening into the eell-lined chambers or passages through which the food is introduced in currents of sea water, the waste particles passing out of the body by a single but more usually by many cloacal openings (oscula ). Sponges are hermaphroditic, multiplying by fer tilized eggs, the passing through a morula and a gastrula stage.
Sponges are divided, according to the nature of the skeleton or supporting fibres or spienles, into two orders: (I) Caleispongiw, in which the spicules are calcareous, and (2) Silicispongice, or glass sponges, in which the spicules are si liceous, or horny and fibrous, as in the bath sponges, when spongin instead of silica forms the supporting framework. Examples of the siliceous sponges are the Venus's flower-basket (Euplectella) and allied deep-sea forms, such as Hyalonema, lioltenia, etc. To the second order also belongs the fresh-water sponge (Spon gilla), which grows in lakes or sluggish streams. These differ from other sponges in producing statoblasts or winter buds, formed by the proto plasm dividing into round bodies as large as a pin's head and enveloped by a dense membrane. thus enabling the species to survive freezing cold or droughts.
Certain sponges bore into shells, causing them to disintegrate. For example, Cliona sul phurea has been found boring into various shells, such as the oyster, mussel, and scallop; it also spreads out on all sides, enveloping and dis solving the shell. It has even been found to penetrate one or two inches into hard statuary marble. Cliona also dis integrates coral.
Of the marketable sponges there are six species, with numerous varieties. They are avail able for our use from being simply fibrous, hav ing no siliceous spicules. The Mediterranean sponges are the best, being the softest ; those of the Red Sea are next in quality, while our West Indian species are coarser and less durable. Our glove-sponge (Spongin tubulifera) corresponds to Spongia Adriatica, which is the Turkey cup sponge and Levant toilet sponge of the Mediter ranean. Spongia gossypina, the wool sponge of Florida and the Bahamas, corresponds to Spongia equine, the horse or bath sponge of the Alediter ranean. This wool sponge of Florida attains under favorable circumstances a weight of one tenth pound, in six months, and reaches a size of commercial value in a year.
Fossil sponges are known in rocks of all ages. They appear first in the Cambrian as Proto spongia and Archzeoscyphia, representing the hexactinellids and lithistids. They are repre sented in the Ordovician by the curious Brachio spongia, and a number of irregular forms; in the Silurian by Astrxospongia, Astylospongia; in the Devonian by llindia and the Dietyospongi dx, which latter such great expansion in the shallow seas of western New York during Chemung time. Receptaculites is a peculiar sponge that is common in the Ordovician. Dur ing the Mesozoic sponges attained a great de velopment, became especially abundant during the Cretaceous period, and declined during the succeeding Tertiary. Noteworthy Cretaceous genera are Ventriculites and Cwloptychium.
BIBLIOGRAPHY. Hyatt, "Revision of North Bibliography. Hyatt, "Revision of North American Poriferre," in Memoirs Boston Society of Natural History (vol. ii., Boston, 1S75) ; Rauff, "Pakeospongiologia," in Pahrontographiea, vol. xl. (Berlin. 1S93) ; Hinde, Catalogue of Fossil Sponges of the British Museum (London, ISS3) ; AaII and Clarke, "A Memoir on the Paleozoic Reticulate Sponges Constituting the Family Dictyospongidte," in Memoirs of the New Tort.; State Museum, vol. ii. (Albany, IS9S).