(Siliceous Sponge)

  [Singular noun --Sponge (siliceous)]:  Fr- éponge (siliceux) ; Ger-Schwamm (kieselartig) ;
Nor-svamp (kiselholdig); Rus- губчатый (кремнистый))

Venus' Flower Basket, Euplectella aspergillum Owen, 1841, (greatest dimension ~ 25 cm) from the Philippines. (© photo by Heidi Reed, from  Attention is also directed to the microphotographs of Hartman (1981).

Phylum, Porifera; order,Lyssacinosida; class, Hexactinellida;  family, Euplectellidae:  This sponge (Euplectella aspergillum Owen, 1841) consists of typically six-armed spicules (see electron micrographs in De Vos et al, 1991, p. 96) that constitute a slightly curved, roughly cylindrical skeleton that is commonly between 15 and 30 cm long (see Figure). Chemically, the spicules are ultra fine-grained hydrated silica (SiO2 ·nH2O);  this silica has been characterized variously as "hydrated SiO2 in an amorphous state[,] ... opal ... [and as hydrated SiO2 with] indications of the transition of SiO2 into a crystalline state, into quartz" (Vinogradov, 1953, p.183).  Whatever their true composition, I have been intrigued by the dainty complexity and beauty of the lattice-like arrangement of the spicules of these sponges ever since I first saw one as a student at Colgate University in 1941;  I second Pechenik's (2005) characterization of these sponges as "marvels of structural complexity and symmetry." I have often thought of them as psychodelicate.
    Color - white
    H.   5 - 5½
    S.G.  ~2.04
    Light transmission - translucent to semitranslucent
    Luster - porcelaneous to subvitreous
    Breakage - brittle; irregular to micro-conchoidal
    Miscellaneous -  Fluoresces  -- reportedly because of the "presence of fluorescent bacterial embedded in its structure" (Ivanhoe..., 2006)

 USES:  Venus' flower baskets' chief role is as decorative pieces in collections and other displays.  They are, in my opinion, among the most appropriate natural objects for such use.   They also are sometimes given as wedding presents in Japan -- see paragraph three of the REMARKS. 

OCCURRENCES & NOTEWORTHY LOCALITIES:   Deep (35 - 5,000 m) in the ocean along the eastern coast of Asia and sporadically around the East Indies and the Philippine islands.
REMARKS: Although I had always thought the name "Venus's Flower Basket" was probably based on this sponge's funnel or vase-like shape, according to the Encyclopædia Britannica (2006), "The name Venus's flower basket derives from the sponges' delicate, white, latticelike skeletons."   An alternative derivation is the designation was given "because the Roman goddess Venus is often shown holding a basket of flowers." (Ivanhoe..., 2006). In any case, the species was originally described and named by Richard Owen, the first director of the British Museum of Natural History.

When found, the skeletons include at least a thin layer of organic material.  Although the procedures for removing the soft parts appears to be a trade secret (i.e., I have found no record of such and have received no responses to inquiries), the procedure for preparation of silica sponge spicules for study by electron microscopy has been outlined:  "First treat ... with a 5.25% solution of sodium hypochlorite in water.  After a minimum of 30 min (sic)  in this solution ... [they were] washed in several changes of water... then boiled in concentrated nicric [sic] acid and washed in at least four changes of distilled water followed by one rinse in 95% ethanol ..." (Hartman, 1981, p.453-454) and, of course, dried.  Fortunately, the virtually pure white skeletons are available in the marketplace.

There is said to be a symbolism attached to giving of these sponges as wedding presents in Japan: "When the Venus flower basket is small, tiny shrimp swim in and out of it. However, as the Venus Flower Basket grows it seals off the open upper end, and at the same time the shrimps grow so that they cannot swim through the side of the Venus flower basket. As this happens, a pair of shrimps, one male and one female, will stay inside the Venus flower basket and become trapped there. This pair of shrimps will spend the rest of their lives inside that Venus flower basket¶ To the Japanese this is a symbol of eternal love and being happily married forever." (Edwards, 2005)  It also is a fine example of symbiosis.

Recently, a team of researchers has raised the question as to whether these sponges' composition and makeup are such that they are luminescent, even in the dark ocean depths where they live, and thus attract their prey and the symbiotic shrimps that live within them:  "We wonder whether the observed remarkable fiber-optical capabilities of these spicules are actually used by this species in the wild or are accidental ... [Granted] sponge E. aspergillum ... typically occurs at depths at which the paucity of ambient sunlight, high pressure, and hydrothermal vents lead to bio- or chemiluminescence being the only feasible sources of illumination.  [But,] Our results suggest that if such sources exist within or in close association to the basalia of E. aspergillum, their light might be efficiently used and distributed by the sponge.  [And,] Such a fiberoptical lamp might potentially act as an attractant for larval or juvenile stages of these organisms and symbiotic shrimp to the host sponge."
(Aizenberg et al., 2004).

From another standpoint, it is noteworthy that the relatively long (5-15 cm), thin (40 - 70 μm in diameter) "anchorage spicules (basalia)" secreted at the bases of these glass sponges have "technological advantages over man-made versions" of fiber optic fibers.  Consequently, the process(es) and conditions under which these sponges fabricate their basalia is of great interest to those involved in the production of fiber optics for certain industrial applications (Sundar et al., 2003). 

SIMULANTS and REPLICAS: None that I know of -- for that matter, how might one create one?

| Top | Home |

R.V. Dietrich © 2015
Last update: 16 October 2006
web page created by Emmett Mason