The Relation of the form of a Sponge to its Currents

Abstract

All zoologists know that from the large holes, which we call oscula, on a sponge, an outgoing current may be detected in life. During several months in Naples I investigated this current, using litmus and carmine solutions, and carmine and indigo in suspension. I worked with two calcareous species of sponges, having oscula at the end of tubular prolongations, which reach the size and shape of a child’s thumb in the case of Leucaltis, and of a child’s finger in the case of Leucandra aspera (Text-fig. 1). The solutions were either placed on the surface of the sponge, to be sucked in by its currents (Text-fig. 2), or dropped by a pipette through an incision into the cloaca—the cavity of the tubular prolongation. In the latter case the time taken for the colour to be thrown out at the osculum, though liable to many corrections, afforded on the whole the most trustworthy determinations of oscular velocity: the cloaca being wider than the osculum, the observed cloacal velocity would be multiplied by 4, 5, or 6, as the case might be, to obtain the oscular velocity. A pretty method was arrived at accidentally (Text-fig. 3), when I found the coloured jet marked by dark beads or nodes, caused by my pulse shaking the pipette; the length between any two nodes, divided by three-quarters of a second, gives the core-velocity at that part of the jet.

CURRENT-INDUCED FLOW THROUGH THE SPONGE,HALICHONDRIA

“…The active rates reported by others are somewhat greater than that found here : Parker (1914), Bidder (1923), and Reiswig (1971) mention rates most of which are between 5 and 15 cm/sec. Still, the rate at which fluid passes the choanocytes, even when they are fully active, should be strongly dependent on the rate of movement of the medium.…”

“…But, of course, sponges are preeminently filterers, and perhaps the filtering function of the choanocytes requires continued flagellar action.As mentioned earlier, passive flow in sponges can result from the operation of several physical mechanisms, either singly or in combination. While the present data do not permit us to distinguish the particular contribution of each mechanism,Bidder's (1923) elaborate measurements on a specimen of Leiiconia (total flow, a is the radius and / the length of a pipe, and /JL is the viscosity of the medium) to his data yields a pressure drop of 67.2 dynes/cm 2 for his observed flow rate of 8.5 cm/sec at the osculum in otherwise still water. The first and third mechanisms for passive flow described in the Introduction depend on the operation of Bernoulli's principle.…”

“…The reduction in cross-section of the final common canal at the osculum has been interpreted as a further device to increase the excurrent velocity, and the oscular chimneys have been regarded as a means of increasing the distance between excurrent and incurrent openings. Both features presumably reduce the likelihood of recycling previously filtered water (Bidder, 1923;Leigh, 1971).…”

WATER TRANSPORT RATES OF THE TUNICATE CIONA INTESTINALIS

“…where q is flow volume (4.2 X 10'-cm 3 sec" 1 ), L is tube length exclusive of the "pump" (6.8 cm), /A is viscosity (1 X 10~ 2 dyne sec cm' 2 for sea water at 20), D is diameter (0.15 cm). The calculated internal pressure is 230 dyne cm~ 2 or <-~'2 mm H 2 O, which may be compared to values of 3-4 mm H 2 O for sponges (Parker, 1914;Bidder, 1923), and 2 mm H 2 O for Ascidia air a (Hecht, 1923).…”

Axial Filament of Silicious Sponge Spicules, Its Organic Components and Synthesis

“…controlling the synthesis and placement of these spicules. There is evidence that the growth pattern, while characteristic for a taxonomic group, is yet very sensitive to environmental factors related to current directions, velocity, and turbulence (Bidder, 1923). The production of spicules de novo is an intracellular secretory process which has received relatively little attention (Schroder, 1936;JoYgensen, 1 ( H4.…”