Natural History : Water Pumping

Carmine coloured water released at the exhalent osculum of a Cloud Sponge

Almost all sponges pump water to obtain nutrients,  building blocks for the skeleton ( silicates in the case of glass sponges), and likely oxygen.  

 We have preliminary estimates of pumping rates for 4 small sponges,  3 in the lab and one in the field.    Rates were based  on the speed of  movement of carmine dyed water along a cm ruler for distances of 1-4 cm.  

   

Cloud Sponge “B” about 26 cm long x 17 cm wide by 10 cm. thick

All were fairly small sponges with a single large exhalent osculum. In the lab pumping rates for each sponge varied considerably from day to day and at times ceased totally.   Rates showed no obvious correlation with time in the lab,  water temperature, renewed water,  light,  time of day or night,  oxygen or vibrations. However,  this needs more detailed study.   Maximum rates for the sponges averaged 1cm/sec, 1.7cm/sec and  3cm/sec. This is comparable to the rates obtained in the field for the Boot Sponge, another glass sponge, by Gary Silver, a graduate student at the University of Victoria in the mid 1970s.

   

Video of  pumping in the field

Rates for the sponge in the field averaged 1.8 cm/sec.

The area of the osculum was calculated by drawing or photographing the osculum, photocopying the image onto graph paper with appropriate enlargement or reduction, and counting squares.  

The volume was calculated from the area x the distance.   It yielded values of 1.3 L/min; 1.7 L/min;  3.0 L/min for lab sponges; and 1.8 L/min in the field  

If sponges pumped continuously at this rate (which may well not be the case) we are looking at water volumes in the neighborhood of 2-4 tons/day

   

Pumping capacity is crudely based on the number of  flagellated chambers,  each operating as a mini-pump.   In the Cloud Sponge these chambers are essentially in one plane equivalent in area to the surface area of the sponge (not the volume as in some sponges).  

we can extrapolate still further to estimate rates in the largest measured sponge ( 3.4 meters long by 1.1 meters high by 0.5 meters wide).   This sponge has an area some 70 to 100 times that of the small test sponges  and IF it pumped with equivalent efficiency, would process 140 to 400 tons of water a day.

These are lots of “ifs” based on limited data but they, perhaps, give some idea of the significance of a population of these sponges in processing water.