100 
Fishery Bulletin 120(2) 
commercially, Hippospongia and Spongia (McClenachan, 
2008). Because of their soft and absorbent skeletons, spe- 
cies of these 2 genera had, and still have, a variety of uses 
(McClenachan, 2008). Before the appearance of synthetic 
sponges, natural sponges were used for personal hygiene, 
house and car cleaning, medical surgery, glazing pottery, 
cleaning industrial machinery and railroad equipment, 
tile and brick laying, and dressing leather and were used 
as gun swabs in the army and navy and in the manufac- 
ture of hats, soldiers’ helmets, and jewelry, among other 
things (Corfield, 1938; Stuart, 1948; Storr, 1964; 
McClenachan, 2008). Recently, the demand for commer- 
cially harvested sponges has extended beyond these 2 gen- 
era and has been driven primarily by the cosmetic, 
biomedical, and aquarium trades (Belarbi et al., 2003; 
Oronti et al., 2012; Mehbub et al., 2014). 
The work described in this contribution is the first 
attempt to fit to a sponge the standard version of the 
VBGF, an equation commonly used in marine biology 
and fishery research. There are several practical reasons 
to fit the VBGF to a sponge. First, since the publication 
of the classic text of Beverton and Holt (1957), the VBGF 
has been and remains part of the basic toolkit of fisher- 
ies science, mainly because of its versatility and realism. 
As such, its parameters are components of numerous mod- 
els used to understand and manage the exploitation of fish 
and invertebrate populations. Second, a standard growth 
curve should be useful for sponge mariculture, for exam- 
ple, to assess and compare the performance of individual 
sponges raised under different environmental conditions. 
The growth rates (in summer and winter) 
of 4 species of commercial sponges, the 
wool sponge, yellow sponge (Spongia 
barbara), glove sponge (S. cheiris), 
and grass sponge (S. graminea), from 
the Caribbean have been measured in 
the field, but those estimates do not 
include the full range of sponge sizes 
and ages (Butler et al., 2017). 
The third reason for fitting the VBGF 
to sponges is theoretical. The VBGF 
was derived from first-order physiologi- 
cal principles involving the interplay of 
surfaces and volumes leading to asymp- 
totic growth (see von Bertalanffy, 1938, 
1951; Pauly, 2019a, 2021a). It should 
therefore be enlightening to test if these 
principles, first derived for fish, also 
apply to sponges, the oldest multicellu- 
lar animal taxon. Also, this contribution 
might assist ecosystem modelers, who 
so far have usually neglected sponges 
(but see Opitz, 1996; Tudman, 2001; 
Butler, 2003; Pinkerton et al., 2008; 
Butler and Dolan, 2017). 
This contribution does not address the 
growth of encrusting or tubular sponges 
that, because of their laminar bodies, 
may not suffer from the respiratory 
constraints that are emphasized later herein. Rather, 
this study dealt with nearly sphere-shaped species, such 
as the wool sponge (Fig. 1). Our use of the wool sponge as 
an example is also pertinent because it is one of the most 
valuable and abundant commercially exploited species 
and therefore has been better studied than many other 
sponge species (Stevely et al., 1978; Witzell, 1998; Butler 
et al., 2017, 2018; Butler et al., 2021). 
Materials and methods 
Growth 
We fitted the VBGF to the empirical growth curve pub- 
lished by Storr (1964), which is based on wool sponges 
tagged in the upper Gulf of Mexico. Storr (1964) described 
the way he obtained growth data (mainly from sponges in 
grounds at Piney Point in Florida) as follows: 
“When the annual rates of increase between units of diam- 
eter were plotted, it was found that for growth beyond 
a diameter of 3-1/2 inches the growth factor could be 
expressed by the standard formula: 
y = AeBx, (1) 
where y = annual rate of increase—the growth factor; [and] 
x = radius of the sponge in inches at beginning of a 
year and A and B are constants, while e is the 
base of the Naperian logarithms. 
Sy TER EVERY USE 
wer THE TABLE 
Figure 1 
Images of a sheepswool sponge or wool sponge (Hippospongia lachne) that was 
18 cm in diameter and was collected in Florida by M. Butler on 18 September 
2021 and photographed by J. Butler: (A) shown in the wild in the Florida Keys; 
(B) side view, taken in the laboratory; (C) top view, taken in the laboratory; 
and (D) inside of the specimen, after horizontal sectioning in the laboratory. 
