Biology of Conus, I — Kohn 
177 
Conus spawn during about the same part of the 
year. The spawning season of most species for 
which more than one egg mass has been col- 
lected is rather extended over the months cited. 
Capsules containing viable eggs and embryos of 
C. rattus have been collected from February to 
August, of C. abbreviatus from March to July, 
and of C. pennaceus from May to August. 
The spawn of most species has been observed 
only rarely. However, 12 egg masses of Conus 
pennaceus were collected on nine occasions, all 
in the months of May, June, July, and August, 
suggesting that these months constitute the 
breeding season in this species. The preponder- 
ance of data for C. pennaceus (Table 1) is at- 
tributed partly to the fact that the egg masses 
of this species are readily identifiable, even in 
the absence of the parent from the collection 
site. Unlike other species, which attach each 
capsule to the substratum, C. pennaceus attaches 
only a few to the substratum, while the rest 
are attached to previously deposited capsules. 
Development. The eggs of Conus are typically 
white or pink, spherical or nearly so, and with- 
out a surrounding membrane. Polar bodies were 
not observed, but Ostergaard (1950) reported 
their occurrence in C. vexillum . 5 There are no 
nurse eggs; all or almost all eggs may develop to 
hatching in nature, but development was often 
arrested in a usually small but variable propor- 
tion of embryos in egg masses cultured in the 
laboratory. 
The number of eggs produced, egg diameter, 
length of development before hatching, and 
stage at hatching are summarized for 1 1 species 
of Conus from Hawaii in Table 2. Egg diameter 
was measured in 8 species, of which 7 ranged 
from 125 g to 225 g. In all of these species, the 
number of eggs was large, about 1,000-10,000 
per egg capsule and 15,000-210,000 per egg 
mass ( Table 2 ) . One species, C. pennaceus, has 
much larger eggs (460 g), of which consider- 
ably fewer are deposited (80/egg capsule; 
3,500/egg mass). 
As can be seen in Table 2, all the species 
with large numbers of small eggs hatch as free- 
swimming veligers, while C. pennaceus has vir- 
tually no pelagic stage, as was discussed in de- 
5 This species is referred to as C. sumatrensis Hwass 
by Ostergaard (1950). 
Fig. 15. Developmental stages of Conus vitulinus 
Hwass in Bruguiere, from the same egg mass as the 
capsule illustrated in Figure 14. a, Uncleaved egg; 
b, 2-cell stage; c, early blastula; d, trochophore-like 
stage; e, veliger, anterior-ventral view; f, veliger, la- 
teral view, e, Eye; f, foot; k, kidney; Ivl, left velar 
lobe; m, mouth; ot, otocyst; ps, pigment spot; rvl. 
right velar lobe. 
tail above. These data are in agreement with the 
correlations of large numbers of small eggs with 
long pelagic life and small numbers of large eggs 
with nonpelagic development first demonstrated 
by Thorson (1950, 1952) for mollusks and 
other benthic marine invertebrates. 
Salient features of development in four spe- 
cies of Conus are summarized in Table 3. The 
eggs are fertilized but have not yet undergone 
first cleavage when enclosed in the egg capsules. 
In the species studied, the trochophore stage is 
entered at 2-6 days, and the veliger stage at 6-10 
days, after spawning. Larvae hatch as veligers 
about 2 weeks after spawning. These observa- 
tions are in agreement with those of Ostergaard 
(1950), who also reported on development in 
