Spawning and Development of Some Hawaiian Marine Gastropods 
Jens Mathias Ostergaard * 2 
Many persons, at various marine biological 
stations situated throughout the world, have 
investigated the spawning habits and larva! 
development of marine gastropods. Some of 
the recorded observations date back to the 
middle part of the last century or earlier. 
Various methods have been employed to ob- 
tain the materials for study, but always the 
effort put forth has been well rewarded, for 
the field is exceedingly rich. It is noteworthy 
that the study of plankton alone has been 
able to throw much light on the metamor- 
phosis of the larvae of many species. This is 
a field of investigation that has an economic 
as well as an academic value, inasmuch as 
these minute planktonic larvae make a con- 
siderable contribution to the food supply of 
larger organisms, which in turn may serve 
as food for fishes that are of direct economic 
importance to man. 
The investigations recorded here are the 
first to be published from this area of the 
Pacific. All the studies were done at the 
Marine Biological Laboratory of the Univer- 
sity of Hawaii during the years 1920-1925, 
since which time nothing has been added. 
There are several reasons for this delay, the 
main one being the difficulty of publication. 
This required, among other things, much 
painstaking labor by a skilled person to adapt 
the many illustrations for reproduction. 
Many illustrations were required to clarify 
the text and to enable the reader to compare 
the corresponding stages of species of the 
same genus. All the figures were drawn in 
Contribution No. 2, Hawaii Marine Labora- 
tory. 
2 Department of Zoology and Entomology, Uni- 
versity of Hawaii. (Retired.) Manuscript received 
May, 1949. 
lead pencil by the author from observation 
under low power of the compound micro- 
scope. A micrometer scale was used so that 
measurements in fractions of millimeters 
could be made readily. 
All the species investigated were obtained 
in water not over 3 meters in depth, and most 
of the egg structures were deposited in the 
laboratory by isolated animals. When the 
spawns were obtained from the reefs, or else- 
where, careful checks had been made to as- 
certain their identity, which in most cases 
was later verified. No record of any species 
whose generic position was unknown has 
been included. Hence, discussion of a con- 
siderable number of additional species of the 
Nudibranchiata, whose systematic position 
has not yet been fully determined, awaits 
later publication. 
No histological sections of embryos and 
larvae were made, all notes being from ex- 
ternal observations. It will be noted that the 
ova of the various groups of gastropod mol- 
lusks discussed here were of the telolecithal 
type with holoblastic cleavage, of which the 
first two divisions were almost always equal, 
while the third division resulted in some 
blastomeres of minute size and with a small 
amount of yolk and other larger ones with 
much yolk. A trochophore stage of very short 
duration has been observed in some species, 
while a long veliger stage seems to be present 
in all. In no case has a metamorphosis from 
the veliger larva to the adult form been ob- 
served, nor even started, although a record 
was obtained of 21 days of free-swimming 
existence. 
Included in this publication are the results 
of the study of the development of 41 species 
which are placed in 28 genera belonging to 
C75] 
