60 
PACIFIC SCIENCE, Vol. XVIII, January 1964 
TABLE 1 
Spicule Measurement (in g) of Tedania gurjanovae Koltun 
Author 
Bakus 
Specimen No. 
30 
Depth and Habitat 
192 m rock-shell bottom 
Style : 
Length 
Width 
296-324-335 
9-11-12 
Hastate Tornote : 
Length 
Width 
204-226-248 
5-6-7 
Onychaete I : 
Length 
Width 
40-75-91 
2. 2-2. 7-3. 5 
Onychaete II: 
Length 
Width 
142-168-265 
1.5-1. 7-1.8 
Bakus 
Koltun, 1958 
112 
2974 
110-128 m rock-shell bottom 
shell bottom 
318-340-373 
260-343 
10-12-13 
8-14 
222-236-252 
202-280 
4-6-7 
4-8 
58-69-89 
77-157 
2. 2-2. 6-3.0 
3-4 
150-174-265 
197-312 
1.2-1. 4-1. 6 
2 
LARVAL METAMORPHOSIS 
The dissection of a specimen of a sponge 
(lot No. 163) o m0> July 1959 revealed living 
embryos attached by the posterior end to the 
parental mesenchyme (Fig. 3a). Motile cilia 
were distributed over the entire surface except 
for the posterior pole. A minute region at the 
anterior end was very slightly pigmented. Both 
embryos and subsequently released larvae were 
cream colored. The larvae were typical paren- 
chymulae, roughly oblong in shape, and meas- 
ured from 500 /x long by 332 /x in mid-length 
diameter to 576 /x by 433 g. In released larvae 
the anterior pole had very short cilia; cilia were 
lacking on the posterior end (Fig. 3 b). Else- 
where the cilia were longer and of approximately 
equal dimensions. Several larvae contained one 
or two visible parental (?) spicules passing 
through their mesenchyme. This had no ap- 
parent effect on their swimming behavior. The 
presence of spicules in larvae of Demospongiae 
is common. Ali (1956:558-559), in a study on 
the development of Lissodendoryx similis Thiele, 
found that the larvae contained both micro- 
scleres and megascleres and in greater density 
than found in the adult. 
Larval spiculation was studied in preserved 
embryos. A mature embryo, ready to leave the 
parent sponge, contains several hundred ony- 
chaetes of both adult size groups, but the ma- 
jority are of the smaller category (I). More- 
over, there are about 25 to 35 conspicuously 
tapering and mildly echinated acanthostyles that 
measure about 120 /x in length by 10 /x in basal 
shaft diameter or 5 g in mid-shaft diameter. 
Both onychaetes and acanthostyles are concen- 
trated into a dense packet near one pole, though 
many onychaetes occur elsewhere throughout 
the larva. Since the larval acanthostyles ap- 
parently do not occur in the adult they may 
undergo further change to the stylote configura- 
tion. The late embryonic spicule distribution of 
Tedania gurjanovae looks something like that of 
the T. charcoti embryo as figured by Burton 
(1932:362, fig. 47L) . Burton (1932:361) re- 
ported that acanthostyles are the first spicules 
to appear in embryos of T. charcoti Topsent 
and that they become converted into smooth 
styles as development progresses. Further growth 
is indicated by a segregation of styles in a neat 
bundle at the "aboral pole of the embryo” and 
a rapid increase in numbers of rhaphides. Burton 
believes that rhaphides are probably the pro- 
totypes of adult onychaetes. 
The larvae swam with the anterior end di- 
rected forward and completed spiral gyrations. 
