Tedania gurjanovae — Bakus 
61 
One larva was observed swimming with the 
posterior pole directed forward. It was not 
unusual for natatory parenchymulae to pause 
for several minutes on the bottom of the glass 
finger bowl. 
There appeared to be no obvious negative 
or positive phototaxis. Levi (1956:119) noted 
that the larvae of Haliclona indistinct a ( Bower- 
bank) showed no particular taxis. Larvae of 
Lissodendoryx similis ( Ali, 1956:557) and 
Mycale syrinx (O. Schmidt) (Wilson, 1935: 
287 ) have shown negative phototaxis. Whether 
or not sensory cells are associated with this 
behavior is unknown at the present time (Jones, 
1962:13-14). Further observations on larval 
behavior are discussed by Jones ( 1962 : 1 3—14, 
49-50). Ali (loc. cit.) and Wilson (loc. cit.) 
both reported that some sponge larvae swim 
upwards then adhere to the water surface film 
and eventually die or disperse into scattered 
fragments and disintegrate. 
Four larvae were removed from their attach- 
ment to the parent and placed in a finger bowl 
of sea water to observe settling behavior. Two 
of the larvae were fixed to the bottom of the 
finger bowl 6 hr later; of the remaining larvae 
one appeared to be caught in the water surface 
film, the other attached to the bottom of the 
finger bowl after about the 7th hr. A few larvae 
appeared to have a slightly invaginated pos- 
terior pole just prior to fixation on the glass 
substratum (Fig. 3c). 
Larvae of Lissodendoryx similis (Ali, 1956: 
575) commence attachment to a substratum 
after about 40 hr; almost 24 hr of this period 
is spent swimming near the water surface. Sexual 
larvae of Esperella sordida (Bowerbank) (De- 
lage, 1892:370) swim for about 20 hr, whereas 
those of Mycale syrinx remain motile for 1 to 
3 days (Wilson, 1935:295). Some larvae of 
Mycale syrinx rotate on a substratum for as 
long as 10 days before fixation. The duration of 
the larval period of Halisarca metschnikovi 
Levi is 2 days, and that of Halisarca dujardini 
Johnston, less than 1 day (Levi, 1956:79). 
Asexual larvae of Esperella fhrexilis Wilson 
(Wilson, 1894:298) swim freely for 1 to 2 
days, whereas, those of Callyspongia diffusa 
(Ridley) ( Sivaramakrishnan, 1951:287) show 
natatory activities for only 6 to 8 hr. It is known 
that within a single species of marine animal 
the planktonic period varies considerably with 
temperature, the availability of food, and the 
proper substratum (Thorson, 1957:482; Moore, 
1958:314). Tedania gurjanovae apparently has 
a brief swimming period, at least under labora- 
tory conditions. 
In the present study, as a parenchymula larva 
attached to the glass substratum by the anterior 
end, the ciliary beat slackened in frequency and 
within 10 to 15 min all cilia appeared to be 
motionless. Approximately 30 min after fixation 
the typical larval habitus became completely 
disorganized. The mesenchymal cells collapsed 
from their original position and spread into a 
flat light-yellow circular plate measuring about 
600 /x in diameter (Fig. 3 d) . Segregation and 
spreading of cells continued. At 3 hr of age the 
<: 
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b 
Fig. 2. Spiculation of Tedania gurjanovae Koltun. a, Style, X 375; b, tornote, X 375; c, onychaete I, 
X 560; d, end of onychaete I, X 1260, note the echinations; e, onychaete II, X 375, note the comparatively 
finer echinations. 
