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PACIFIC SCIENCE, Vol. XIV, April I960 
phores, of the tentacles, 18 to 22 by 3 to 4 g, few 
(mostly at the tips); of the actinopharynx, 18 to 
20 by 3 to 3.5 g, few. Microbasic p-mastigo- 
phores, of the actinopharynx, 14 to 18 by 5 g, 
few; of the filaments, 13 to 22 by 4.5 to 6 /a, 
common. No nematocysts could be found in 
either the ectoderm or the entoderm of the 
column. Holotrichs are absent. 
DISCUSSION 
Especially noteworthy among the several dis- 
tinguishing features of Parazoanthus lucificum 
is its brilliant bioluminescence. E. N. Harvey 
(1952; 1955) gives no references to luminous 
Anthozoa excepting the Alcyonaria and none 
could be found in a rather thorough review of 
the literature on the Zoantharia. From this we 
in no way conclude that P. lucificum is unique 
in this respect, but we do believe that this is 
the first reported instance of bioluminescence 
for the genus Parazoanthus. Because of its bio- 
luminescence we have given to the species the 
Latin name lucificum, denoting "light producer.” 
FIG. 3- Transverse section of a macro- and micro- 
cneme of Parazoanthus lucificum . Only the encircling 
sinus is shown in the column mesogloea. Section taken 
from mid-column. Scale = .10 mm. 
The bioluminescence is restricted to the ten- 
tacles which flash both in the expanded and 
contracted state. The phenomenon is observed 
upon appropriate stimulation only. A sufficiently 
strong stimulus causes a large number of the 
polyps to light up. The glow is not steady at 
first but is characterized by intermittent flashes 
at the end of which time it continues steadily 
for as much as 10 seconds and then dims out. 
Because of the recurrent flashing, suggestive of 
nondirectional neural control, and negative 
smears for bacteria, it is our conclusion that the 
luminosity is intrinsic to the zoanthid. However, 
cells or granules that might be associated with 
the phenomenon were not observed. 
P. lucificum grows upon the gorgonian Muri- 
cea calif ornica. After the zoanthella larva settles 
on a living M. calif ornica the zoanthid rapidly 
and entirely replaces the soft parts of the gor- 
gonian. It appears that once the zoanthid is 
established the gorgonian has little or no defense 
against further encroachment. At the approach 
of the zoanthid’s coenenchyme the gorgonian’s 
tissues soften and slough off leaving exposed an 
area of bare skeleton which soon becomes oc- 
cupied by a zoanthid polyp. This process con- 
tinues until the gorgonian is completely re- 
moved from its skeleton. Although two other 
genera of gorgonians are found off Corona del 
Mar, P. lucificum does not grow on them. 
P. lucificum has been found growing only on 
Muricea calif ornica in spite of the fact that a 
second species, M. fruticosa, may in places grow 
side by side with the former. P. lucificum is the 
only known species of the genus to be regularly 
associated with a gorgonian. 
Morphologically and anatomically P. lucifcum 
is most similar to P. dichroicum Haddon and 
Shackleton, 1891, P. gracile (Lwowsky, 1913), 
and P. tunicans Duerden, 1900. It can, however, 
be distinguished from P. dichroicum by its yel- 
low color, lack of dichroism, fewer mesenteries, 
and larger polyps. Compared to P. gracile, P. 
lucificum has fewer mesenteries, larger polyps, 
and in the mesogloea lacks the peculiar cells 
with crystal-like inclusions (Lwowsky, 1913; 
Carlgren, 1934). The difference in the number 
of macrocnemes between P. lucificum and P. 
tunicans (to 17 in the former; to 16 in the lat- 
ter) is too slight to be of diagnostic value. While 
