Additional Records of Hawaiian Platyctenea (Ctenophora ) 1 
Donald C Matthews and Sidney J. Townsley 2 
In a previous paper (Matthews, 1954:282) 
representative samples of all orders of Cte- 
nophora were reported for Hawaii. Of these, the 
platyctenids were represented by only two im- 
mature specimens of Coeloplana dubosequii col- 
lected on the reef of the Hawaii Marine Labora- 
tory on December 31, 1952. This small, pale, 
yellowish-green platyctenid has not been col- 
lected since, although the alga ( Hypnea nidifica) 
on which it was found has been periodically 
examined. Also, continuous examination of 
spines of the slate-pencil urchin, Heterocentrotus 
mamillatus (viz. Utinomi, 1961:116, pi. 58, no. 
9), has failed to reveal platyctenids, although 
Da wy doff (1938:161) reported having collected 
Coeloplana weilli on this urchin in the region 
of Ream (Gulf of Siam, Cambodia). It is rather 
ironical that, quite by chance, platyctenids were 
taken in 1961 on the spines of the black urchin, 
Echinothrix diadema, collected from the sandy 
bottom in about 10 m of water at the seaward 
edge of Waikiki reef. Again, in January, April, 
and May 1962, and in April 1963, platyctenids 
were taken on E. diadema at about the same 
depth, near Buoy No. 8, Kaneohe Bay, Oahu. 
Coeloplana willeyi Abbott, 1902 
Annotat. Zool. Japon, 4: 103-108 
Coeloplana willeyi Abbott, 1907 
Zool. Jahrb. Anat. Ont., 24:41-70 [full de- 
scription] 
Fortunately, as many as 50 platyctenids may 
crowd the spines of E. diadema in Hawaii. Thus, 
sufficient numbers are available from which a 
composite picture of this beautiful but extremely 
variable species can be made. Although their 
color is described as "scarlet or carmine red, 
fading toward the edges to a yellowish pink” 
1 Contribution No. 208, Hawaii Marine Laboratory, 
Honolulu, Hawaii. Manuscript received April 26, 1963. 
2 Department of Zoology, University of Hawaii, 
Honolulu. 
(Abbott, 1902:108), this characteristic in Ha- 
waiian specimens warrants further explanation. 
Distribution on spines seems color-correlated. 
Alternate purple and white rings characteristic 
of large spines of young E. diadema (vide 
Utinomi, 1961:113, pi. 57, no. 6) ultimately 
darken and fuse into black. Small C. willeyi, 
whose tentacular axes do not exceed ring widths, 
occur more frequently on dark rings; whereas 
large C. willeyi, whose tentacular axes exceed 
ring widths, occur more frequently spirally ar- 
ranged on dark rings. However, both small and 
large platyctenids seem distributed indiscrimi- 
nately over black spines of older urchins. Both 
small and large specimens appear lighter when 
removed to a light background. 
Background, however, is only one factor which 
affects color; another is their ever-changing 
shape. As described by Abbott (1907:46), cer- 
tain relaxed regions may flow in one direction 
like a thin film which, because of widely sepa- 
rated pigment granules, appears extremely light 
in contrast to certain contracted regions which 
appear dark. These "flows” may be limited to 
one side of the main (tentacular) axis, resulting 
in a highly asymmetrical, partially light and 
partially dark body, or they may proceed simul- 
taneously in all radii, resulting in a thin, almost 
circular, pinkish-yellow film. Although Abbott 
(1907:47) states: "about the periphery there is 
a series of white or yellowish-white spots or 
flecks of color . . .,” and Komai (1922:93) 
extends these to include the bases of the dorsal 
papillae, in the Hawaiian representatives of this 
species these spots or flecks are only weakly 
developed. Dependent, then, upon the above 
considerations C. willeyi in Hawaii may be 
described as deep purple, red, pink, or yellowish- 
white, and any one animal may reveal simul- 
taneously all of these various colors. There is, 
however, an overall tendency for the region 
along the tentacular axis to be darkest. The ven- 
tral surface is uniformly grayish-white. 
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