54 
is clear that Rhombochirus shorter than about 
65 mm cannot be distinguished from the other 
genera by the disk length/pectoral length rela- 
tionship. 
Table 2 summarizes the length and host data 
for the specimens listed in Table 1. Where the 
host was identified only as "marlin” or "shark” 
no listing was made in Table 2. Also excluded 
are three echeneids removed from fish stomachs : 
a 46-mm P. lineatus and a 118-mm R. pallidus 
PACIFIC SCIENCE, Vol. XVIII, January 1964 
from Neothunnus macropterus, and a 56-mm 
R. osteochir from a "swordfish.” The term "free- 
living” denotes echeneids captured by plankton 
net, midwater trawl, or dipnet beneath a light. 
An aspect of echeneid biology which merits 
some discussion is the change in habit or host 
with growth. As shown by Strasburg (1959), 
attachment tends to be specific with respect to 
host and attachment site. For example, Phthei- 
richthys is either free-swimming or attached 
5a 
50 
40 
30 
20 
10 
^ 10 
20 
LiJ 30 — 
40 — 
50 
iXV 
o u 
o o 
o ° 
’CM, 
O ° 
O O o 
<9 o 
o 
o °P° 
o c ° 
* D V ^ * 
y v 7 
o Rhombochirus osteochir 
a Remora remora 
y Remoropsis pallidus 
* Remoropsis brachypterus 
□ Phtheirichthys lineatus 
50 
100 
150 
200 
250 
300 
350 
600 
650 
700 
STANDARD LENGTH (MM.) 
Fig. 1. Relative posterior extent of sucking disk and depressed pectoral fin for various echeneids. 
