The siphons or gastrozoids are large feeding 

 polyps, 15 mm to 20 mm long, rod-shaped tubes 

 of thick muscular wall. The largest part is the 

 stomach with the hepatic villi, and the outer 

 opening a muscular proboscis. The opening of 

 the mouth may be expanded in a kind of disc or 

 sucker, divided into several lobes. Haeckel's il- 

 lustrations (1888) presented the gastrozoids 

 with extremely large and expanded mouth. A 

 long single contractile tentacle is attached at 

 the base of each siphon. 



The tentacle arising from the base of each 

 gastrozoid consists of a long cylindrical tube 

 reaching to 80 mm or more than 100 mm long 

 when fully extended. The tentacles are long, 

 contractile, and branched along their whole 

 length, which is covered laterally by the single 

 branched tentilla. The tentilla are short, thin, 

 contractile filaments. Both tentacles and tentilla 

 are covered with nematocysts. The concave side 

 of each tentillum has sensitive papillae, and the 

 convex side is armed with cnidocysts. Twisted 

 masses of tentacles and tentilla form thick 

 bunches, difficult to disentangle. 



The gonodendra are attached by a short pe- 

 dicle to the periphery of the vesicular trunk, be- 

 tween the palpons and the siphons or gastrozoids. 

 The gonostyle is branched, and each branch has 

 at the end a gonopalponand a medusoid gyno- 

 phore (female gonophore) and below a bunch 

 of roundish androphores (male gonophores) 

 resembling altogether miniature clusters of 

 grapes. 



Epibuliidae float at the surface of the waters, 

 using the pneumatophore, swimming mainly by 

 the coordinated movements of the palpons, and 

 siphons. E. ritteriana adopts a vertical position 

 in the water, and the colony drifts and twists at 

 the surface of the sea, with the pneumatophore 

 at the top, floating at the surface, and the ten- 

 tacles shortened or extended deep into the waters 

 like fishing lines, with the gastrozoids actively 

 searching for food. 



It is possible that Cystalia monogastrica 

 Haeckel (1888) may be a juvenile stage of 

 Epibulia ritteriana. 



The scarcity of E. ritteriana is probably only 

 apparent, due to the factors previously explained. 

 Studies on the distribution of these highly preda- 

 tory animals would be of interest, when related 

 to the distribution of some fish larvae. These 

 Cystonectae may feed voraciously on epiplank- 

 tonic animals, mainly on those inhabiting the 

 uppermost layers of the epiplanktonic domain 

 (Clupeidae, Engraulidae, and other fish larvae), 

 which would suffer heavily under this active 

 predation. 



Acknowledgments 



I want to express my deep appreciation to Dr. 

 E. H. Ahlstrom, for his advice and encourage- 

 ment to prepare this work, for his interest and 

 time devoted in reading the manuscript, and for 

 his constructive suggestions. My appreciation 

 is also extended to D. Kramer for his valuable 

 editorial assistance. 



Literature Cited 



Brandt, J. F. 



1835. Polypus, Acalephas, Discophoras e Sipho- 



nophoras, nee non Echinodermata continens. 



Prodromus descriptionis animalium ab H. Mer- 



tensio is orbis terrarum circumnavigatione Ob- 



servarum 1:1-76. 

 Eysenhardt, K. W. 



1821. Ueber die Seeblasen. Nova Acta Leopold. 



Carol. 10:375-422. 

 Haeckel, E. 



1888. Report on the Siphonophorae collected by 



H.M.S. Challenger during the years 1873-76. Rep. 



Sci. Results Voyages H.M.S. Challenger, Zool. 



28, 380 p. 

 PiCKWELL, G. W., E. G. Barham, and J. W. Wilton. 



1964. Carbon monoxide production in a bathype- 

 lagic siphonophora. Science (Wash., D.C.) 144: 

 860-862. 



Totton, a. K., M. E. Bargmann. 



1965. A synopsis of siphonophora. Br. Mus. (Nat. 

 Hist.), Lond., 230 p. + 40 plates. 



A. Alvarino 



National Marine Fisheries Service 

 Southwest Fisheries Center 

 La Jolla, CA 92037 



509 



