CHAPTER 15 

 Methods of Investigation 



The larger species of Pogonophora, possessing comparatively thick tubes, 

 are relatively easily found in the contents of the trawl, dredge, grab or 

 bottom corer. Sometimes, it is true, they may look like the tubes of sedentary 

 polychaetes at first glance, but attentive examination under the binocular 

 microscope soon reveals their true nature. The smaller very fine species, 

 especially some of the tinier Siboglinum, might escape detection, but they too 

 are recognizable in most cases upon examination under the higher powers of 

 binocular microscope from the characteristic rings and "segmentation" of the 

 tube. Tubes of pogonophores are rarely preserved whole; usually they are 

 broken or torn. It is therefore desirable to collect all the longest specimens 

 carefully, even if they are empty. Only in this way is it possible to gain some 

 idea of the overall length of the whole tube and details of the structure of the 

 various parts. Separate animals or parts of their bodies can sometimes be 

 found out of their tubes amongst the contents of the dredge or in the washings 

 from sifted soil. Such specimens are particularly valuable, since extraction of 

 the animal from the tube (particularly in some small species) is not always 

 successful. Epibionts (actinians, bryozoans, serpulids, Scalpellum and other 

 animals), frequently dwelling on the tubes of some pogonophores, should be 

 fixed without being detached from the tube, since they give one the oppor- 

 tunity of judging something of the way of life of the pogonophore. The 

 greatest scientific interest would attach to any collection showing stages of 

 embryological development in pogonophores. It is therefore well worth while 

 to put on one side any which possess eggs or embryos in the tube. In looking 

 for these tubes one should examine the material under the binocular by 

 transmitted light. 



Extraction of the animal from the tubes which have been collected can 

 only be accomplished with great difficulty. It can be carried out by using 

 magnifying spectacles or under the binocular microscope and demands much 

 patience and time. All the material to be dissected should be kept in bowls of 

 sea water cooled with ice, but even under these conditions the animals should 

 not be kept for more than l|-2 hr before fixation. [Siboglinum spp. have been 

 kept alive for six weeks or more in the cold room, but they are light-shy. It 

 seems probable that, as with many deep-sea creatures, the mere actinic rays 



145 



