resembles mucus. A variety of sulfide and sulfate minerals have 

 been identified by X-ray diffraction and corresponding mineral 

 grains can be located in mucus using a scanning electron 

 microscope equipped with an energy dispersive X-ray analyzer. The 

 quantitative contribution of mucus-aggregated minerals to the 

 mass of deposits forming in the palm worm's immediate environment 

 is not yet clear. The next stage of this investigation will be 

 directed toward acquiring quantitative data on mucus production 

 by palm worm populations and developing a means of identifying 

 traces of mucus within consolidated mineral deposits. 



Mucus produced by tube-dwelling palm worms has a somewhat 

 different fate in the vent environment. Palm worms that colonize 

 smoker chimneys use secreted mucus to aggregate mineral 

 particles into tubes which are attached to the sides of these 

 edifices (Fig. 7). How long such tubes remain inhabited has not 

 been established, although abandoned tubes are frequently 

 observed. Tube building palm worms appear to be the pioneer 

 colonizers of new smoker chimneys. A recent return visit to vents 

 on Axial Seamount has revealed year-old smoker chimneys to be 

 extensively covered in palm worm tubes (V. Tunnicliffe, personal 

 observation). Extensive coating of chimney walls by mucus- 

 cemented minerals may reduce wall porosity enough to effect 

 chimney growth and mineralization. Haymon (1983) has pointed out 

 the importance of wall porosity in the transition from sulfate 

 dominated to sulfide dominated stages in the growth of black 

 smoker chimneys. Repeat visits to vents at 13 N EPR have 

 revealed tube building activity by the pompeii worm to affect 

 development of smoker chimneys ( Fustec et al. 1987). The 

 influence of palm worm tube building on the growth and evolution 

 of smoker chimneys is presently being monitored in situ with a 

 time-lapse camera. Rates of anhydrite accumulation, sulfide 

 consolidation, palm worm colonization, and mucus cycling will be 

 studied over the course of a year. 



Trace Element And Heavy Metal Accumulation 



In addition to mineral particle aggregation, palm worm 

 mucus has two other geochemically interesting properties. Many 

 samples have been found to contain unusually high concentrations 

 of uranium, some in excess of 100 mg/kg (Juniper et al. 1986) 

 compared to the average crustal abundance of 3 mg/kg and vent 

 fluid and seawater concentrations of <0.5 to 3.00 mg/kg (Juniper 

 et al. 1986). Uranium is known to be adsorbed and complexed by 

 organic material under reducing or mild hydrothermal conditions. 

 Similar uranium concentrations have been observed in the 

 Galapagos hydrothermal mounds (Lalou et al. 1980). Another 

 unusual property of the mucus is that its muco-polysaccharide 

 matrix contains significant quantities of thiolic proteins that 

 preliminary analysis suggest are metal-binding proteins. The 

 exact nature of these proteins and the metals that they react 

 with remain to be determined. The interesting point is that the 



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