GENERAL SUMMARY AND RECOMMENDATIONS. 



125 



Lastly, starfishes are probably the most serious of all invertebrate enemies. They 

 are present in very large numbers on some parts of the pearl banks. We have a 

 record that during the 1905 fishery, when the s.s. " Violet" was dredging for oysters 

 on the South Modragam Paar, between 200 and .300 specimens of Pentaceros lincki 

 and P. nodosus were brought up and destroyed each day. 



Further, we know these starfishes to be exceedingly voracious, tenacious of life, 

 active and fatal in their attacks on shell-fish. They seem to migrate from place to 

 place in search of food, and are found to congregate round the rich feeding ground 

 presented bv a new oyster bed. One of the commonest kinds of the larger starfishes 

 is Pentaceros lincki (fig. 16), known locally as the " Kondatchi Star," from its 



Fig. 16. Pentaceros lincki, de Bl., lying on a large pearl oyster, half natural size. 



abundance on that paar. When we examined this bank in March, 1902, it had a bed 

 of pearl oysters estimated at 5| millions. These had all gone by March, 1903, and it 

 is probable that their disappearance may be accounted for by the very large number 

 of starfishes present at that time. 



(III.) There are still three other causes of death in pearl oysters that require 

 mention, and may on occasion be serious, perhaps disastrous, viz. : 



(a) Overcrowding. The older oysters are sometimes buried in masses of younger 

 ones. The young are often piled together in such profusion as to interfere with each 

 other's nutrition and growth. Thinning out must and does take place. If we 

 don't do it, Nature does it for us. If it were done artificially, by transplanting some, 

 all or nearly all might be preserved ; if we leave it to be effected naturally by survival 

 of the fittest, the survivors may be very few indeed. 



(b) Disease, due to the invasion of parasites, either (1) worm parasites which are 



