﻿OYSTERS 
  AND 
  METHODS 
  OF 
  OYSTER-CULTURE. 
  289 
  

  

  menhaden, 
  the 
  alewife, 
  and 
  other 
  lish 
  equipped 
  with 
  delicate 
  sifting 
  

   devices 
  at 
  times 
  find 
  the 
  oyster 
  fry 
  of 
  some 
  importance 
  in 
  their 
  dietary. 
  

  

  After 
  the 
  attachment 
  of 
  the 
  spat 
  other 
  enemies, 
  active 
  and 
  passive, 
  

   wage 
  war 
  upon 
  it. 
  The 
  passive 
  enemies 
  affect 
  its 
  welfare 
  by 
  consum- 
  

   ing 
  its 
  food 
  or 
  by 
  smothering 
  it 
  beneath 
  their 
  own 
  more 
  active 
  growth. 
  

   Of 
  tiie 
  former 
  class, 
  mussels, 
  lingulas, 
  etc., 
  are 
  examples, 
  but 
  as 
  the 
  

   food 
  upon 
  an 
  oyster-bed 
  is 
  usually 
  sufiBcieut 
  for 
  all, 
  this 
  is 
  not 
  a 
  very 
  

   important 
  consideration, 
  particularly 
  as 
  in 
  the 
  end 
  an 
  equilibrium 
  is 
  

   established 
  through 
  the 
  intimate 
  reciprocity 
  which 
  exists 
  between 
  the 
  

   various 
  forms 
  of 
  life. 
  

  

  The 
  conditions 
  of 
  life 
  upon 
  an 
  oyster-bed 
  are 
  favorable 
  to 
  the 
  rapid 
  

   growth 
  of 
  dense 
  sponges, 
  mussels, 
  barnacles, 
  hydroids, 
  and 
  tube-build- 
  

   ing 
  worms, 
  which 
  establish 
  themselves 
  upon 
  tne 
  young 
  growth, 
  often 
  

   increase 
  more 
  rapidly 
  than 
  their 
  hosts, 
  and, 
  in 
  many 
  cases, 
  overgrow 
  

   them 
  to 
  such 
  an 
  extent 
  as 
  to 
  cut 
  off 
  the 
  supply 
  of 
  food 
  and 
  oxygen. 
  

   (Plate 
  XVII). 
  Aquatic 
  vegetation 
  sometimes 
  has 
  the 
  same 
  effect 
  when 
  

   its 
  growth 
  becomes 
  extensive. 
  Cert 
  lin 
  worms, 
  such 
  as 
  Serpula, 
  and 
  

   especially 
  Sabellaria 
  (plate 
  xv, 
  fig. 
  3), 
  often 
  build 
  their 
  tubes 
  of 
  lime 
  or 
  

   sand 
  so 
  rapidly 
  as 
  to 
  produce 
  dense 
  accumulations 
  upon 
  the 
  surface 
  

   of 
  the 
  shells, 
  thus 
  forming 
  a 
  nidus 
  for 
  the 
  collection 
  of 
  sand 
  and 
  mud. 
  

   Considerable 
  loss 
  has 
  at 
  times 
  resulted 
  from 
  the 
  suffocation 
  of 
  oysters 
  

   by 
  sponges, 
  worm 
  tubes, 
  and 
  vegetable 
  growths, 
  but 
  most 
  of 
  these 
  

   passive 
  forms 
  have 
  a 
  compensatory 
  use 
  in 
  the 
  food 
  which 
  tlieir 
  spores, 
  

   eggs, 
  and 
  young 
  furnish 
  to 
  the 
  oysters. 
  

  

  The 
  active 
  enemies 
  of 
  the 
  adult 
  oyster 
  are 
  those 
  which 
  injure 
  it 
  by 
  

   direct 
  attacks, 
  such 
  enemies 
  being 
  found 
  in 
  most 
  of 
  the 
  classes 
  of 
  

   zoological 
  life 
  having 
  aquatic 
  representatives. 
  

  

  Fishes 
  of 
  several 
  kinds 
  are 
  found 
  habitually 
  on 
  the 
  oyster-beds. 
  

   Most 
  of 
  these 
  offer 
  no 
  direct 
  injury 
  and 
  they 
  may 
  even 
  benefit 
  the 
  

   oyster 
  by 
  keeping 
  down 
  the 
  crowding 
  masses 
  of 
  hydroids 
  and 
  vegetable 
  

   life, 
  but 
  a 
  few 
  species, 
  of 
  which 
  the 
  drumflsh 
  is 
  apparently 
  the 
  most 
  

   destructive 
  upon 
  the 
  Atlantic 
  coast, 
  consume 
  considerable 
  quantities 
  

   of 
  oysters 
  as 
  food. 
  At 
  times 
  much 
  damage 
  has 
  thus 
  been 
  wrought 
  to 
  

   the 
  beds 
  in 
  the 
  vicinity 
  of 
  New 
  York 
  and 
  along 
  the 
  New 
  Jersey 
  coast. 
  

   In 
  ISan 
  Francisco 
  Bay 
  the 
  stingray 
  is 
  the 
  .most 
  feared 
  enemy 
  of 
  the 
  

   oyster, 
  and 
  schools 
  of 
  them 
  frequently 
  "clean 
  out" 
  the 
  beds 
  to 
  which 
  

   they 
  gain 
  access, 
  their 
  teeth 
  being 
  such 
  that 
  the 
  shells 
  are 
  crushed 
  into 
  

   fragments 
  in 
  their 
  grasp. 
  Some 
  of 
  the 
  skates 
  and 
  rays 
  on 
  the 
  eastern 
  

   coast 
  no 
  doubt 
  have 
  similar 
  habits, 
  but 
  they 
  do 
  not 
  appear 
  in 
  sufficient 
  

   numbers 
  to 
  cause 
  much 
  harm. 
  

  

  The 
  drills 
  are 
  the 
  most 
  destructive 
  enemies 
  of 
  the 
  oysters 
  in 
  the 
  

   Chesapeake 
  and 
  adjoining 
  regions, 
  as 
  well 
  as 
  upon 
  most 
  of 
  the 
  more 
  

   important 
  inshore 
  beds 
  northward. 
  There 
  are, 
  perhaps, 
  several 
  species, 
  

   but 
  the 
  most 
  destructive 
  is 
  the 
  form 
  known 
  to 
  naturalists 
  as 
  Uromlpinx 
  

   cinerca 
  (plate 
  xv, 
  fig. 
  1). 
  It 
  is 
  a 
  snail-like 
  mollusk, 
  which, 
  by 
  means 
  of 
  its 
  

   rasping 
  tongue, 
  drills 
  a 
  tiny 
  hole 
  in 
  the 
  shell 
  of 
  the 
  oyster, 
  through 
  which 
  

   it 
  extracts 
  the 
  soft 
  parts. 
  It 
  is 
  only 
  the 
  younger 
  oysters 
  which 
  are 
  thus 
  

  

  F. 
  C. 
  R. 
  1897—19 
  

  

  