﻿ECHIUROID 
  WORMS 
  OF 
  NORTH 
  PACIFIC 
  — 
  FISHER 
  279 
  

  

  Enemies. 
  — 
  Urechis 
  piohahly 
  attains 
  a 
  ripe 
  old 
  aj^o. 
  Five 
  spociinons 
  

   of 
  (lifToront 
  sizo, 
  kept 
  in 
  mud 
  in 
  the 
  laboratory 
  for 
  over 
  a 
  year, 
  appeat 
  

   not 
  to 
  have 
  p-own. 
  However, 
  as 
  their 
  food 
  is 
  prineipally 
  detritus, 
  and 
  

   as 
  natural 
  conditions 
  tire 
  necessary 
  to 
  keep 
  this 
  stirred 
  up 
  in 
  order 
  that 
  

   any 
  quantity 
  may 
  be 
  drawn 
  into 
  the 
  slime 
  net, 
  laboratory 
  <;rowtli 
  tests 
  

   are 
  not 
  convincini:. 
  Yet 
  what 
  mitrlit 
  be 
  temied 
  the 
  settled 
  habits 
  of 
  

   the 
  creature 
  ami 
  the 
  scarcity 
  of 
  very 
  small 
  specimens 
  point 
  stronjj:ly 
  

   toward 
  lonjicvity. 
  The 
  only 
  animal 
  known 
  to 
  prey 
  upon 
  them 
  is 
  the 
  

   stinj: 
  ray 
  (Myliohattis 
  califorjiicus 
  Gill), 
  which 
  can 
  dijj: 
  out 
  an 
  occa- 
  

   sional 
  Urecfii.'^. 
  In 
  tiie 
  ocean, 
  however, 
  small 
  worms 
  are 
  possibly 
  eaten 
  

   by 
  flatfishes, 
  which 
  repdarly 
  feed 
  upon 
  Listriolohus 
  pelodes. 
  As 
  

   already 
  noteil, 
  Dr. 
  Earle 
  H. 
  Myers 
  found 
  Urechis 
  in 
  the 
  stomach 
  of 
  

   small 
  sharks. 
  

  

  The 
  period 
  of 
  mortality 
  probably 
  comes 
  during 
  the 
  larval 
  stajre. 
  

   The 
  small 
  goby 
  {Clevelandia 
  ios) 
  is 
  extremelj' 
  numerous, 
  darting 
  here 
  

   and 
  there, 
  for 
  any 
  moving 
  particles. 
  These 
  fish 
  range 
  from 
  half 
  an 
  

   inch 
  to 
  IK 
  inches 
  in 
  length 
  and 
  often 
  devour 
  objects 
  so 
  small 
  as 
  to 
  be 
  

   invisible 
  to 
  the 
  observer. 
  On 
  one 
  occasion 
  400 
  of 
  these 
  little 
  gobies 
  

   were 
  netted 
  from 
  a 
  hole, 
  3 
  by 
  6 
  feet, 
  left 
  by 
  clam 
  diggers. 
  In 
  addition 
  

   the 
  tiny 
  Urechis 
  must 
  run 
  the 
  gauntlet 
  of 
  a 
  host 
  of 
  small 
  prcdaceous 
  

   crustaceaiLs, 
  annelids, 
  nemerteans, 
  and 
  mollusks 
  which 
  forage 
  on 
  the 
  

   surface 
  and 
  in 
  the 
  upper 
  layers 
  of 
  mud. 
  Once 
  established 
  in 
  a 
  biuTow 
  

   Urechis 
  is 
  relativel}' 
  safe. 
  

  

  Parasite. 
  — 
  I 
  have 
  found 
  rather 
  numerous 
  cestode 
  larvae 
  0.25-0.32 
  

   mm. 
  long 
  in 
  the 
  proximal 
  end 
  of 
  the 
  siphon 
  where 
  they 
  perhaps 
  cause 
  

   the 
  hernialike 
  swellings 
  of 
  the 
  siphon 
  wall 
  (pi. 
  35, 
  figs. 
  4, 
  4a, 
  5). 
  

   Probably 
  the 
  adult 
  is 
  to 
  be 
  found 
  in 
  the 
  sting 
  ray. 
  

  

  Spawning. 
  — 
  Stored 
  sex 
  products 
  are 
  found 
  in 
  the 
  ncphridia 
  through- 
  

   out 
  the 
  3'ear. 
  MacGinitie 
  (1938, 
  p. 
  208) 
  states 
  that 
  normal 
  spawning 
  

   takes 
  place 
  during 
  a 
  short 
  season, 
  usually 
  in 
  spring 
  or 
  at 
  the 
  begimiing 
  

   of 
  summer 
  as 
  the 
  temperature 
  of 
  the 
  water 
  rises. 
  One 
  male 
  which 
  he 
  

   kept 
  in 
  the 
  laboratory 
  for 
  two 
  or 
  three 
  years 
  spawned 
  on 
  May 
  24 
  and 
  

   25. 
  Just 
  prior 
  to 
  spawning 
  the 
  worm 
  came 
  nearly 
  to 
  the 
  opening 
  of 
  the 
  

   glass 
  tube 
  which 
  served 
  as 
  a 
  habitation. 
  Three 
  welts 
  were 
  thrown 
  around 
  

   the 
  body 
  so 
  that 
  the 
  circular 
  creases 
  were 
  just 
  anterior 
  to 
  each 
  of 
  the 
  

   three 
  pairs 
  of 
  gonopores, 
  and 
  the 
  gonopores 
  themselves 
  were 
  somewhat 
  

   protruded 
  and 
  turned 
  toward 
  the 
  anterior 
  end 
  of 
  the 
  body, 
  and, 
  

   therefore, 
  t^)war<l 
  the 
  opening 
  of 
  the 
  tube. 
  The 
  gonopores 
  became 
  

   quite 
  consj)icuoijs; 
  this 
  was 
  folh)wed 
  by 
  several 
  retching 
  movem(>nts, 
  

   as 
  if 
  the 
  aninud 
  were 
  attempting 
  to 
  n'giirgitate, 
  and 
  then 
  sperm 
  issued 
  

   in 
  a 
  stream 
  from 
  each 
  gonopore, 
  VVIu-n 
  the 
  sperm 
  ceased 
  to 
  bo 
  

   expelled, 
  the 
  animal 
  underwent 
  violent 
  jieristalsis, 
  the 
  waves 
  running 
  

   from 
  tin- 
  posterior 
  to 
  the 
  anterior 
  end, 
  causing 
  the 
  sperm 
  to 
  i)our 
  out 
  

   of 
  the 
  glass 
  tube. 
  The 
  retching, 
  followed 
  by 
  the 
  violent 
  antiperistalsis, 
  

   was 
  performed 
  three 
  distinct 
  times. 
  On 
  both 
  (hiys 
  after 
  s[)awning 
  the 
  

  

  B70329 
  — 
  40 
  5 
  

  

  