﻿Verrill 
  — 
  Changes 
  in 
  the 
  colors 
  of 
  certain 
  fishes, 
  etc. 
  135 
  

  

  Art. 
  XIV. 
  — 
  Nocturnal 
  and 
  diurnal 
  changes 
  in 
  the 
  colors 
  of 
  

   certain 
  fishes 
  and 
  of 
  the 
  squid 
  (Loligo), 
  with 
  notes 
  on 
  their 
  

   sleeping 
  habits 
  /* 
  by 
  A. 
  E. 
  Yerrill. 
  

  

  While 
  investigating 
  the 
  nocturnal 
  habits 
  and 
  colors 
  of 
  

   some 
  of 
  our 
  native 
  marine 
  fishes, 
  in 
  1885 
  to 
  1887, 
  at 
  Wood's 
  

   Holl, 
  Mass., 
  in 
  the 
  laboratory 
  of 
  the 
  U. 
  S. 
  Fish 
  Commission, 
  

   of 
  which 
  I 
  had 
  charge 
  at 
  that 
  time, 
  I 
  made 
  the 
  unexpected 
  

   discovery 
  that 
  a 
  number 
  of 
  species 
  had 
  the 
  peculiar 
  habit 
  of 
  

   assuming, 
  while 
  sleeping, 
  a 
  style 
  of 
  coloration 
  quite 
  unlike 
  

   that 
  seen 
  in 
  the 
  daytime. 
  Numerous 
  other 
  duties 
  prevented 
  

   me 
  from 
  making 
  as 
  many 
  observations 
  of 
  this 
  kind 
  as 
  I 
  wished, 
  

   at 
  that 
  time, 
  nor 
  have 
  I 
  since 
  had 
  opportunities 
  to 
  continue 
  

   them. 
  Therefore 
  I 
  have 
  decided 
  to 
  publish 
  these 
  incomplete 
  

   observations, 
  with 
  the 
  hope 
  of 
  inducing 
  other 
  naturalists 
  to 
  

   continue 
  such 
  studies 
  in 
  some 
  of 
  the 
  various 
  zoological 
  stations 
  

   that 
  are 
  now 
  established. 
  

  

  Most 
  of 
  my 
  observations 
  were 
  made 
  late 
  at 
  night, 
  between 
  

   midnight 
  and 
  2 
  o'clock 
  A. 
  M., 
  when 
  everybody 
  else 
  had 
  retired. 
  

   The 
  gas 
  jets 
  near 
  the 
  aquaria 
  were 
  turned 
  down 
  so 
  low 
  as 
  to 
  

   give 
  barely 
  light 
  enough 
  to 
  distinguish 
  the 
  forms 
  and 
  colors 
  of 
  

   the 
  fishes. 
  Under 
  these 
  conditions, 
  by 
  using 
  great 
  care 
  not 
  

   to 
  cause 
  any 
  jar 
  of 
  the 
  floor, 
  nor 
  sudden 
  movements 
  of 
  any 
  

   kind, 
  I 
  succeeded 
  in 
  observing 
  many 
  species 
  asleep. 
  Most 
  

   fishes 
  sleep 
  very 
  lightly 
  and 
  are 
  aroused 
  by 
  almost 
  impercepti- 
  

   ble 
  vibrations 
  of 
  the 
  air 
  or 
  water. 
  Some 
  of 
  these 
  fishes 
  took 
  

   unexpected 
  attitudes 
  while 
  asleep. 
  

  

  In 
  many 
  cases 
  the 
  change 
  of 
  color 
  from 
  that 
  seen 
  while 
  

   awake, 
  or 
  in 
  the 
  daytime, 
  consisted 
  in 
  a 
  simple 
  increase 
  in 
  the 
  

   depth 
  or 
  intensity 
  of 
  the 
  colors, 
  the 
  pattern 
  of 
  colors 
  remain- 
  

   ing 
  the 
  same. 
  This 
  was 
  the 
  case 
  with 
  several 
  species 
  of 
  

   flounders. 
  Those 
  that 
  are 
  spotted 
  or 
  mottled 
  with 
  dark 
  pig- 
  

   ment 
  showed 
  their 
  markings 
  much 
  more 
  strongly, 
  or 
  in 
  

   greater 
  contrast 
  with 
  the 
  ground-color, 
  than 
  by 
  day. 
  Several 
  

   species 
  of 
  minnows 
  (Fundulus) 
  which 
  are 
  marked 
  either 
  with 
  

   longitudinal 
  or 
  transverse 
  dark 
  bands, 
  have 
  these 
  markings 
  

   more 
  decidedly 
  black 
  and 
  better 
  defined 
  than 
  by 
  day. 
  The 
  

   same 
  is 
  true 
  of 
  the 
  king-fish 
  {Menticirrus 
  nebulosus\ 
  in 
  which 
  

   there 
  are 
  obliquely 
  transverse 
  dark 
  stripes 
  that 
  come 
  out 
  more 
  

   strongly 
  at 
  night 
  than 
  by 
  day. 
  

  

  The 
  black 
  sea-bass 
  {Serranus 
  furvus) 
  and 
  the 
  sea-robins 
  

   {Prionotus 
  palmipes 
  and 
  P. 
  evolans) 
  presented 
  the 
  same 
  phe- 
  

   nomena. 
  Several 
  species 
  of 
  trout 
  (Salvelinus 
  fontinalis, 
  etc.) 
  

   were 
  observed 
  to 
  become 
  much 
  darker 
  at 
  night 
  than 
  in 
  the 
  

   daytime, 
  but 
  I 
  was 
  not 
  sure 
  that 
  any 
  of 
  those 
  observed 
  were 
  

   asleep 
  at 
  the 
  time. 
  

  

  * 
  Abstract 
  of 
  a 
  paper 
  read 
  before 
  the 
  American 
  Morphological 
  Society, 
  Dec. 
  30, 
  

   1896. 
  These 
  observations 
  were 
  also 
  communicated 
  to 
  the 
  Connecticut 
  Academy 
  

   of 
  Sciences, 
  in 
  1888, 
  but 
  were 
  not 
  published. 
  

  

  