26
THE B‘IOLOGY OF 'FISHES
and keep it in their air-bladder, whereas the shes that live
_'
in freshwater, with“ ready acCess to the surface and the air,
_
have no store of oxygen.
Some come to the surface, like
:
the mammalian porpoise, to get rid of the used—up gases
',
and take ifi air,’ others take in gulps and blow them out as
_
bubbles, and others again must have access to the surface ?
waters, where there is more oxygen, or they perish, even in
5
the water.
We can thus understand why many ;shes can hop or
:
squirm about on mud and land ; one or two even climb
branches of
80 long as they can retain moisture
to cover their gillS——and our lungs also require
they can breathe quite well in the air-. On a damp night
the Eel has been
miles over land, travelling
so fast in the graSS that the observers could._hatrdly keep up
with it. ; ]
—
—
'
;,
_
_,Ï
»
_f
"
It may-be that th1$
ability
_
:
thefreshwatershesBut1ftheyhveamongstthemudand
feeds; assomedotieybecometoelmgeandlazytobeveu:
—
,
the wd
.
arealsohvely,movmgabout w1thqu1ck intelligent
,
ments, andhere aga1nthey
a bountiful supply of oxygen
given
the'plant'life, We have but to compare the
?
behavi0ur of
or
Crested_ Blenny withj_that:Of
Cd nnquum to:noæ the dffn
:
.
îi.fi_:ïî‘îBut‘somé‘ 10£ th1shvehnesscomes ofcomsefmm “the
»
'
_
W1ththeJerkyshrimps,andhasl_ea111ttol&eep$till among
:
:
with the
}
:Çg
shtiïnp 131115 a
anjd picks up
:
* ”
'pùr{_suesäsrnaller âhes- than itself
,
in by the
ÎN_ot
=
_
much1ntelhgenceisrequ1redfor this kindof hunting; =._
_
'
:
’
“
::;The
between
maika are:pOpulated
"
gm.3ÏÏ-Yî by the smallsheswhich can remain fin.
and
'
betweenthe
mentioned, the
añd —1 the…
of.