EFFECT ON ASCIDIANS AND MOLLUSKS.
_
'
43
thœe_ adherent to the skins of various whales), send off a
multitude of free—swimming young
which often cr0wd
the
inshore water, and extend far beyond before settling down
on every available surface. Many other instances of the pleni—
.tude of crustacean pelagic life, and its adaptation for the
nourishment of shes, might be given, but sufcient has been
’
_
cited to show that, besides the crustaceans of the bottom, those
frequenting the water itself must be considered.
‘
The ascidians or ‘ sea—squirts
’
of the bottom are occaSionætlly
brought up in the trawl 'attached to shells, stones, and sea—
weeds; and such forms, along with pieces of "sea—mat,’ are not
_
unfre_quent in the stomachs of cod and haddook. They are
'
usually sent overboard in a condition by 110 means unfavou1‘able
for existence, though it has to be stated that numerous pieces
_
Of adherent sea—mat are often brought to shore on the ground—
-
r0pe and meshes of the trawl from certain areas. The young
ascidians are free-swimming (tadpole-like), and escape inter—
ferenœ till they settle on shells, stones, and sea—weeds. An
'
interesting species in this group (OikopZewa or Appendiculaa)
is pelagic throughout life, and often occurs with its gelatinous
‘h0uses’ in dense multitudes in our inshore waters.
It lives
’
upon microscopic plants and similar structures in the water,
_
while the smaller shes and other forms prey on it.
-
-
'
The last group of the invertebrates liable to injury by the
trawl is that of the shell—shes and cuttle—shes (Mollusca).
In 1884: the opinion expressed was that, ‘amOngst the mollusks,
the. nudibranchs
a
little on deck, but the cuttle—shes
'
are more delicate, the majority being almost lifeless on removal
_
.from the net.‘
The horse—mussels are occasionally_actured,
but the whelks are uriinjured.’ With the exception of water—
.
logged wood bored by the Ship-worm, horse—mussels,
and whelks
_
of various kinds, the majority of the shells brought on board
were
old and empty, either covered with
_
growths of various
_
kinds, such as zoophytes, or harbouring star—shes
and annelids
‘
'
in their interstices.
As a rule, the horse—mussels were un'
injured, and were consigned in safety to the
water with
the
débris,
some
_
these—ÿ such delicate organisms .as the
SP&W1_Ï.0f the Norwegian whelk (Fusus 9207“veg£cus), With the
'
_
'
43
thœe_ adherent to the skins of various whales), send off a
multitude of free—swimming young
which often cr0wd
the
inshore water, and extend far beyond before settling down
on every available surface. Many other instances of the pleni—
.tude of crustacean pelagic life, and its adaptation for the
nourishment of shes, might be given, but sufcient has been
’
_
cited to show that, besides the crustaceans of the bottom, those
frequenting the water itself must be considered.
‘
The ascidians or ‘ sea—squirts
’
of the bottom are occaSionætlly
brought up in the trawl 'attached to shells, stones, and sea—
weeds; and such forms, along with pieces of "sea—mat,’ are not
_
unfre_quent in the stomachs of cod and haddook. They are
'
usually sent overboard in a condition by 110 means unfavou1‘able
for existence, though it has to be stated that numerous pieces
_
Of adherent sea—mat are often brought to shore on the ground—
-
r0pe and meshes of the trawl from certain areas. The young
ascidians are free-swimming (tadpole-like), and escape inter—
ferenœ till they settle on shells, stones, and sea—weeds. An
'
interesting species in this group (OikopZewa or Appendiculaa)
is pelagic throughout life, and often occurs with its gelatinous
‘h0uses’ in dense multitudes in our inshore waters.
It lives
’
upon microscopic plants and similar structures in the water,
_
while the smaller shes and other forms prey on it.
-
-
'
The last group of the invertebrates liable to injury by the
trawl is that of the shell—shes and cuttle—shes (Mollusca).
In 1884: the opinion expressed was that, ‘amOngst the mollusks,
the. nudibranchs
a
little on deck, but the cuttle—shes
'
are more delicate, the majority being almost lifeless on removal
_
.from the net.‘
The horse—mussels are occasionally_actured,
but the whelks are uriinjured.’ With the exception of water—
.
logged wood bored by the Ship-worm, horse—mussels,
and whelks
_
of various kinds, the majority of the shells brought on board
were
old and empty, either covered with
_
growths of various
_
kinds, such as zoophytes, or harbouring star—shes
and annelids
‘
'
in their interstices.
As a rule, the horse—mussels were un'
injured, and were consigned in safety to the
water with
the
débris,
some
_
these—ÿ such delicate organisms .as the
SP&W1_Ï.0f the Norwegian whelk (Fusus 9207“veg£cus), With the
'