68
'
THE SEAS
(Gon0plax), which has a reddish-br0wn rectangular shell '
and eyes on the ends of movable stalks.
'
A great host of molluscs nd a home ou the sea bottom,
‘_
the most conspicuous being large snails Such as the whelks,
‘
which includethe common Buccinum, the smooth—shelled
-
Fusus and Sipho, and Neptuna, with bold ridges running
_
‘
round its shell, the two latter being especially northern
beasts.
.The shell of these, and similar, animals is
’
quently covered with a moss-like growth which on examina—
tion proves to be a very interesting hydroid called Hydtactinia, which has three kinds of polyps, for feeding, reproduction and defence, respectively. Our largest sea slug, the
'
Triton (Tritonia), is frequently found at these depths ; it
is pale colour‘ed of various shades and browses on Dead"
-
men’s—ngers!
The boat—shell (Scaphander) ploughs
its
_—
Way through sand in the search for the small bivalves on
which it feeds.
Another strange beast ”living in sand is the
'
Elephant’s Tooth, our sole representative of a small but
'
distinct group of molluscs, which, as its name suggests,
has a long tapering shell, open at both ends.
Theempty
shells are frequently taken possession of by a small Sipunculoid warm
hermit crabs, which always live in
’
spiral—shells), which closes up the main opening except for a
small hole through Which it protrudes 'its long proboscis.
_
'
The varieties of bivalves are legion, from the large, very
thick—shelled
of the North Sea to the many
'
smaller kinds which are often almost incredibly abundant.
Thus on the DoggerBank one such, named'Spisula,- occurs
in patches often iii-ty miles by twe‘ntyand at a density of
anything fromone thousand to eight thousand to the square
,
metre, while another, called Mactra, is found in patches of
-
_
'
fteen to twenty miles in diameter‘and up to seven hundred
-
_per square metre…
Everywhere abundant are the many
-
different kinds ofScallops, varying in size from the large
,
_
'
THE SEAS
(Gon0plax), which has a reddish-br0wn rectangular shell '
and eyes on the ends of movable stalks.
'
A great host of molluscs nd a home ou the sea bottom,
‘_
the most conspicuous being large snails Such as the whelks,
‘
which includethe common Buccinum, the smooth—shelled
-
Fusus and Sipho, and Neptuna, with bold ridges running
_
‘
round its shell, the two latter being especially northern
beasts.
.The shell of these, and similar, animals is
’
quently covered with a moss-like growth which on examina—
tion proves to be a very interesting hydroid called Hydtactinia, which has three kinds of polyps, for feeding, reproduction and defence, respectively. Our largest sea slug, the
'
Triton (Tritonia), is frequently found at these depths ; it
is pale colour‘ed of various shades and browses on Dead"
-
men’s—ngers!
The boat—shell (Scaphander) ploughs
its
_—
Way through sand in the search for the small bivalves on
which it feeds.
Another strange beast ”living in sand is the
'
Elephant’s Tooth, our sole representative of a small but
'
distinct group of molluscs, which, as its name suggests,
has a long tapering shell, open at both ends.
Theempty
shells are frequently taken possession of by a small Sipunculoid warm
hermit crabs, which always live in
’
spiral—shells), which closes up the main opening except for a
small hole through Which it protrudes 'its long proboscis.
_
'
The varieties of bivalves are legion, from the large, very
thick—shelled
of the North Sea to the many
'
smaller kinds which are often almost incredibly abundant.
Thus on the DoggerBank one such, named'Spisula,- occurs
in patches often iii-ty miles by twe‘ntyand at a density of
anything fromone thousand to eight thousand to the square
,
metre, while another, called Mactra, is found in patches of
-
_
'
fteen to twenty miles in diameter‘and up to seven hundred
-
_per square metre…
Everywhere abundant are the many
-
different kinds ofScallops, varying in size from the large
,
_