THE SEA SHORE,
.
39
on
the surface.. It is extremely abundant in suitable
localities, such as the shore round Holy Island where a
population of 82,000 per acre has been estimated.
animal which might be easily takenfor a worm- is the reddish
Synapta, also found in sand, which is really a relativeof the
sea cucumbers.
Allied animals—in structure, not appear—
ance—are
the
burrowing sea urchins (Echinoàardæ'ur)
(Plate 20), to be dug near low—water mark, th0ugh, as we
shall see, they.are commoner=in deeper water. _'
It is on such sandy shores that the common shrimp
_
(Cramgon‘ vulgaris) is found, though it is difcult to see
owing to_ its sandy colour and its habit of covering itself
with sand, leaving only the long feelers exposed. .Wit—h it
are
a» variety of other crustaceans, notably the ghost—
—
shrimps (Mysids), smaller and even more difcult to see.
There are several kinds of crustaceans WhiCh cohstruct
burrows 0ften of great depth so that considerable industry
is needed _in digging them.
Several anerhones habitually
live buried in sand with only
mouth disc with the sur—
tentacles' exposed.
Where reefs of rbck
into the sand we frequently nd large colonies ,_of the
peculiar reef—building worm Sabellaria (Plate 18), a Creature.
which forms'a sandy. tube not in, but above, the sand, and
.
not singly but
great numbers altogether, SO that large
,_
reefs of harde‘néd sand are formed which. on
.
Will be found to be h0neÿcombed “with the tubes of the
worm's which construct them.
Various shes are common
in shallow water on sandy shores, being oCcasionallyleft
behindin pools by the retreat—ingtide ; of such are young
at-sh of various kinds and thé-sand-eel (Ammodyäes).
We may consider the associations found in mud and in
estuaries together because the months of rivers are -'.the
great site of mud deposition.
The fauna bears many
resemblances to that found on sand, with which_the mud
.
39
on
the surface.. It is extremely abundant in suitable
localities, such as the shore round Holy Island where a
population of 82,000 per acre has been estimated.
animal which might be easily takenfor a worm- is the reddish
Synapta, also found in sand, which is really a relativeof the
sea cucumbers.
Allied animals—in structure, not appear—
ance—are
the
burrowing sea urchins (Echinoàardæ'ur)
(Plate 20), to be dug near low—water mark, th0ugh, as we
shall see, they.are commoner=in deeper water. _'
It is on such sandy shores that the common shrimp
_
(Cramgon‘ vulgaris) is found, though it is difcult to see
owing to_ its sandy colour and its habit of covering itself
with sand, leaving only the long feelers exposed. .Wit—h it
are
a» variety of other crustaceans, notably the ghost—
—
shrimps (Mysids), smaller and even more difcult to see.
There are several kinds of crustaceans WhiCh cohstruct
burrows 0ften of great depth so that considerable industry
is needed _in digging them.
Several anerhones habitually
live buried in sand with only
mouth disc with the sur—
tentacles' exposed.
Where reefs of rbck
into the sand we frequently nd large colonies ,_of the
peculiar reef—building worm Sabellaria (Plate 18), a Creature.
which forms'a sandy. tube not in, but above, the sand, and
.
not singly but
great numbers altogether, SO that large
,_
reefs of harde‘néd sand are formed which. on
.
Will be found to be h0neÿcombed “with the tubes of the
worm's which construct them.
Various shes are common
in shallow water on sandy shores, being oCcasionallyleft
behindin pools by the retreat—ingtide ; of such are young
at-sh of various kinds and thé-sand-eel (Ammodyäes).
We may consider the associations found in mud and in
estuaries together because the months of rivers are -'.the
great site of mud deposition.
The fauna bears many
resemblances to that found on sand, with which_the mud