COLOUR AND PHOSPHORESCENCE
'
193
transparent massof small animals which unite one with
another to form ra hollow cylinder one end of Which is
closed, is found drifting about near the surface of the sea
and forms, a conspicuous member of the plankton in such
regions as
Mediterranean and tropical
Each
member of the colony has two light-producing glands and
,
the light they give ont is said to be red in some and-blue in
others, the whole colony when stimulated blazingwith
thousands of these tiny points of light Moseley, _one 'of
the
naturalists
on
the Challenger, states that, after a
,
Pÿrosoma more than four feet_long had been captured,
“
I wrote my name'with my nger on the surface of the
giant Pyrosoma as it lay on deck in a tub at night, and—my
_
’
name came out in a few Seconds in letters of re.”
.
At one time it was thought that luminous shes were
.
especially common in the deepest seas, regions of utter
—
darkness, the light being used to assist them in their Ÿ
search for food.
This is now known to be incorrect for,
.
though the sh living on the surface, such as the herring
or mackerel, never display luminescence, yet this power is
commonest in sh living at moderate depths, on the bottom
or in the intermediate regions.
Light organs are apparently
commonest in sh which live in the upper 500 metres of -
the warmer seas, although there are notable exceptions,
for example, a remarkable sh called Harpodon which
lives in rivers and estuaries in India and, When caught,
-
displays the most ‘ vivid phosphorescènce, and another
called Photoblepharon found in pobls of fresh water in
quarries and the craters of extinct'volcanoes in
The actual organs- vary a great deal in both structure and
position.
'
They 'may .be ”mere pits‘ and channels for the
'
producti0n of a lùminous slime, such as are found insome
"
of the deep-sea _Macruridàe, or they may
be complex -organs
like the natural latnps we have described in some of the
'
193
transparent massof small animals which unite one with
another to form ra hollow cylinder one end of Which is
closed, is found drifting about near the surface of the sea
and forms, a conspicuous member of the plankton in such
regions as
Mediterranean and tropical
Each
member of the colony has two light-producing glands and
,
the light they give ont is said to be red in some and-blue in
others, the whole colony when stimulated blazingwith
thousands of these tiny points of light Moseley, _one 'of
the
naturalists
on
the Challenger, states that, after a
,
Pÿrosoma more than four feet_long had been captured,
“
I wrote my name'with my nger on the surface of the
giant Pyrosoma as it lay on deck in a tub at night, and—my
_
’
name came out in a few Seconds in letters of re.”
.
At one time it was thought that luminous shes were
.
especially common in the deepest seas, regions of utter
—
darkness, the light being used to assist them in their Ÿ
search for food.
This is now known to be incorrect for,
.
though the sh living on the surface, such as the herring
or mackerel, never display luminescence, yet this power is
commonest in sh living at moderate depths, on the bottom
or in the intermediate regions.
Light organs are apparently
commonest in sh which live in the upper 500 metres of -
the warmer seas, although there are notable exceptions,
for example, a remarkable sh called Harpodon which
lives in rivers and estuaries in India and, When caught,
-
displays the most ‘ vivid phosphorescènce, and another
called Photoblepharon found in pobls of fresh water in
quarries and the craters of extinct'volcanoes in
The actual organs- vary a great deal in both structure and
position.
'
They 'may .be ”mere pits‘ and channels for the
'
producti0n of a lùminous slime, such as are found insome
"
of the deep-sea _Macruridàe, or they may
be complex -organs
like the natural latnps we have described in some of the