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<h4>LESSON IV</h4>
<h3>SOME STRANGE NURSERIES</h3>
<p>As a rule, nests or nurseries are unknown in the
world of fishes. They lay their eggs and leave them;
and the young ones have to fight their own battles,
in a sea full of fierce and hungry enemies. Indeed,
it often happens that a parent fish is eager to make a
meal of its own children!</p>
<p>The Codfish lays about nine million eggs! You
would hardly expect the female Codfish to make a
nursery for such a family! She would be much
worse off than the "old woman who lived in a shoe."
As a matter of fact, the eggs are laid in the open sea;
and the Cod shows no interest in them, but leaves
them to become food for many a roving enemy.</p>
<p>Those cousins of the Shark,--the Skate and the
Dog-fish,--are more careful of their eggs. Have you
ever found their empty eggs on the sea shore?
Children call them "mermaids' purses." But they
are more like little horny pillow-cases than purses.</p>
<p>When first laid, the Dog-fish's egg has a very long
string or <i>tendril</i> at each corner. As the fish lays the
egg, she winds these tendrils round and round a sea-plant;
thus the egg is fixed firmly until the young
one is ready to escape from within <SPAN href="#p49">(<i>see</i> p. 49)</SPAN>.</p>
<p>The Skate's egg is much the same, only there is
no tendril, but a curved hook at each corner. These
hooks, of course, serve as anchors to hold the egg:
no doubt they catch in weeds and stones. One fish,
you see, ties her eggs with strings, the other uses
anchors. These large "purse eggs" are like cradles,
and the baby Skates do not slip out of them until
they are quite ready to look after themselves in the
ocean.</p>
<p>There are fish in the sea which take great pains
to save their eggs and babies from harm; they
will even defend them at the risk of their own lives.
Of course these careful parents do not have huge
families, like the Cod. No; the fish that care for
their young have small families, but the babies
have a much better chance of living than the baby
Cod. It is one of Nature's wise laws.</p>
<p>Our common Stickleback--"Tiddler," or "Red-throat,"
as boys call him--builds a nest in ponds.
He has a seaside cousin, the fifteen-spined
Stickleback, who is also a nest-builder. This little
fish is fairly common round our coasts, living in
weedy pools by the shore, where it devours any small
creature unlucky enough to come near. It is about
six inches long, this sea Stickleback, with a long snout,
and its body is very thin near the tail.</p>
<p>To build his nest, this little fish chooses a quiet
corner, then gathers pieces of green and purple seaweed.
He takes the pieces in his mouth, pushing
them about until the shape is to his liking. Having
got his nursery to the right size and shape, the little
builder next fastens it together. How can he do this?
What mortar can he find in the sea? It is quite
simple. He uses threads, which come from his own
body. He swims round the nest, again and again;
and, each time, a thread is spun, binding the clump
of weed into a safe, tight nest for the eggs. When
the task is done there is a weed-nursery about the
size of your fist. Now all is ready for the eggs to
be laid by the female Stickleback. You would expect
them to be kept in a hole amid the nest, would
you not? Instead of that, they are tucked a few
here, a few there, in the weed.</p>
<p><SPAN href="images/img04L.jpg">
<ANTIMG align="right" alt="[Illustration: <i>Photo: A.F. Dauncey</i>. SKATE'S EGG CASE]"
src="images/img04.jpg"></SPAN>
Then the father Stickleback mounts guard. Woe
betide any small fish looking for a dinner of Stickleback
eggs! The gallant little sentry will rush at
him, with spines as stiff as fixed bayonets, ready to
do battle to the death. When the young are
hatched out he still keeps guard. They are not
allowed out of the nursery for some time. The watchful
parent forces them back if they try to wander
out into the perils of the shore-pool.</p>
<p>Let us look at another nest-builder--the Sand
Goby, or Spotted Goby, He is common enough in
the pools at low tide, but not easy to find. You can
look at him, yet not see him! For he takes the
same colour as the rocks and sands of his home.
Amid the glinting lights and shadows of his rock-pool,
with a background of sand, rock, and weed,
this little fish is nearly invisible. Of course it is a
dodge, and a useful one, to escape the eye of the
enemy!</p>
<p>Perhaps you will not think the Spotted Goby so
clever at nest-building as the Stickleback. He likes
to use a "ready-made" house, whereas the Stickleback
finds his own "bricks and mortar." In the
pools of the shore there is no lack of houses to let,
the empty homes of shell-fish are there in plenty.
So the little Goby, when nesting time comes, hunts
round for the empty shell of a Cockle lying with its
hollow side to the sand.</p>
<p>This shell is to be used as the roof for the nursery.
The Goby's next task is to make a hole beneath the
shell. He sets to work and, by scooping out the sand,
makes a hole about as large as a marble. To keep the
sand from tumbling in, he smears the hole with
slime, which soon binds hard like mortar. Now the
nursery is nearly ready; but a passage-way is made,
passing under the edge of the shell, and then, to
make things quite safe, the whole roof is covered with
sand: it then looks more like a bump in the sand
than a fish-nursery.</p>
<p>The female Goby enters the nest, and leaves her
eggs in it; and then the little father fish is left in
charge. He rests on the sand, near the entrance.
When the little ones appear, he seems to think he
has done his duty. So away, he swims, not staying,
like the father Stickleback, to guard the youngsters.
Again we see that the father, and not the mother,
is the builder and nurse.</p>
<br clear=all><SPAN name="plate3"></SPAN>
<center><SPAN href="images/img05L.jpg">
<ANTIMG alt="[Illustration: CORALS OF MANY KINDS.]" src="images/img05.jpg"></SPAN></center>
<p>That very strange creature, the Pipe-fish, has the
most peculiar nursery of all. He uses no building
material! No made-up nest of weed or sand for him!
No, he prefers to carry his eggs in his pocket. To be
more exact, there is a small pouch under his body,
and there the eggs are kept until they hatch. Meanwhile,
the Pipe-fish goes about his affairs in the pool
as if nothing particular had happened. You will
see more about this funny little fish when we come
to our lesson on "The Fish of our Rock-pools."</p>
<h4>EXERCISES</h4>
<p>1. What are the eggs of the Skate and the Dog-fish
like? 2. How does the Sea-stickleback build his nest?
3. Where would you find the Sand Goby, the Pipe-fish,
and the Sea-stickleback? 4. How does the Sand Goby
build its nest?</p>
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