SEA ANEMONES
HOW SEA ANEMONES ARE FORMED
The most beautiful of all the creatures which live in the sea are
undoubtedly the Sea Anemones, which are just like living flowers of
all sorts of lovely colours. But I do not know why they are called
sea “anemones,” for they are much more like asters, or dahlias, or
chrysanthemums.
These anemones are made in a very curious way. You will notice, as
you look down into a rock-pool, that their soft fleshy arms, or
“tentacles,” are all spread out like the petals of a flower. If you
touch them, however, they at once come closing in and disappear, so
that in two or three moments the creatures look like mere lumps of
coloured jelly. But if you wait for a little while they will push out
their tentacles again, and spread them just as before.
The fact is that the body of a sea anemone is a kind of double bag.
Suppose you take a paper bag, twist up the mouth, and push it
downwards, so that the sides of the bag surround it all the way round.
You will then have two bags, as it were, one inside the other, the
space between the two being filled with air. Now that is just the way
in which the body of a sea anemone is formed, with this difference,
that the space between the outer bag and the inner one is filled with
water. It forms, in fact, a kind of water-jacket.
Next, remember that all those spreading tentacles are really tubes,
like the fingers of a glove, closed at the top, but opening at the
bottom into this water-jacket. And remember also that the outer walls
of the body are formed of very strong muscles. So, you see, when
the anemone wants to spread its tentacles, all that it has to do is
to contract these muscles. The water is then squeezed up into the
tube-like tentacles, which of course expand. When it wants to close
them it relaxes the pressure, and the water flows out of the tubes
again and back into the water-jacket, so that they all come folding in.
The lower part of an anemone’s body is called the “foot,” and is really
a big and strong sucker, by means of which the animal clings so firmly
to the surface of a rock or a stone that it almost seems to be growing
out of it. But these creatures do not spend the whole of their lives
without moving, as oysters and barnacles do. Sometimes they will creep
slowly along over the surface of the rock, in order to find a more
comfortable situation, or one where they will have a better chance of
catching prey. And sometimes they will loose their hold of the rock
altogether, rise to the surface of the water, turn upside down, and
hollow their bodies in such a way that they form little boats, which
can float along over the waves for quite a long distance.
PLATE XLI
THE SMOOTH ANEMONE (1)
This is by far the commonest of all the sea anemones, and you may find
it in hundreds and thousands by going down among the rocks when the
tide is out, and looking into the pools. You are almost sure to see
that their rocky walls are dotted all over with lumps of brown or dark
green jelly, some only about as big as peas and some as large as plums.
These are Smooth Anemones, with their fleshy feelers, or “tentacles”
closed. And just here and there you may see one of them open, and you
will notice that all the way round the edge of its body, between the
roots of the tentacles, it has a row of little bead-like objects of
the most beautiful turquoise blue. For this reason the smooth anemone
is sometimes known as the “beadlet.”
You can easily keep these anemones in captivity, for they are very
hardy, and are no trouble at all to feed. Indeed, they will go without
any food at all for three or four months together, and seem all the
better for their long fast. But if you put a tiny dead crab, or a
shrimp, or a sandhopper, into the midst of their spreading arms, you
will see the tentacles close round it, and push it down into the mouth,
which lies just in the very middle. For about forty-eight hours the
animal will then remain closed up. But as soon as it has digested its
dinner out will come the tentacles again, bringing with them the empty
shell of the victim.
Every now and then, like other anemones, this animal changes its skin,
and when it leaves its position on the side of a rock-pool and crawls
to a new one, it nearly always leaves a cast skin behind it.
[Illustration: PLATE XLI
1. THE SMOOTH ANEMONE.
2. THE DAISY ANEMONE.]
PLATE XLI
THE DAISY ANEMONE (2)
This is not nearly such a common creature as the smooth anemone,
but you may sometimes find it in the rock-pools at low-water on our
southern and western coasts. It is pale greyish yellow in colour,
and has an odd way of altering its shape from time to time, so that
sometimes its body is long and slender, and sometimes it is short and
stout, while the disc may be long and narrow one day, and almost round
the next. You can always tell it at once, if you should happen to meet
with it, by looking at its fleshy feelers, or tentacles, which are
marked with rings of grey and white.
PLATE XLII
THE THICK-ARMED ANEMONE (1)
Where the coast is sandy and rocky too this anemone is often rather
common. Yet very few people ever see it, because it nearly always
fastens itself quite low down on the rocks which border the pools, so
that at least half of its body soon becomes covered up with sand.
Besides this, it has a great number of very tiny sucker-feet, not
unlike those of the starfishes and the sea urchins, and with these
it clings to tiny stones and bits of broken shell, which often quite
conceal its upper surface, so that one really cannot see the anemone
itself at all. But it is quite one of the very handsomest of all the
British sea anemones, for when it is fully grown it is over five inches
in width; and sometimes it is pearly white in colour, and sometimes it
is green, and sometimes it is purple and brown, and sometimes it is
crimson, while its tentacles are banded with scarlet and white. These
tentacles are rather stout in proportion to their length, and when they
are fully spread the animal looks very much like a cactus dahlia.
PLATE XLII
THE SNAKE-LOCKED ANEMONE (2)
This is also one of the prettiest of these very pretty creatures. But
it is not in the least like the thick-armed anemone, for instead of
having a broad, stout body it has a long slender one; and instead of
short, thick tentacles, like the petals of a dahlia, it has a bunch of
almost thread-like arms, which really rather remind one of little
white snakes. And when they are spread these long arms are hardly ever
still, but are always waving about in the water.
[Illustration: PLATE XLII
1. THE THICK-ARMED ANEMONE.
2. THE SNAKE-LOCKED ANEMONE.]
When the snake-locked anemone closes up, however, you would never know
it for the same creature, for it not only draws its long tentacles back
into its body and tucks them away out of sight, but contracts the body
itself until it is almost flat. Unless you looked very carefully at the
rock to which it was clinging you would never notice it at all.
This anemone is not a very common one, and is chiefly found on the
rocky coasts of Devonshire and Cornwall. In colour it is almost white.