A turtle, waddling his solitary way along some watercourse, attracts
little attention apart from that aroused by his clumsy, grotesque shape;
yet few who look upon him are able to give offhand even a bare half-dozen
facts about the humble creature. Could they give any information at all,
it would probably be limited to two or three usages to which his body is
put--such as soup, mandolin picks, and combs.
In the northeastern part of our own country we may look for no fewer than
eight species of turtles which are semi-aquatic, living in or near ponds
and streams, while another, the well-known box tortoise, confines its
travels to the uplands and woods.
There are altogether about two hundred different kinds of turtles, and
they live in all except the very cold countries of the world. Australia
has the fewest and North and Central America the greatest number of
species. Evolutionists can tell us little or nothing of the origin of
these creatures, for as far back in geological ages as they are found
fossil (a matter of a little over ten million years), all are true
turtles, not half turtles and half something else. Crocodiles and
alligators, with their hard leathery coats, come as near to them as do any
living creatures, and when we see a huge snapping turtle come out of the
water and walk about on land, we cannot fail to be reminded of the fellow
with the armoured back.
Turtles are found on the sea and on land, the marine forms more properly
deserving the name of turtles; tortoises being those living on land or in
fresh water. We shall use the name turtle as significant of the whole
group. The most natural method of classifying these creatures is by the
way the head and neck are drawn back under the shell; whether the head is
turned to one side, or drawn straight back, bending the neck into the
letter S shape.
The skull of a turtle is massive, and some have thick, false roofs on top
of the usual brain box.
The "house" or shell of a turtle is made up of separate pieces of bone, a
central row along the back and others arranged around on both sides. These
are really pieces of the skin of the back changed to bone. Our ribs are
directly under the skin of the back, and if this skin should harden into a
bone-like substance, the ribs would lie flat against it, and this is the
case with the ribs of turtles. So when we marvel that the ribs of a turtle
are on the outside of its body, a second thought will show us that this is
just as true of us as it is of these reptiles.
This hardening of the skin has brought about some interesting changes in
the body of the turtle. In all the higher animals, from fishes up to man,
a backbone is of the greatest importance not only in carrying the nerves
and blood-vessels, but in supporting the entire body. In turtles alone,
the string of vertebrae is unnecessary, the shell giving all the support
needed. So, as Nature seldom allows unused tissues or organs to remain,
these bones along the back become, in many species, reduced to a mere
thread.
The pieces of bone or horn which go to make up the shell, although so
different in appearance from the skin, yet have the same life-processes.
Occasionally the shell moults or peels, the outer part coming off in great
flakes. Each piece grows by the addition of rings of horn at the joints,
and (like the rings of a tree) the age of turtles, except of very old
ones, can be estimated by the number of circles of horn on each piece. The
rings are very distinct in species which live in temperate climates. Here
they are compelled to hibernate during the winter, and this cessation of
growth marks the intervals between each ring. In tropical turtles the
rings are either absent or indistinct. It is to this mode of growth that
the spreading of the initials which are cut into the shell is due, just as
letters carved on the trunks of trees in time broaden and bulge outward.
The shell has the power of regeneration, and when a portion is crushed or
torn away the injured parts are gradually cast off, and from the
surrounding edges a new covering of horn grows out. One third of the
entire shell has been known to be thus replaced.
Although so slow in their locomotion and actions, turtles have
well-developed senses. They can see very distinctly, and the power of
smell is especially acute, certain turtles being very discriminating in
the matter of food. They are also very sensitive to touch, and will react
to the least tap on their shells. Their hearing, however, is more
imperfect, but as during the mating season they have tiny, piping voices,
this sense must be of some use.
Water tortoises can remain beneath the surface for hours and even days at
a time. In addition to the lungs there are two small sacs near the tail
which allow the animal to use the oxygen in the water as an aid to
breathing.
All turtles lay eggs, the shells of which are white and generally of a
parchment-like character. They are deposited in the ground or in the sand,
and hatch either by the warmth of the decaying vegetation or by the heat
of the sun. In temperate countries the eggs remain through the winter, and
the little turtles do not emerge until the spring. The eggs of turtles are
very good to eat, and the oil contained in them is put to many uses. In
all the countries which they inhabit, young turtles have a hard time of
it; for thousands of them are devoured by storks, alligators, and fishes.
Even old turtles have many enemies, not the least strange being jaguars,
which watch for them, turn them on their backs with a flip of the paw, and
eat them at leisure--on the half shell, as it were!
Leathery turtles--which live in the sea--have been reported weighing over
a thousand pounds! This species is very rare, and a curious circumstance
is that only very large adults and very small baby individuals have been
seen, the turtles of all intermediate growths keeping in the deep ocean
out of view.
Snapping turtles are among the fiercest creatures in the world. On leaving
the egg their first instinct is to open their mouths and bite at
something. They feed on almost anything, but when, in captivity they
sometimes refuse to eat, and have been known to go a year without food,
showing no apparent ill effects. One method which they employ in capturing
their food is interesting. A snapping turtle will lie quietly at the
bottom of a pond or lake, looking like an old water-soaked log with a
branch--its head and neck--at one end. From the tip of the tongue the
creature extrudes two small filaments of a pinkish colour which wriggle
about, bearing a perfect resemblance to the small round worms of which
fishes are so fond. Attracted by these, fishes swim up to grasp the
squirming objects and are engulfed by the cruel mouth of the angler.
Certain marine turtles have long-fringed appendages on the head and neck,
which, waving about, serve a similar purpose.
The edible terrapin has, in many places, become very rare; so that
thousands of them are kept and bred in enclosed areas, or "crawls," as
they are called. This species is noted for its curious disposition, and it
is often captured by being attracted by some unusual sound.
The tortoise-shell of commerce is obtained from the shell of the hawksbill
turtle, the plates of which, being very thin, are heated and welded
together until of the required thickness. The age to which turtles live
has often been exaggerated, but they are certainly the longest lived of
all living creatures. Individuals from the Galapagos Island are estimated
to be over four hundred years old. When, in a zoological garden, we see
one of these creatures and study his aged, aged look, as he slowly and
deliberately munches the cabbage which composes his food, we can well
believe that such a being saw the light of day before Columbus made his
memorable voyage.
He's his own landlord, his own tenant; stay
Long as he will, he dreads no Quarter Day.
Himself he boards and lodges; both invites
And feasts himself; sleeps with himself o'nights.
He spares the upholsterer trouble to procure
Chattels; himself is his own furniture,
Knock when you will,--he's sure to be at home.
Charles Lamb.