, 1886-11-11
Teredo NavalIs
TIVE To TIMBER. \ PREVENTIVE
APPLICATION.
by James G. Swami

tested with myrladS OF minute cIed
Flres whose ravages on piles, vessels
bottoms, or any wood submerged in
the salt water, cause loss of thous-
ands Of dollars every year.
Prof. VprrIll says in his "lnverte-
brates Of Vineyard Sound
The Teredo navalis or ship worm
as it is commonly called, is not at
all related to the worms, but is Il
true mollusk, quite nearly allied in
many respects to the common long
clam, and to the Phoias, CT rock Oys-
ter. as they are mistakenly called.
Like these shells, the Teredo exca-
Yates its holes or burrows. merely for
its own protection, not for food. The
long clam bores it way into the
hard sandy bottom. The Phola bores
its way into soft rocks; but the Tere-
do selects wood in which to form its
holes. and when these have been ex-
cavated it lines them with tube of
shelly material. The holes are very
small at the surface of the wood,
where they were formed by the young
Teredos, but they gradually grow
lsrger a. they go deeper and deeper
into the wood until they somestimes
become from ten to twenty inches In
length and a half inch in diameter.
The Teredo on Puget Sound, exceed
ing in size anything found in the At
Iantic waters. The holes penetrate
the wood at first perpendicularly or
oblique, but if they enter the side of
the timbers or planks across the
grain, the burrows generally turn
horizontally in the direction Of the
grain short distance beneath the
surface, unless prevented by some
obstruction or by the presence OF
other Teredo tribes, for they never
cross the tubes of their companions
or interfere each other in any way,
and there is always a thin layer or
partition of wood left between the
adjacent tubes.
The Teredos grow very rapidly,
apparently attaining maturity IN one
season, and therefore, when abundant
they may completely destroy small
timbers in the course of four or five
months, and even the largest piles
may be destroyed by them in the
course of two or three years. When
removed from its tube the animal is
found to have a very long, slender,
smooth, soft, whitish body, tapering
somewhat toward the outer or pos
terror end. which has a muscular,
airculary, wrinkled collar by which
the animal is, when living, attached
to the inside of the shelly lining of
is tube. To the inside of this collar
two shelly plates, known as the pal
let's are attached by their slender
basal prolongations; their outer por-
lions are broad and fiat, and more or
less emarginate or two horned at the
end. These are so connected with
the muscles that when the animal
withdraws its tubes into the hole the
free ends of these pallets are made to
fold together and close the opening,
thus serving as an operculem to pro-
tect the soft tubes against enemies of
all kinds. Between the bases of the
pallets arise the siphonal tubes, which
are soft and retractile, united togeth-
sr for half their length or more, but
separate and diyerged beyond; they
are nearly equal, but the ventral or
branchial tube is perhaps a little
larger than the other, and is fringed
with few small papillae at the end
The tubes are white or yellowish,
speckIed with reddish brown. At the
anterior end of the body, and farth-
sr from the external opening of the
hole, is seen the small but elegantly
sculptuIed white bivalve shell. The
shell covers the mouth and palpi,
liver, foot, and other important or
gans. The foot is q short, stout,
muscular organ, broadly truncate or
rounded at the end, and appears to
be the organ by means of which the
excavation of the burrow is affected.
The shell is covered by delicate
epidermis, and probably does
not assist in rasping off the wood as
many have supposed. This species
produces its germ in May and proba
bly, through the greater part of the
summer. The eggs are exceedingly
numerous amounting to millions, and
they are retained III the gill cavity,
where they are fertilized and under
go the first stages of their develop,
ment. The embryos pass through
several curious phases during their
growth. In one of the early stages
they are covered with fine vibrating
ella, by means of which they can
swim; later they lose those ella and
develope rudimentary bivalve shell
which serve as organs for swimming;
IN this stage they swim actively about
IN the water; later long inguate
foot is developed by means of which
they can creep about and attach
themselves temporarily to solid OBJ
jects. These young Teredos, when
they finally locate upon the surface
of wood work and begin to make
their burrows, are not larger than
the head of pin, and consequently
their holes at first are very minute,
but owing to their rapid growth. the
holes quickly become larger and
deeper.
While the Terodo is boring its way
into the interior of the pile, another
destructive pest is gnawing and cut
ting away the outside so that the pile
Is completed y cut off as tree which
has been gnawed by bearer. This
minute terror is the sand flea OF am
phipod of which there are several
varieties, The apparently most de
structive kind is the boring amphi-
pod, chelura terebram. This is as
sociated with another marine insect
called the gribble Nimnoria) and are
found IN the submerged piles of old
wharves. The chelura excayates
timber not merely for the purpose of
concealment, but with the object of
it as food. The Limnoria
Lignorum works in narrow cylindri
cal burrows running deep into the
interior, while the excavations of che.
lura are considerably larger and
more oblique in their direction, SO
that the surface of the timber thus
by these destructive ami
mails is rapidly wayled away by the
action of the sea, the wood appearing
plowed up SO to speak, rather than
burrowed into.
Any one feeling interested in this
description, can easily ascertain its
correctness by examining any of the
piles at the end of Union wharf at
low tide, or at Point Hudson where