Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-11-28
MINUTE MOLLUSKS
ADDED TO MUSEUM
1000, 900 Creatures Con-
tanned in Tiny ViaIs-Have
Weird Life Story.


added this week to the geological col
lection of the National Museum.
Approximately 1895, 900 of these an
finals were contained in mass of
three-Quarters of a cubic inch at the
bottom of q tiny glass vial. Another
$4,000 occupied half cubic inch III
. similar vial.
Yet they are the young of relatively
enormous creatures, 1t was explained by
DR.. Paul BartSch, curator Of molluSks,
and only an extraordinary death rate
among them makes it possible for the
great North American rivers to flow TO
the sea unhampered. And they have
one Of the weirdest life stories found In
animal creation.
The little walls contained the glo-
chidia of two fresh water mollusks OF
the Upper Mississippi Valley-tne
Lampsilis anodontoices and the Quad
rlla tuberculata. They are OF pearly
fresh water molluSks used in the ex-
banding pearl button industry and, to-
Rether with their close relations, are
one Of the greatest resources OF the
fresh waters Of Eastern North America,
says DR. Bartsch. The shells OF the
adult may be from 3 to 4 inches IN
diameter
Attaches TO Fish.
THESE creatures begin life, DR..
BartSch explained, when they hatch
from the eggs in the gills of the adult
rnollllsk. They are retained in the glilS
until they reach the so-called glocnlolal
stage represented by the present speci-
mems. Then they are cast forth into
the water to shift for themselves. Eacn
has already paired shell, like an aoult
clam or oyster.
But the little creature Is not prepared
e. kVnI
the world. The blind, helpless, micro
acopic organism lies, back down, on the
bottom. its shell open, and fine mu-
ceus thread arising from the body ana
nrotruding upward IN the water: a
Ash comes browsing along. The BODY
Of the fSh brushes against the thread:
which Immediately attaches itself ana
contracts, drawing upward the little
Vlochidium. When the creature comes
In contact with the fms or gills or scales
of the fish the shell snaps together,
firmly attaching the parasite to its host.
The whole happening Is too insignificant
to attract the attention OF the nsn.
Everything goes like clock-work.
But little spot Of irritation Is created
which then is acted upon by a juice
secreted by the glochidium. This eats
away the little cavity In the tissue OF
the fish in which the developing mollusk
secretes itself and dwellS in comfort
and safety until it has developed sum-
GENTLY to venture upon an independent
life of its own. At the end OF its para
site stage it drops out Of the body OF the
hsh.
Must Have Right Host.
The fish. DR.. Bartsch points out,
serves the microscopic creature not only
as q home, but a means Of transporta-
ton. In this way a species Is dis
tributed over a considerable area, lin
tied only by the habitat Of its host.
One of the most curious facts, Dr.:
Bartsch says, Is that each species OF
mollusk appears usually to attach itself
to only one variety of fish. DR.. Bartsch
himself demonstrated this with the
0lochidia Of the sand clans and gold
Ash. The little creatures climbed onto
the gills and fms Of the goldfish, but in
"a hours all had dropped OF. 1t just
wasn't their kind Of fsh. This, he says,
IN Of great importance to industry, be-
cause it makes 1t necessary In order TO
introduce O new variety OF molluSk IN
. region to have there already the sort
Of fish which 1t will accept as the host
Of its parasite days. It will die rather
than benefit by the hospitality OF the
wrong fish.
All this behavior, DR.. Bartsch points
out, cannot be interpreted as purposive
activity on the part of the individual
glochidium, which Is far from the level
OF anything akin to consciousness, but
u merely an example Of the marvellous
ly intricate mechanism Of nature. de-
veloped through evolution, for the de-
velopment and adaptation Of life.
Perish by the Billions.
During this process, he explained.
there are many miSsteps on the part
Of the glochidia-and 1t would be a
sad day for the world II this were not
the case. Actually they perish by the
billions Otherwise the adults with
their big shells soon would clog up all
the streams. which would be forced
out Of their channels over the country
side. and the whole economy Of nature
disrupted
The specimens were transferred to
the National Museum from the Bureau
Of Fisheries, to which DR.. Bartsch is
temporarily detailed, to take charge Of
the survey Of the pearl mussel industry
ordered by Congress in 1907. While
these varieties are of particular value
in the button industry, varieties with
similar life habits abound over the
North American continent. Some glo-
chidia are equipped with barbed hooks
--wicked-looking appliances under the
microscope-with which the glochidia
attach themselves to the FISH they Sc
lect as hosts.