A
ad hoc - to establish for a
specific purpose or situation
algae - a large group of primarily aquatic plants
that usually contain chlorophyll but lack the true roots, stems,
and leaves that are characteristic of more complex plants
anatomy - the structure of a plant or animal
anterior end - the shorter end of the shell as measured from
the umbo; also considered the front end
aquatic ecosystems - basic ecological unit composed
of living and non-living elements interacting in an aqueous environment
B
beak - the raised part of the
dorsal margin of the shell; also called the umbo
beak cavity - the depression or pocket on the inside of each
valve leading into the beak
beak sculpture - the raised loops, ridges, or bumps on the umbo
benthic - the bottom of a river, lake, or ocean
where the water meets the surface of the accumulated sediments
bivalve - a mollusk with a shell that consists
of two symmetrical valves
brail or crow foot drag bar - an approximately
8' foot long piece of wood or metal with chains hanging down. At
the end of each chain are several 4-pronged hooks with knobs on
each prong (like
small grappling hooks). As the bar is dragged along the bottom
of the river, mussels close on the hooks, thus allowing collection
of large numbers of mussels without diving.
brood pouch or marsupium - portion of female
mussel's gill where larvae develop into glochidia
byssal thread - one or more fibers secreted
from a gland in juvenile mussels. Allows attachment to a substrate
such
as large sand grains,
rocks, or even other mussels, thereby anchoring the mussel and
preventing it from being swept away by current. In zebra mussels,
the adults maintain their byssal threads which allows them to attach
to hard substrates (rocks, shells, boats, docks, etc.).
C
calcium carbonate - the primary
mineral that comprises the shell of a mollusk
channelization - the straightening and/or deepening of a river
channel
chevron - a V-shaped marking
clam - common name frequently used to refer to
certain freshwater bivalves (i.e., fingernail clams and
the Asiatic
clam). Differs from a mussel in that anterior and posterior
lateral and cardinal teeth are present
clammer or sheller - a person who harvests mussels compressed - flattened or pressed together laterally
concentric - having a common center
conglutinate - a number of glochidia bound together
with mucus
contaminant - an impurity in the environment
that may be toxic to sensitive organisms
cultured pearl - a pearl that was purposely developed
through human intervention
D
digestive tract - the series
of animal tissues that physically and chemically transform food
for assimilation
distal - away from the center or origin
diversity - the total number of species that
occupy an area dorsal - referring to the top part of the shell where the hinge
is located
E
ecosystem - an interdependent
group of plants and animals and the physical environment where they
exist
elliptical - having the form of an ellipse, or oval
elongate - long or extended
endangered - a species faced with the danger of extinction
extinct - a species that no longer exists
extirpated - a species that has been eliminated from a particular
area, but still exists somewhere else
exotic - from another part of the world; foreign
extinction - the processes that cause all members
of a species to die
extracted - removed from
F
fauna - a collective group animals,
particularly those of a certain region or time
G
glochidia - term for freshwater mussel larvae
that possess little or no automotive abilities that are ready to
be released from the
female
mussel
and usually attach
to a vertebrate host for continued life cycle development
glochidium - the larva of a freshwater mussel
(Superfamily Unionoidea) that generally lives as a temporary parasite
on a host fish;
a mussel larva that is microscopic, many species require a
fish as a host for development to a juvenile
growth lines - darkened lines on the surface
of the shell indicating periods of rest during growth
H
harvest - the take or consumption
of a renewable natural resource by humans
hermaphrodite - an animal or plant having both
male and female reproductive organs
hinge - the joint of the shell of a bivalve mollusk
host fish - one or more species of fish whose
tissues and body fluids meet the developmental needs of a particular
mussel species during its parasitic glochidial life stage
I
impoundment - a man-made reservoir
built from what was once part of a free-flowing river
inflated - swollen or expanded
interdentum - a flattened area between the pseudocardinal and
lateral teeth
introduced - brought in and established in a new place or surroundings
iridescent - exhibiting rainbow colors
J
juvenile -the life history stage after the larval
stage but before the adult stage
L
larvae - the embryonic life-cycle
stages that follow the fertilization of an egg of a metamorphic
animal
lateral teeth - the elongated teeth along the
hinge line of the shell of a bivalve mollusk
larva - the newly hatched, immature form of an animal that undergoes
metamorphosis, differing markedly in form or appearance from the
adult
left valve - the left half of the shell when the dorsal edge
or hinge is facing up and the anterior end is directed forward
(away from the collector)
ligament - a group of tough, fibrous tissues
that are attached to the shell of a bivalve mollusk and which expand
and contract to open and close the shell
locomotion - the self-propelled movement of an
organism from one location to another
M
mantle - a tissue lining the
inside of a mussel shell that encloses the viscera and secretes
new shell material from its edges for continued shell growth
marsupium - the portion of the gills of a female
mussel that contain glochidia
metamorphosis - a marked change in the form
or structure of an animal occurring after birth or hatching (verb.
metamorphose)
micrometer - a metric unit of linear measurement
equivalent to one-thousandth of a millimeter or one-millionth of
a meter, it is the common dimension used to measure the length
of
glochidia and juvenile mussels
midden - an accumulation of visually dead mussel
shells that suggests a prior living community
mollusk - a member of the phylum Mollusca, a
group of marine and freshwater invertebrates with soft tissues
that are protected by a hard shell composed of one or more parts
mortality - death
mussel - a marine or freshwater species with
an elongated shell; common name frequently used to refer to freshwater
mussels.
Differs from a clam in that either anterior or posterior lateral
teeth are present, but not both.
mussel bed - a dense, natural aggregation of
mussels which can support a diverse
variety of benthic fauna
N
nacre - the inner-most layer of
shell that often has a pearl-like appearance
naiad - a freshwater mussel
navigation channel - an artificially maintained
waterway that ensures a minimum water depth to allow unimpeded
passage for a variety of vessels
nuclei - the central core of an object that forms
the basis for its future development
nucleus - the center around which things are
formed. Beads made from the shell of freshwater mussels are used
as the center around which oysters lay nacre to form a cultured
pearl
O
oblong - having the shape of
or resembling a rectangle or ellipse
opalescent - exhibiting a milky
iridescence like that of an opal
ovate - egg-shaped
ovisac - membranous capsule containing glochidia
overexploitation - excessive consumption of a
renewable natural resource at a rate that cannot be maintained due
to a dwindling reproductive population
P
pallial line - a linear depression
on the inside of the shell
parasite - an organism that grows, feeds, and is sheltered on
or in a different organism (host) while contributing nothing to
the survival of the host
parasitic - characteristic of an organism that
grows, feeds, and is sheltered on or in a different organism (the
host) while contributing nothing to the survival of the host periostracum - the outside layer or covering of the shell
plankton - microscopic aquatic plants and animals
that depend chiefly upon currents for their movements
planktonic - exhibiting movements characteristic
of plankton plications - folds
pollywogging - wading in the water to find mussels
posterior end - the longer end of the shell as measured from
the umbo; also considered the back end; also the end with the siphons,
usually sticking above the stream bottom
posterior ridge - the ridge on the back half of the valve running
from the umbo to the posterior ventral edge
posterior slope - the area along the dorsal part of the shell
between the posterior ridges of the valves
propagate - human supervised plant or animal breeding
pseudocardinal teeth - the triangular, often
serrated, teeth located on the anterior-dorsal part of the shell
pustule - a bump or raised knob on the outside
surface of the shell
Q
quadrate - square
R
right valve - the right
half of the shell when the dorsal edge or hinge is facing up and
the anterior end is directed forward
(away from the collector)
S
secretion - a non-waste substance
that is derived and released from tissue cells for a specific purpose
sedentary - a lifestyle characterized by little
or no movement, thus remaining in one area
sediments - a complex mixture of materials transported
by flowing water that eventually settles and accumulates
serrated - notched or grooved
shell margin - the circumference of a valve outline when laid
flat; also known as the edge
sheller - see clammer sheen - a glistening brightness
siltation - deposition of fine mineral particles (silt) on the
beds of streams or lakes solid - thick or heavy spawn - to deposit sperm or eggs into the water species - a group of biologically distinct organisms
that are self-perpetuating
striated - marked with lines or grooves
substrate - soil on the river's bottom
sulcus - a shallow depression or furrow on the outside surface
of the shell
T
threatened - a species likely
to become endangered
toxic - harmful, poisonous, deadly
transform - metamorphosis in which a parasitic
glochidia matures physiologically and releases itself from the host
fish to live independently as a juvenile mussel
translocate - to displace or cause to move from
one location to another
truncate - having the end shortened or squared
off
tubercle - a small mineralized lump or nodule
that protrudes on the outer surface of the shell
U
umbo - the inflated dorsal part
of the shell; also called the beak
unionid - refers to freshwater
mussels in the order Unionoida. “Unio” is latin for
pearls.
V
valve - one of the two halves
of the shell of a bivalve mollusk
veligers - term for the planktonic larvae of
the zebra mussel
ventral - referring to the bottom edge of the shell |