Mussel Collection &
Dissection
http://hmsc.oregonstate.edu/projects/rocky/blue_mussels.jpg
Mytilus ecology

M. trossulus

M. galloprovinicialis
 Native to the North
Pacific (originally)
 Native to the
 Considered tolerant of:
 Considered tolerant of:
 Lower salinity
 Large tidal fluctuation
 Colder waters
Mediterranean Sea
 Higher salinity
 Small tidal fluctuation
 Warmer waters
Reference: Braby & Somero, 2005, Marine Biology
External morphological
differences
M. trossulus
Photo by Dr. YM Yakovlev
M. galloprovincialis
Photo from Ulster Museum
M. californianus
Photo from McDaniel University
Bay mussel
California mussel






Hatchet shape
Smooth texture
Periostracum* intact
*Thin chitinous covering that protects the shell
Elongate shape
Ribbed texture
Periostracum eroded
Random sampling

Mussels are collected at intervals along a
transect line

The intervals are drawn from a list of random
numbers
0 cm
500 cm
100 cm 170 cm
380 cm
Mussel collection
500 cm
0 cm
Quick Quiz
Why do we use random sampling?
a. So our data will accurately represent
the actual population
b. Because it’s a convenient way to
collect specimens
c. So we can be consistent with
previous researchers
d. All of the above
Quick Quiz
Why do we use random sampling?
a. So our data will accurately represent
the actual population
b. Because it’s a convenient way to
collect specimens
c. So we can be consistent with
previous researchers
d. All of the above
Quick Quiz
What is the proper way to transport
marine mussels?
a. In ethanol so they will be preserved
quickly
b. In freshwater to facilitate cleaning
c. In seawater so they will stay alive
d. In a plastic bag on ice
Quick Quiz
What is the proper way to transport
marine mussels?
a. In ethanol so they will be preserved
quickly
b. In freshwater to facilitate cleaning
c. In seawater so they will stay alive
d. In a plastic bag on ice
Quick Quiz
If the mussels will be sacrificed, why must
they be kept alive after collection?
a. It is the humane thing to do
b. To keep DNA intact
c. To allow cells to finish dividing
d. To make dissection easier
Quick Quiz
If the mussels will be sacrificed, why must
they be kept alive after collection?
a. It is the humane thing to do
b. To keep DNA intact
c. To allow cells to finish dividing
d. To make dissection easier
Mussel Dissection
Mussel Dissection
Posterior adductor muscle (shell closers)
Dorsal
Hinge
Excurrent
Siphon
Incurrent
Siphon
Anterior
Posterior
Byssus
Ventral
Mussel Dissection
Mantle edge (secretes shell
and is sensory)
Incurrent
and
excurrent
siphons
Mantle surface (containing
outgrowth of gonad)
Hinge
Mussel Dissection
Mantle has now been lifted, but nothing is cut away
Mantle edge
Cut adductor muscle
Gonad (proliferates
into mantle which
is otherwise thin
and translucent)
Gill surface
Oral palp
(one of two pairs)
Mussel Dissection
Right gill (filaments separated)
Visceral
mass
Left
gill
Byssus
Foot
Palp
Mussel Dissection
Foot retractors
Hinge
Tiny anterior adductor
muscle (shell closer)
Posterior adductor
muscle (shell closer)
Mantle attachment scar
Mussel Dissection
Muscle scars on shell distinguish Bay from
California mussels
Posterior adductor & retractor muscles
shortened, wide (Bay)
Anterior adductor
muscle centered
(California)
Posterior adductor & retractor
muscles elongate, thin (California)
Anterior adductor
muscle on ventral
edge (Bay)
Tissue for extraction
We use gill tissue for DNA extractions because…
 Cell density is high
 Connective tissue
content is low
 Mucus content is low
Therefore tissue
breaks down easily
and contains lots of
DNA
Gill Physiology
Gills are used for respiration and sieving of food
particles (e.g. phytoplankton)
 Siphons move water
in and out
 Small particles are
passed by the gills to
the mouth region
 Palps transfer food
from gill into the
mouth
H2O Out
H2O In
Food
Quick Quiz
Mussel gill tissue is optimal for DNA
extraction for all of the following reasons
EXCEPT:
a. low mucus content
b. high cell density
c. proximity to digestive tissue
d. low connective tissue content
Quick Quiz
Mussel gill tissue is optimal for DNA
extraction for all of the following reasons
EXCEPT:
a. low mucus content
b. high cell density
c. proximity to digestive tissue
d. low connective tissue content
Quick Quiz
Why do we measure the size of the mussels?
a. It’s a good thing to do
b. To see if different sexes are different sizes
c. To see if animals on docks are bigger
d. To see if there are correlations with species
Quick Quiz
Why do we measure the size of the mussels?
a. It’s a good thing to do
b. To see if different sexes are different sizes
c. To see if animals on docks are bigger
d. To see if there are correlations with species
Mussel dissection
Cut posterior adductor muscle
and open valves of mussel
Locate gill and cut off
one rice grain worth of tissue
Place gill tissue in tube and
begin DNA extraction
Continue dissection and
identification of internal body parts
Identify gender of mussel
Use muscle scar to confirm
not M. californianus
END
Resources

Mussel Collection Handout

Mussel Dissection Handout

Ecological gradients and mussels paper

Diversity of The Invertebrates: A Laboratory Manual
Pacific Coast Version. by James W. Nybakken.
William C. Brown Publications. 1995.

Light’s Manual: Intertidal Invertebrates of the Central
California Coast. Smith & Carlton, eds. University of
California Press. 1975.

Living Invertebrates. by Pearse, Pearse, Buchsbaum,
& Buchsbaum. Boxwood Press. 1987.
California State Chemistry Standards
Grade 8
6c. Living organisms have many different kinds of molecules
California State Biology Standards
Grade 7
5a. Plants and animals have levels of organization for structure
and function
5b. Organ systems function because of the contribution of
individual organs, tissues, and cells
Grades 9-12
9. As a result of the coordinated structures and functions of
organ systems, the internal environment of the [human] body
remains relatively stable (homeostatic) despite changes in the
outside environment
California State
Investigation and Experimentation
Standards
Grades 7, 9-12
a/b. Select and use appropriate tools and technology to perform
tests, collect data, analyze relationships, and display data
Grade 8
a. Plan and conduct a scientific investigation to test a hypothesis
National Standards
Grades 6-12
Content Standard A: Science as Inquiry
Content Standard C: Life Science
Content Standard E: Science and Technology