Mussel Collection

1
Mussel Collection Dissection
http//hmsc.oregonstate.edu/projects/rocky/blue_mu
ssels.jpg
2
Mytilus ecology

• M. trossulus
• Native to the North Pacific (originally)
• Considered tolerant of
• Lower salinity
• Large tidal fluctuation
• Colder waters

• M. galloprovinicialis
• Native to the Mediterranean Sea
• Considered tolerant of
• Higher salinity
• Small tidal fluctuation
• Warmer waters

Reference Braby Somero, 2005, Marine Biology
3
External morphological differences
M. californianus
M. trossulus
M. galloprovincialis
Photo by Dr. YM Yakovlev
Photo from Ulster Museum
Photo from McDaniel University

• Bay mussel
• Hatchet shape
• Smooth texture
• Periostracum intact
• Thin chitinous covering that protects the shell

• California mussel
• Elongate shape
• Ribbed texture
• Periostracum eroded

4
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
5
Mussel collection
500 cm
0 cm
6
Quick Quiz

• Why do we use random sampling?
• a. So our data will accurately represent the
  actual population
• b. Because its a convenient way to collect
  specimens
• c. So we can be consistent with previous
  researchers
• d. All of the above

7
Quick Quiz

• Why do we use random sampling?
• a. So our data will accurately represent the
  actual population
• b. Because its a convenient way to collect
  specimens
• c. So we can be consistent with previous
  researchers
• d. All of the above

8
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

9
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

10
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

11
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

12

• Mussel Dissection

13
Mussel Dissection
Posterior adductor muscle (shell closers)
Dorsal
Hinge
Excurrent Siphon
Incurrent Siphon
Anterior
Posterior
Byssus
Ventral
14
Mussel Dissection
Mantle edge (secretes shell and is sensory)
Mantle surface (containing outgrowth of gonad)
Incurrent and excurrent siphons
Hinge
15
Mussel Dissection
Mantle has now been lifted, but nothing is cut
away
Mantle edge
Gonad (proliferates into mantle which is
otherwise thin and translucent)
Cut adductor muscle
Gill surface
Oral palp (one of two pairs)
16
Mussel Dissection
Right gill (filaments separated)
Visceral mass
Left gill
Foot
Palp
Byssus
17
Mussel Dissection
Foot retractors
Posterior adductor muscle (shell closer)
Hinge
Tiny anterior adductor muscle (shell closer)
Mantle attachment scar
18
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)
19
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

20
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
21
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

22
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

23
Quick Quiz

• Why do we measure the size of the mussels?
• a. Its 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

24
Quick Quiz

• Why do we measure the size of the mussels?
• a. Its 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

25
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
26

• END

27
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.
• Lights 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.

28
California State Chemistry Standards

• Grade 8
• 6c. Living organisms have many different kinds
  of molecules

29
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

30
California State Investigation and
ExperimentationStandards

• 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

31
National Standards

• Grades 6-12
• Content Standard A Science as Inquiry
•  
• Content Standard C Life Science
• Content Standard E Science and Technology