Mussel Collection & Dissection

Mussel Collection & Dissection http://hmsc.oregonstate.edu/projects/rocky/blue_mussels.jpg

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 Mytilus ecology Reference: Braby & Somero, 2005, Marine Biology

External morphological differences M. trossulus M. galloprovincialis M. californianus 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

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 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

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) Mantle surface (containing outgrowth of gonad) Incurrent and excurrent siphons Hinge

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)

Mussel Dissection Right gill (filaments separated) Visceral mass Left gill Foot Palp Byssus

Mussel Dissection Foot retractors Posterior adductor muscle (shell closer) Hinge Tiny anterior 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 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 Cutposterior adductor muscle and open valves of mussel Locategill 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

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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 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

National Standards Grades 6-12 Content Standard A: Science as Inquiry Content Standard C: Life Science Content Standard E: Science and Technology

Mussel Collection & Dissection