Mussel Collection & Dissection

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

External morphological differences Photo from McDaniel University Photo by Dr. YM Yakovlev M. californianus M. trossulus Photo from Ulster Museum M. galloprovincialis 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 cm500 cm 100 cm170 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

Hinge Anterior Posterior Dorsal Ventral Byssus ExcurrentSiphon IncurrentSiphon Posterior adductor muscle (shell closers) Mussel Dissection

Hinge Mantle edge (secretes shell and is sensory) Mantle surface (containing outgrowth of gonad) Incurrent and excurrent siphons Mussel Dissection

Mantle has now been lifted, but nothing is cut away Mantle edge Gill surface Gonad (proliferates into mantle which is otherwise thin and translucent) Cut adductor muscle Oral palp (one of two pairs) Mussel Dissection Mussel Dissection

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

Hinge Posterior adductor muscle (shell closer) Foot retractors Mantle attachment scar Tiny anterior adductor muscle (shell closer) Mussel Dissection

Posterior adductor & retractor muscles elongate, thin (California) Anterior adductor muscle on ventral edge (Bay) Mussel Dissection Anterior adductor muscle centered (California) Posterior adductor & retractor muscles shortened, wide (Bay) Muscle scars on shell distinguish Bay from California mussels

Tissue for extraction Cell density is high Cell density is high Connective tissue content is low Connective tissue content is low Mucus content is low Mucus content is low Therefore tissue breaks down easily and contains lots of DNA We use gill tissue for DNA extractions because…

Gills are used for respiration and sieving of food particles (e.g. phytoplankton) Gill Physiology 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 Food H 2 O In H 2 O Out

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

Continue dissection and identification of internal body parts Mussel dissection Identify gender of mussel Place gill tissue in tube and begin DNA extraction Locate gill and cut off one rice grain worth of tissue Cut posterior adductor muscle and open valves 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 Light’s Manual: Intertidal Invertebrates of the Central California Coast. Smith & Carlton, eds. University of California Press Living Invertebrates. by Pearse, Pearse, Buchsbaum, & Buchsbaum. Boxwood Press

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 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