Mussel Collection & Dissection .

Mussel Collection & Mussel Collection & DissectionDissection

http://hmsc.oregonstate.edu/projects/rocky/blue_mussels.jpg

MytilusMytilus ecology 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 BiologyReference: Braby & Somero, 2005, Marine Biology

External morphological External morphological differencesdifferences

Photo from McDaniel UniversityPhoto from McDaniel UniversityPhoto by Dr. YM YakovlevPhoto by Dr. YM Yakovlev

M. californianusM. californianusM. trossulusM. 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 samplingRandom 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 collectionMussel collection

500 cm

0 cm

Quick QuizQuick Quiz

Why do we use random sampling?

a. So our data will accurately represent the actual populationb. Because it’s a convenient way to collect specimensc. So we can be consistent with previous researchersd. All of the above


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


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

HingeHinge

AnteriorAnteriorPosteriorPosterior

DorsalDorsal

VentralVentral

ByssusByssus

ExcurrentExcurrentSiphonSiphon

IncurrentIncurrentSiphonSiphon

Posterior adductor muscle (shell closers)Posterior adductor muscle (shell closers)

Mussel DissectionMussel Dissection

HingeHinge

Mantle edge (secretes shell Mantle edge (secretes shell and is sensory)and is sensory)

Mantle surface (containing Mantle surface (containing outgrowth of gonad)outgrowth of gonad)

Incurrent Incurrent and and excurrent excurrent siphonssiphons


Mantle has now been lifted, but nothing is cut awayMantle has now been lifted, but nothing is cut away

Mantle edgeMantle edge

Gill surfaceGill surface

Gonad (proliferates Gonad (proliferates into mantle which into mantle which is otherwise thin is otherwise thin and translucent)and translucent)

Cut adductor muscleCut adductor muscle

Oral palp Oral palp (one of two pairs)(one of two pairs)


ByssusByssus FootFoot PalpPalp

Visceral Visceral massmass

Right gill (filaments separated)Right gill (filaments separated)

Left Left

gillgill


HingeHinge

Posterior adductor Posterior adductor muscle (shell closer)muscle (shell closer)

Foot retractorsFoot retractors

Mantle attachment scarMantle attachment scarTiny anterior adductor Tiny anterior adductor muscle (shell closer)muscle (shell closer)


Posterior adductor & retractor Posterior adductor & retractor muscles elongate, thin (California)muscles elongate, thin (California)

Anterior adductor Anterior adductor muscle on ventral muscle on ventral edgeedge (Bay)(Bay)


Anterior adductor Anterior adductor muscle centered muscle centered (California)(California)

Posterior adductor & retractor muscles Posterior adductor & retractor muscles shortened, wideshortened, wide (Bay)(Bay)

Muscle scars on shell distinguish Bay from Muscle scars on shell distinguish Bay from California musselsCalifornia mussels

Tissue for extractionTissue for extraction

Cell density is highCell density is highConnective tissue Connective tissue

content is lowcontent is lowMucus content is lowMucus content is low

Therefore tissue Therefore tissue breaks down easily breaks down easily and contains lots of and contains lots of DNADNA

We use gill tissue for DNA extractions because…We use gill tissue for DNA extractions because…

Gills are used for respiration and sieving of food particles (e.g. phytoplankton)

Gill PhysiologyGill 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

H2O In

H2O Out


Mussel gill tissue is optimal for DNA extraction for all of the following reasons EXCEPT:

a. low mucus contentb. high cell densityc. proximity to digestive tissued. low connective tissue content


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 dissectionMussel 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

ResourcesResources 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 StandardsCalifornia State Chemistry Standards

Grade 8

6c. Living organisms have many different kinds of molecules

California State Biology StandardsCalifornia State Biology Standards

Grade 7

5a. Plants and animals have levels of organization for structure and function5b. 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 California State Investigation and ExperimentationInvestigation and Experimentation

StandardsStandards

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 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 .

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