S2: “Know your mussel”S2: “Know your mussel”

Kingdom Animalia AnimaliaPhylum Mollusca ChordataClass Bivalvia MammaliaOrder Mytiloidea PrimatesFamily Mytilidae HominidaeGenus Mytilus HomoSpecies trossulus sapiens

Usually have:Usually have: Shell secreted by Shell secreted by mantlemantle

A head, foot, and A head, foot, and gillsgills

A specialized feeding A specialized feeding structure (radula)structure (radula)

A "trochophore" A "trochophore" larval stagelarval stage

Exceptions exist but Exceptions exist but the basic plan is the basic plan is unmistakableunmistakable

BIODIDAC, University of Ottawa

MollusksMollusks

Mollusca Mollusca

Photo by R. Willen

Gastropoda

Aplacophora

Bivalvia

Scaphopoda

Cephalopoda

PolyplacophoraMonoplacophora

www.whoi.edu/science/ B/aplacophora/

http://www.pmel.noaa.gov/vents/nemo/explorer/bio_gallery/biogallery1.html

http://http://www.biology.ucok.edu/www.biology.ucok.edu/AnimalBiology/Mollusca/AnimalBiology/Mollusca/

Scaphopoda.htmlScaphopoda.html

http://ourworld.compuserve.com/http://ourworld.compuserve.com/homepages/BMLSS/molluscs.htmhomepages/BMLSS/molluscs.htm

http://www.fish.washington.edu/http://www.fish.washington.edu/naturemapping/mollusks/mono/naturemapping/mollusks/mono/

6mono_int.html6mono_int.html

Incredible diversity of form and lifestyleIncredible diversity of form and lifestyle Second largest phylum (after Arthropoda) Second largest phylum (after Arthropoda) with 50,000 extant species and 35,000 with 50,000 extant species and 35,000 fossil speciesfossil species

http://www.mareco.org/rocky/mussel_relatives.html

http://www.marlin.ac.uk/learningzone/species/LZ_Ostedu.htm

BivalvesBivalves

Two shells joined Two shells joined by hingeby hinge

Laterally (left to Laterally (left to right) compressedright) compressed

Reduced head Reduced head lacking eyes & lacking eyes & tentaclestentacles

Primitively, a Primitively, a narrow foot narrow foot adapted for adapted for burrowingburrowing

Photos by Bill Austin,

Marine Ecology Centre

Photo by Keith Hiscock

MusselsMussels

The infamous invasive freshwater zebra mussel, Dreisenna polymorpha

The marine mussel, M. galloprovincialis

"Mussel" is a common name for "Mussel" is a common name for bivalves that attach using threads bivalves that attach using threads (byssus) (byssus)

Freshwater and marine mussels are Freshwater and marine mussels are not closely related (example of not closely related (example of convergent evolution)convergent evolution)

MusselsMussels

Adapted to hard surfacesAdapted to hard surfaces Byssal threads Byssal threads

Can move by detaching and Can move by detaching and reattaching threadsreattaching threads

Small and fingerlike foot Small and fingerlike foot forfor

Positioning new threadsPositioning new threads Crawling in small musselsCrawling in small mussels

Adapted for group livingAdapted for group living Anterior ends taperedAnterior ends tapered Posterior ends (with Posterior ends (with siphons) elevatedsiphons) elevated

Photo credit: MLML staff