The Quahog
Quahog
Chemistry
Under what range of salinities do
Quahogs thrive?
● the southern quahog seems to prefer the
oceanic water.
● they like to gather near inlets and in offshore
habitats
● grows rapidly under highly saline conditions
What is their shell made of and how do they
produce it?
● They secrete a calcium-based shell
material from an inner structure called the
mantle
● Create shell around themselves for
protection
● Shell grows as they mature
What effect does carbon in the
atmosphere have on shell formation?
Exterior of Clam
Lab Bench #4
clam is laying on its
right valve
anterior side
umbo
dorsal side
left valve
ventral side
hinge
posterior side
Interior of Clam
mantle
Lab Bench #4
adductor
muscles
foot
excurrent
siphon
gills
incurrent
siphon
Deep Interior of Clam
Lab Bench #4
anus
intestine
mouth/
digestive gland
Ecology: What do quahogs eat and
what eats them? Lab Bench #4
● Filter feeders who eat through siphons that they dig
into the mud
● Pick up tiny particles of plankton
● Predators include humans and a variety of
crustaceans and fish, including starfish, blue crabs,
horseshoe crabs, aquatic snails, skates, and rays
Ecology: Population Density Lab Bench #4
● lower water quality and higher population
density in areas closed to fishing in
Narragansett Bay
● causes lower reproduction capability and
gonadal cycle as compared to conditional
fishing areas
External
ventral
right valve
(bottom)
left valve (top)
anterior
posterior
umbo
hinge
dorsal
Internal
gills
anus
mouth
excurrent
siphon
foot
adductor muscle
mantle
intestine
incurrent siphon
Deep Internal
gills
excurrent
siphon
anus
mantle
adductor
muscle
incurrent
siphon
Geology
At what range of depths do quahogs thrive?
The Mercenaria Mercenaria (a local hard shell clam common called quahogs)
can be usually found at a depth of 10 meters. They use their muscular foot to
burrow deep into the sediment.
Virginia Pellerey
Elizabeth Blanchette
Katie Goglia
Geology
In what type of substrate (bottom material) are you likely to find
quahogs?
You are likely to find this kind of shell on mud/sand flats, typically near inlets and in
offshore habitats.
Virginia Pellerey
Elizabeth Blanchette
Katie Goglia
Julianna Risica
Ally Bush
Lauren Ranney
Finnian Duncan
Lab Bench 1: External
Hinge
Posterior
Anterior
Left Valve
(upper side)
Dorsal
Right Valve
(bottom side:
not shown)
Ventral
Umbo
Julianna Risica
Ally Bush
Lauren Ranney
Finnian Duncan
Lab Bench 1: Internal
Foot
Gills
Mantle
Adductor Muscles
Lab Bench 1: Internal Continued
Digestive Gland
Intestine
Incurrent Siphon
Julianna Risica
Ally Bush
Lauren Ranney
Finnian Duncan
Lab Bench 1: Research
Julianna Risica
Ally Bush
Lauren Ranney
Finnian Duncan
Reproduction of Quahogs
● Spawning Process
● Males release sperm through siphons
● Females release eggs through siphons
● Sperm and Eggs unite and Develop
Diet
● filter feeders
● suck up water through incurrent siphon and absorb
plankton, bacteria, oxygen
● filter water and waste products out of excurrent siphon
Lab Bench 1: Research Cont.
Julianna Risica
Ally Bush
Lauren Ranney
Finnian Duncan
Anatomy and Physiology
● Two shells made of calcium carbonate that the clam secretes
● Joint of the shells formed by hinge made up of intermeshing teeth
● The overall purpose of the shell: protect the interior of the clam
● Adductor muscles to close the shell to avoid predators or if water conditions are
bad
● Muscular foot (contains intestines, digestive glands, and gonads) can reach
outside the shell so that the clam can burrow
● Incurrent siphon brings water (oxygen and plankton) into the quahog
● Excurrent siphon: where the water (animal’s waste) exits
● Mantle: part of animal that forms shell (secretes calcium carbonate)
● Gills: obtain oxygen and food (cilia- tiny hair-like structures that creates a current
that moves water through the body)
Lab Bench 5: External
Dorsal
Hinge
Jessica Marabian
Deirdre Mcdonald
Hayley Page
Umbo
right
valve (on
top shell)
Posterior
Anterior
left valve
(on
bottom
shell)
Ventral
Lab Bench 5: Internal
Hayley Page
Jessica Marabian
Deirdre McDonald
Anterior
Adductor
Muscle
Digestive
gland
mouth
Posterior
adductor
muscle
anus
Excurrent
siphon
Incurrent
siphon
intestine
foot
gills (under
the foot)
mantle
Lab Bench 5: Harvesting Methods
Commercial quahoggers are not allowed to use mechanical methods (dredge or compressor) in
Bullrake
the bay. What methods can they use?
- Some use considerably large rakes called bullrakes
- Commercial businesses go out to the shoreline on single-handed boats
- Many work full time on small-skiffs
Are there size limits or seasonal limits? If so what are they?
- Yes there are size limits
-minimum size: 1 inch hinge width
What are conditional areas?
- The restrictions depend on what state one were to quahog
- One can only quahog from sunrises to sunset
- A licence is required
-In Rhode Island the management areas include: Potter, Point Judith, Ningret, Quonochontaug, Winnipuag, Ponds, Greenwich
Bay, Bristol Translplant, etc.
Lab Bench 6: Economics
Four Different Types of Quahogs: Kieran Maynard
● Little Neck- Smallest
● Cherry Stone- Little Larger
● Top Neck- Bigger than the Cherry Stone, also labeled count neck
clams
● Quahog- Biggest, also called chowder clams
Landing Numbers:
● Quahogs still in abundance
● Reduced fishing permits in areas
Economics: Zach and Kieran
Prices of Quahogs:
● Quahogs cost $2.00 per pound with 2-3
quahogs making a pound
● Quahogs bought in restaurants can be $6-25
External View: Joe Abilheira
Internal View: Joe Abilheira
Deep Internal View: Joe Abilheira