~ scallops are commercially important. All members of the superfanLily Pectinaceaare considered scallops. There have been aplJ'roximately 7,000 species and subspecies named within the superfanlily Pectinacea. (This is however, greatly in need of revision). Scallops are found throughout the marllLe environment, from the tropics to the poles, from the intertidal zone down to 3,000 meters, ttlough most are found inshore. The Pectinidae are believed to have evolved around 230 million years ago! A scallop is a member of the class Bivalvia. In order to be a member of the class bivalvia an organism must be laterally compressed and it must have two valves or shells connected by a dorsal hinge. The two shells completely enclose the body. Other members of the class Bivalvia are clams, oysters and mussels. The class Bivalvia falls under a larger classification which contains other classes as well. This is known as a phylum. The phylum to which the bivalvia belong is known as Mollusca. The phylum Mollusca are some of the most well known invertebrates, or organisms without backbones. Members of this phyla are found in the sea, fresh water and on land. Molluscs have been around since the precambrian era, over 500 hundred million years ago! They are distinguished by the presence of a muscular foot, gills and a calcareous shell secreted by an underlying integument called the mantle. Some well-known members of this phyllum include scallops snails, squid and octopods. All scallops fall within the family Pectinidae and there are about 400 known extant species within the family. Only some 7
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scallops are commerciallyimportant. All members of thesuperfanLily Pectinacea areconsidered scallops. There havebeen aplJ'roximately 7,000 speciesand subspecies named within thesuperfanlily Pectinacea. (This ishowever, greatly in need ofrevision).
Scallops are found throughoutthe marllLe environment, from thetropics to the poles, from theintertidal zone down to 3,000meters, ttlough most are foundinshore. The Pectinidae are believedto have evolved around 230 millionyears ago!
A scallop is a member of theclass Bivalvia. In order to be amember of the class bivalvia anorganism must be laterallycompressed and it must have twovalves or shells connected by adorsal hinge. The two shellscompletely enclose the body.
Other members of the classBivalvia are clams, oysters andmussels. The class Bivalvia fallsunder a larger classification whichcontains other classes as well. Thisis known as a phylum. The phylumto which the bivalvia belong isknown as Mollusca. The phylumMollusca are some of the most wellknown invertebrates, or organismswithout backbones. Members ofthis phyla are found in the sea,fresh water and on land.
Molluscs have been aroundsince the precambrian era, over500 hundred million years ago! Theyare distinguished by the presenceof a muscular foot, gills and acalcareous shell secreted by anunderlying integument called themantle. Some well-known membersof this phyllum include scallopssnails, squid and octopods.
All scallops fall within thefamily Pectinidae and there areabout 400 known extant specieswithin the family. Only some
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Kingdom (General)Animalia
you HomosapienAmerican oyster Crassodoma VirinicaOctopus Octopus vulgarisRock scallop Crossodoma GiganteaBay scallop Argopectine irrandiansCalico scallop A. Gibbus
There are 3 spe,,::ies of scallops which arecommercially harvested on the eastern coast ofthe United StatE~s; these are:Araol1ecten ;rrad;anc~(the Atlantic bay scallop), A. gibbus(the calicoscallop), and fl!rcol1ecten maaellan;cus (the seascallop). P. magellanicus is the most important interms of commE~rcial fisheries. It had a docksidevalue of about j' 28 million dollars in 1988. Thebay scallop is probably the most important forrecreational fisheries. It will be the focus of muchof this section.
O. VulgarisC. VirginicaC. GiganteaA. IrradiansA. Gibbus
ClassBivalvia
American OysterRock scallopBay scallopCalico scallop
C. VirginicaC. GiganteaA. IrradiansA. Gibbus
FamilyPectinidae
Rock scallopBay scallopCalico scallop
C. GiganteaA. IrradiansA. Gibbus
GenusArgopectin
Calico scallopBay scallop
A. GibbusA.lrradians
(Most Specific)A. irradians
SpeciesBay scallop
The AtlaIJ.tic Bay scallop is found inbays and es1uaries from Massachusettsto the Floridcl Peninsula, it then followsthe coastline along the Gulf of Mexicoto Southern Texas. They are usuallyfound on saIld-mud bottoms,associated with eel grass patches.
Three subspecies are currentlyrecognized: ..t\rgopectin irradiansirradians is found from Cape Codsouth to New Jersey, A.i. concentricusis found frol11 New Jersey and followsthe coastline south and along the Gulfof Mexico until the Mississippi Deltawhich apparE~ntly serves as a barrierbetween this and the third subspecies.The third subspecies, A.i. amplicostatusis found only in Texas.
All are folmd in relatively shallowwaters. They have been reported indepths down to 20 meters but generallythey are fourld in water less than 12meters. This shallow depth makes theman easy species for man to harvest andat the same 1:ime it makes them more
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SCIENCE
Strand.the natUJ~e of matter and energy.processe:) that shape the earth.processes of life.how living things interact with theirenvironment.the nature of science
Standards
.understaJ1ds the need for protection ofthe natural systems on Earth.describes patterns of structure andfunction in living things.understands the competitive,interdependent, cyclic nature of livingthings in the environment.
on the bay scallop; it's shallow habitat isalso more prone to temperaturefluctuations and damage from storms.
Bay Scallops have a relatively shortlife span. A bay scallop rarely livesbeyond 2 years, whereas some scallopspecies may live over 20 years. The bayscallop spawn at the end of their firstyear and those that live for another yearspawn again at the end of their second.These longer lived bay scallops areusually found in the northern latitudes.The time of the year at which theyspawn also differs latitudinally. A.irradians irradians, the northernmostsubspecies spawns in the warmestmonths of the year, sometimesbeginning as early as May. A. I.concentricus at the southern edge of itsrange spawns when the weather turnscooler, usually in fall.
Bay Scallops are simultaneoushermaphrodites. That means they canproduce both sperm and eggs at thesame time. However, they usually releasetheir gametes asynchronously so thatself-fertilization does not occur. When acritical ambient temperature or when thesurrounding seawater reaches a criticaltemperature (appox. 25 degrees C) theyall release their gametes into the waterat the same time. Fertilization of theeggs therefore occurs in the externalenvironment. Scallops are foundtogether in large populations and byreleasing their gametes at the same timethis increases the chances of the eggsand sperm running into each other in thewater!
SOCIAL S1:1JDIES
Strand.people, places, and environments( Geograph~7)
Standards.understaJtlds the world in spatial terms.understands the interactions of peopleand the physical environment
