Triangular kidneyshell
Encyclopedia
The triangular kidneyshell, scientific name Ptychobranchus greenii, is a species
of freshwater mussel, in the family Unionidae
, the river mussels. It is endemic to Alabama
in the United States, where it is known from several rivers and streams in the Mobile River Basin
. It is a federally listed endangered species
of the United States.
This aquatic bivalve
mollusc is somewhat oval in shape and may reach 10 centimeters in length. It is yellow to yellow-brown in color. The shell is quite variable in appearance.
When this mussel breeds it releases its larva
e, termed glochidia
, glued together in packets called conglutinates. The conglutinate has a sticky filament that adheres to the substrate to prevent it from being washed away. The conglutinate resembles a fly larva, or perhaps a fish egg, and it is appetizing to fish. Fish hosts such as the warrior darter (Etheostoma bellator), Tuskaloosa darter (Etheostoma douglasi), and blackbanded darter (Percina nigrofasciata) consume the conglutinates, degrading them and releasing the glochidia, which then lodge in the fish's gills as parasites. They develop into juvenile mussels and drop out of the fish to develop further elsewhere. Many other mussels in family Unionidae have a similar process.
This mussel was known from the Black Warrior River
and tributaries
, the Coosa River
and its tributaries, and the Cahaba River
. When it was placed on the Endangered Species List in 1993 it was limited to some tributaries of the Black Warrior River and the Conasauga River
in the Coosa River drainage. Any remaining specimens in the Cahaba River are now treated as members of another species, Ptychobranchus foremanianus. It is extirpated from the main Black Warrior River, but it is present in at least two tributaries, which are protected within Bankhead National Forest.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of freshwater mussel, in the family Unionidae
Unionidae
Unionidae is a family of freshwater mussels, the largest in the order Unionoida, the bivalve mollusks sometimes known as river mussels, naiads, or simply as unionids.The range of distribution for this family is world-wide...
, the river mussels. It is endemic to Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
in the United States, where it is known from several rivers and streams in the Mobile River Basin
Mobile River
The Mobile River is located in southern Alabama in the United States. Formed out of the confluence of the Tombigbee and Alabama rivers, the approximately river drains an area of of Alabama, with a watershed extending into Mississippi, Georgia, and Tennessee. Its drainage basin is the...
. It is a federally listed endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
of the United States.
This aquatic bivalve
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
mollusc is somewhat oval in shape and may reach 10 centimeters in length. It is yellow to yellow-brown in color. The shell is quite variable in appearance.
When this mussel breeds it releases its larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, termed glochidia
Glochidium
The glochidium is a special microscopic larval stage of larger freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels....
, glued together in packets called conglutinates. The conglutinate has a sticky filament that adheres to the substrate to prevent it from being washed away. The conglutinate resembles a fly larva, or perhaps a fish egg, and it is appetizing to fish. Fish hosts such as the warrior darter (Etheostoma bellator), Tuskaloosa darter (Etheostoma douglasi), and blackbanded darter (Percina nigrofasciata) consume the conglutinates, degrading them and releasing the glochidia, which then lodge in the fish's gills as parasites. They develop into juvenile mussels and drop out of the fish to develop further elsewhere. Many other mussels in family Unionidae have a similar process.
This mussel was known from the Black Warrior River
Black Warrior River
The Black Warrior River is a waterway in west central Alabama in the southeastern United States. The river rises in the extreme southern edges of the Appalachian Highlands and flows 178 miles to the Tombigbee River, of which the Black Warrior is the primary tributary...
and tributaries
Tributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
, the Coosa River
Coosa River
The Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long altogether.The Coosa River is one of Alabama's most developed rivers...
and its tributaries, and the Cahaba River
Cahaba River
The Cahaba River is the longest free-flowing river in Alabama and is among the most scenic and biologically diverse rivers in the United States. The Cahaba River is a major tributary of the Alabama River and part of the larger Mobile River Basin...
. When it was placed on the Endangered Species List in 1993 it was limited to some tributaries of the Black Warrior River and the Conasauga River
Conasauga River
The Conasauga River is a river that runs through southeast Tennessee and northwest Georgia. The Conasauga River is long and is home to 90 species of fish and 25 species of freshwater mussels...
in the Coosa River drainage. Any remaining specimens in the Cahaba River are now treated as members of another species, Ptychobranchus foremanianus. It is extirpated from the main Black Warrior River, but it is present in at least two tributaries, which are protected within Bankhead National Forest.
External links
- Bogan, A.E. 1996. Ptychobranchus greenii. 2011 IUCN Red List of Threatened Species. Downloaded on 16 September 2011.