Marine Flora and Fauna of the Northeastern 



United States. Protozoa: Sarcodina: 



Benthic Foraminifera 



RUTH TODD and DORIS LOW' 



ABSTRACT 



An illuslraled key lo nearshore and shelf species includes 133 taxa. Seventy-nine genera are represented. In 

 an annotated list, the distribution and ecology of each species are recorded within the area of Cape Hatteras lo 

 Nova Scotia and out to a depth of 50 m on the continental shelf. The key is intended lo aid the nonspecialist in 

 identification of the species to be expected in the marshes, estuaries, littoral zone, bays, and inner parts of the 

 continental shelf. 



INTRODUCTION 



Foraminifera, an order within the class Sarcodina, are single- 

 celled animals characterized by having a rigid or flexible test, or 

 shell, and pseudopodia consisting of threads of protoplasm. 

 They primarily occupy marine waters, although a few species are 

 able to tolerate brackish conditions and extend into the inter- 

 tidal and estuarine zones. 



The floors of the outer continental shelf, the continental 

 slope, and the ocean basins (exclusive of the deepest parts of the 

 oceans where calcareous materials are dissolved because of the 

 undersaturation of calcium carbonate) are covered by vast 

 deposits of the empty shells of planktonic Foraminifera. 

 Planktonic Foraminifera, floating during life, shed their empty 

 shells onto the sea floor when the animals reproduce or die. This 

 deposit is known as Globigerma ooze in reference to one of the 

 principal genera involved. Planktonic Foraminifera are very rare 

 over the inner parts of the continental shelf, and none are 

 included in the present key. 



This key refers only to the bottom-dwelling or benthonic 

 species. Most of the species in the key are geographically wide 

 ranging. Some, such as Cibicides lobatulus and Miliammina 

 fusca, are recorded worldwide, within the limits of their respec- 

 tive environments. A few others, such as Hopkinsina atlantica 

 and Pseudopolymorphina phaleropei, seem to be restricted to a 

 small part of the area studied. A few of the commoner ones, 

 such as Elphidium banletti and Cribrostomoides jeffreysii, are 

 characteristic of Arctic and Subarctic regions. These seem not to 

 extend much farther south than Cape Cod, Mass. For a few 

 others, such as Elphidium galvestonense and Poroeponides 

 lateralis. Cape Cod appears to be the northern limit. Very few of 

 the species in this area, other than those having worldwide 

 distributions, are found in waters south of Cape Hatteras, N.C. 



Several reports describe and illustrate assemblages from 

 specific facies or areas of coastal regions along the northeastern 

 United States. Among the most useful of these are Bailey (1851); 

 Buzas (1965, 1968); Cushman (1944); Ellison and Nichols 

 (1970); Murray (1969); Parker (1948, 1952a, b); Parker and 

 Athearn (1959); Phleger and Walton (1950); Poag et al. (1980); 

 Ronai (1955); Schafer and Sen Gupta (1%90; Schnitker (1971); 



Scott and Medioli (1980); Shupack (1934); Tapley (1969); and 

 Todd and Low (1961). In addition, the following references pro- 

 vide useful records of distribution and details of morphology 

 pertaining to certain of the species of the northeastern United 

 States: Brady (1881c); Cushman (1918b, 1920, 1922a, 1923, 

 1929, 1930, 1931); Cushman and Ozawa (1930); Rhumbler 

 (1904); and Schultze (1854). 



MORPHOLOGY 



The morphology of Foraminifera is diverse. In shape they 

 range from a simple spherical or saclike chamber, with or 

 without a single opening, to many-chambered forms in which 

 the chambers succeed one another in a variety of ways, such as 

 in a straight or coiled sequence. The coiling may be complicated 

 by differences in the plane of coiling and by consisting of a 

 single or a double row of chambers. In addition, these shapes 

 and structures can be found combined with any of several kinds 

 of wall structure. Wails may be built of 1) various kinds of 

 foreign material gathered by the animal, or 2) calcium carbonate 

 extracted from seawater and then secreted by the animal, either 

 as solid layers or layers perforated by fine or coarse pores. 



CLASSIFICATION 



The shells of Foraminifera have been studied for some 150 yr, 

 initially as a hobby. Interest in them was greatly stimulated 

 shortly before 1920 when they began to be used in the search for 

 petroleum. Because of their small size and abundance in well 

 cores, they served as convenient means of working out geologic 

 structures. Foraminifera continue to be important in geologic 

 investigations, particularly in biostratigraphy, paleoecology, 

 and paleobiology. Very few species of Foraminifera have been 

 cultured for study as living animals, and these studies reveal how 

 little has been learned thus far about life cycles and the natural 

 classification of this highly plastic group of animals. 



Many classification systems have been applied to the order. 

 Loeblich and Tappan (1964), in addition to proposing the 

 classification currently in favor, summarized the earlier ones. 



'U.S. Geological Survey, Woods Hole, MA 02543. 



^Schafer, C. T., and B. K. Sen Gupta. 1969. Foraminiferal ecology in 



polluted estuaries of New Brunswick and Maine. Unpubl. manuscr., 24 

 p. Atl. Oceanogr. Lab., Bedford Inst., Dartmouth, N.S., Can., Rep. A.O.L. 

 69-1. 



