COPEPODA 



By Waldo L. Schmitt, United States National Museum 



In view of the admitted importance of copepods 

 in the economy of the sea it is rather surprising 

 tliat so little attention has been given the free- 

 swimming forms of the Gulf of Mexico. This 

 may, in great measure, be due to the fact that 

 their systematic study entails much painstaking 

 effort. They are small, and their precise determi- 

 nation requires microscopic dissection and the 

 preparation of slide mounts. Also, the collecting 

 of the specimens needed for an adequate review 

 of the species and a knowledge of their distribution 

 and the conditions of their existence in any large 

 body of water is an expensive undertaking involv- 

 ing the employment of vessels, equipment, and 

 men over a considerable period of time. 



Not until the spectacular recurrence of the 

 "red tide" in 1946-1947 had more than casual and 

 localized samplings ever been attempted, but the 

 comprehensive sm-vey initiated at that time seems 

 not as yet to have progressed beyond the list of 

 species and a brief discussion published by King 

 (1950). In his table of plankton distribution there 

 are entered 67 copepods in 50 genera (excluding 

 the pelagic stages of 2 parasitic forms belonging to 

 2 different genera). Thirteen of these were not 

 accompanied by specific determination, so the 

 number of species could easily be greater if any 

 of these genera were represented by more than 

 one species. 



The earliest report enumerating Gulf species 

 consists of Herrick's (1884) work in which he 

 writes, "jottings . . . the result of a few days' 

 stay on Mississippi Sound . . . will give some 

 idea of the [copepod] fauna of the Gulf of Mexico." 

 Of the eight free-swimming species he collected, 

 two represented new species, one, indeed, a new 

 genus. Along with their descriptions he published 

 descriptive notes on five of the six other species. 



Tliree years later Herrick's (1887) paper ap- 

 peared in which the material on the species of the 

 earlier report was reproduced with emendations 

 and illustrations and two species added; two of 



the more or less tentatively identified forms of the 

 earlier report were redescribed as new, of which 

 one was referred to a different genus. The number 

 of free-swimming salt and brackish water species 

 recorded by Herrick from Mobile Bay and vicinity 

 thus totals about 10. A few of these are again 

 dealt with by Herrick and Turner (1895) but 

 without particular reference to their occurrence in 

 the salt or brackish waters of Alabama. 



No further study of the free-swimming copepods 

 seems to have been made until Foster (1904) 

 prepared his notes on the free-swimming copepods 

 of the waters in the vicinity of the Gulf Bio- 

 logical Station, Louisiana, in which 13 genera 

 were presumably represented by 18 species, 

 though at least 1 species in each of 6 genera was 

 not specifically determined. Foster's specimens 

 were collected 6 to 8 miles out in the Gulf of 

 Mexico, in Calcasieu Pass, and in St. Johns 

 Bayou which connects Lake Calcasieu with the 

 Pass. 



A representative of each of two genera not 

 appearing either in King's table or in Foster's 

 list were identified by Herrick also. With these 

 exceptions King seems to have found about every- 

 thing taken by those authors and, of course, 

 many more genera and species besides. Otherwise, 

 no extensive gatherings of free-swimming copepods 

 have been reported on, though some very re- 

 markable additions resulted from A. S. Pearse's 

 visits to the former Tortugas Laboratory of the 

 Carnegie Institution. In brackish ponds and 

 pools Pearse (1932a) discovered four species of 

 copepods in as many genera of which one genus 

 and three of the species proved to be new records 

 for the Gulf area. From among the numerous 

 inhabitants of certain Tortugas sponges he 

 (Pearse 1932b) sorted 23 different kinds of cope- 

 pods not identified except as to the 12 genera to 

 which the species belong. Nine of these likewise 

 constituted new records. Finally, in the giU 

 chambers of three species of crabs that he (Pearse 



439 



