Chaetognatha
Key for the identification of genera and species

The key to Chaetognatha starts at Page 1719: Chaetognatha. This key applies to the genera and species found in the South Atlantic and also to the genera of the family Heterokrohniidae which may be found in this area in the future. It essentially refers to well-preserved, adult animals. Characters such as the shape of the seminal vesicles cannot be used for juveniles, whose identification should preferably be left until after that of adults. Moreover, it must be kept in mind that the adult morphology of some species may vary considerably with ecological conditions (like, for example, the winter and summer generations in Sagitta crassa forma tumida, see Tokioka, 1974), for which reason complementary diagnostic features for the species treated are provided separately [[l][textfile]complementary_diagnostics.txtComplementary diagnostics[/textfile][/l] ]. The following abbreviations may be used for characters in the key and descriptions (see also figures Sagitta in ventral view and head, dorsal view):

AF: anterior fins
AT: anterior teeth
BL: total body length (without tail fin)
PF: posterior fins
PT: posterior teeth
SV: seminal vesicles
TF: tail fin (or caudal fin)
TM: transverse muscles
TS: tail segment
VG: ventral ganglion