Noun
The terminal joint or movable piece at the end of the abdomen of Crustacea and other articulates. See Thoracostraca.
Source: Webster's dictionaryThe uropods and telson collectively form the tail fan; the uropods are not divided by a diaeresis, as they are in many other decapods. Source: Internet
The mouth is between segments two and three. citation The opisthosoma consists of twelve or fewer segments that originally formed two groups, a mesosoma of seven segments and a metasoma of five, terminating with a telson or spike. Source: Internet
The pleon (abdomen) is unsegmented in the first protozoea, and ends in a bilobed telson, which may be used for cleaning other appendages, or for steering. Source: Internet
The telson is flanked by a pair of long, thin caudal rami. Source: Internet