Discovery reports (1956) Discovery reports discoveryreports27inst Year: 1956 DEVELOPMENTAL PHASES 365 The remaining thoracic appendages are the same as in the preceding stage except that the second cormopod has appeared and bears small gill lobes. The abdomen bears one setose and four non-setose pairs of pleopods. The condition of the telson remains unchanged. Remaining stages. The diagnostic characters of the remaining stages are given in Table 8. 0-5 mm Fig. 16. Euphausia lucens. a, second furcilia, lateral view; b, cephalothorax, dorsal view. As the animal approaches the adult form the
Discovery reports (1956) Discovery reports discoveryreports27inst Year: 1956 DEVELOPMENTAL PHASES 365 The remaining thoracic appendages are the same as in the preceding stage except that the second cormopod has appeared and bears small gill lobes. The abdomen bears one setose and four non-setose pairs of pleopods. The condition of the telson remains unchanged. Remaining stages. The diagnostic characters of the remaining stages are given in Table 8. 0-5 mm Fig. 16. Euphausia lucens. a, second furcilia, lateral view; b, cephalothorax, dorsal view. As the animal approaches the adult form the frontal plate becomes smaller and loses its serrations. In the adult phase this plate is a low triangle somewhat broader than long. It may or may not carry a rudimentary rostrum. The lateral denticle on the carapace moves gradually forward from its posterior position until it reaches about the middle of the inferior margin. The upper distal margin of the basal segment of the first antennal peduncle becomes progressively more produced until it is an acute, triangular lobe. A keel appears on the upper surface of the third segment. In the fifth and sixth stages the second antenna loses its natatory function and the endopod becomes segmented. Euphausia tenera Hansen It was not possible to identify any pre-furcilia stages of this species. Five furcilia stages of E. tenera were found in the plankton and are presented in Table 9. It seems highly probable that a sixth stage, with only a single terminal spine on the telson, also occurs, although it was not encountered.
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