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Ultrastructure of the “pigment knob” of Pleuromamma spp. (Copepoda: Calanoida)
Author(s) -
BladesEckelbarger Pamela I.,
Youngbluth Marsh J.
Publication year - 1988
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051970306
Subject(s) - ultrastructure , biology , arthropod cuticle , calanoida , pigment , copepod , anatomy , cuticle (hair) , hemolymph , zoology , crustacean , botany , insect , chemistry , organic chemistry
The calanoid copepod genus Pleuromamma is easily distinguished from all other copepods by the presence of a rounded, dark‐red cuticular structure ( = pigment knob) that protrudes from the left or right side of the second thoracic segment in both sexes. The present study of the pigment knob reveals a complex ultrastructure consisting of various cell types within three distinct areas that are bathed by hemolymph from the lateral sinus. The knob is covered by a greatly expanded cuticle through which a pore passes. The pore appears to connect with a centrally positioned pigment cell containing a large mass of darkly staining granules. This suggests that the knob may have a secretory function. Observations of live animals and dissected pigment knobs, however, indicates that the knob does not secrete a luminescent material nor does it luminesce internally.