Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 COPEPODA. 431 the respiratory function. Circulatory organs are either replaced by the regi^lar oscillations of the intestinal canal [Ci/clopSy Achtlieres), or there is present in the anterior part of the thorax above the intes- tine {Calanidca) a short saccular heart, which may even be continued into a cephalic artery {Calanella) (fig. 53). Generative organs.—The Cojicpoda are of separate sexes. Both kinds of genital organs lie in the c
Elementary text-book of zoology, general Elementary text-book of zoology, general part and special part: protozoa to insecta elementarytextbo00clau Year: 1892 COPEPODA. 431 the respiratory function. Circulatory organs are either replaced by the regi^lar oscillations of the intestinal canal [Ci/clopSy Achtlieres), or there is present in the anterior part of the thorax above the intes- tine {Calanidca) a short saccular heart, which may even be continued into a cephalic artery {Calanella) (fig. 53). Generative organs.—The Cojicpoda are of separate sexes. Both kinds of genital organs lie in the cephalothorax and in the thoracic segments, and open right and left on the basal segment of the abdomen. Sexual differences in the form and structure of the different parts of the body are almost uniformly found. These lead Fig. 342.—Metamorphosis of Cyclops, a, Nauplius larva of Ci/clops serrulaius after hatching. b. Older stage strongly magnified, c. Very young Cyclops form. SD, antennal glands ; 01, upper lip; Mf, mandibular foot; Md, mandible ; Mx, maxilla, Mxf, masilliped ; J-*, JP', first and second swimming feet; He, iirinary concretions; D, intestine; Ad, rectum; A, anus ; G, rudimentary genital organs. in certain parasitic Copepoda {Chondracanthidce, Lernceopodidce) to an extremely striking dimorphism. The males are smaller and move with greater facility; the anterior antennte and the last pair of feet become accessory copulatory organs, the former serving to hold the female, the latter to affix the spermatophores. The sper- matophores are formed in the vas deferens by a mucous secretion which surrounds the seminal mass and hardens to a tough mem- brane. The females are larger than the males and often move
Size: 1584px × 1262px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
