Acta Arachnologica
Online ISSN : 1880-7852
Print ISSN : 0001-5202
ISSN-L : 0001-5202
Search
Advanced search
OR
Browse
Search
Volume 34, Issue 1
Displaying 1-3 of 3 articles from this issue
Show all abstracts
    • |<
    • <
    • 1
    • >
    • >|
  • The effects of salinity on embryonic development of the horseshoe crabs
    Hiroaki SUGITA, Kiminobu MURAKAMI, Koichi SEKIGUCHI
    1985Volume 34Issue 1 Pages 1-9
    Published: 1985
    Released on J-STAGE: March 29, 2007
    DOIhttps://doi.org/10.2476/asjaa.34.1
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Horseshoe crabs are found in coastal and estuarine areas and, when the tide is on the flow, the mature adults migrate shorewards to spawn on sandy beaches. The salinity measured was 18-33‰ in Tatara coast where Japanese horseshoe crabs were laying eggs. Therefore, eggs and embryos as well as adults of horseshoe crabs were expected to tolerate a moderate reduction in salinity. In this experiment, the eggs of four horseshoe crab species, Tachypleus tridentatus, T. gigas, Carcinoscorpius rotundicauda, and Limulus polyphemus, were artificially inseminated and reared until hatching in different salinities ranging from 5‰ to 35‰. The embryos of all the four species were considered adaptable to the salinity ranges of their natural localities. The viability of C. rotundicauda embryos in low salinity was the lowest of all horseshoe crabs, though only C. rotundicauda goes up a river to spawn on the muddy banks of the river below the highest tidal level.
    View full abstract
    Download PDF (698K)
  • Comparison in the web structure between Nephila clavata L. KOCH and Nephila maculata (FABRICIUS) (Araneae: Araneidae), and the origin of genus Nephila
    Akira SHINKAI
    1985Volume 34Issue 1 Pages 11-22
    Published: 1985
    Released on J-STAGE: March 29, 2007
    DOIhttps://doi.org/10.2476/asjaa.34.11
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    The web structure of the two Nephila species, N. clavata and N. maculata, were compared. The juvenile webs of the two species had the same structure except for the form of the barrier webs. Their main webs resembled the normal orb-web.
    However, there were some differences in the adult female web of the two species. The web of N. clavata was more assymmetric than that of N. maculata. The web of N. clavata had the branched radii, the divided radii and the barrier constructions, while the web of N. maculata never had the divided radii and the barrier webs, but they had the branched radii only. These differences suggested that the web of N. clavata was more specialized than that of N. maculata, and that the Nephila species derived from the ordinary orb weaving ancestor.
    View full abstract
    Download PDF (2188K)
  • BROOD-CARE BEHAVIOR IN THERIDION JAPONICUM OBSERVED AT A LABORATORY
    Chizuko ITO
    1985Volume 34Issue 1 Pages 23-30
    Published: 1985
    Released on J-STAGE: March 29, 2007
    DOIhttps://doi.org/10.2476/asjaa.34.23
    JOURNAL FREE ACCESS
    Show abstractHide abstract
    Observations on the brood-care behavior in Theridion japonicum (Theridiidae) were carried out under a laboratory condition by using a video tape recorder.
    When a mother spider discovered a prey, she captured and chewed up the prey. Spiderlings began to crowd around the prey and clustered to suck it up about 17 min. later. After about 105 min., they dispersed gradually.
    The mother spider fed spiderlings in this way for about 3 weeks until the spiderlings began to take prey by themselves. When the spiderlings were about 7 weeks old, the mother died and her body was sucked out by the spiderlings. Then, spiderlings dispersed and started solitary life.
    Thus, Theridion japonicum will be ranked as “periodic-social” according to KULLMANN'S classification.
    View full abstract
    Download PDF (572K)
    • |<
    • <
    • 1
    • >
    • >|
feedback
 Top