Occurrence of a shadow response among brachyuran larvae


Journal Article

A closed-circuit television system was used to study phototaxis and behavioral responses upon sudden decreases in light intensity in light-adapted Stage I zoeae from 7 species of Brachyura (Panopeus herbstii, Menippe mercenaria, Uca pugilator, Callinectes sapidus, Sesarma cinereum, Pinnotheres maculatum, and Libinia emarginata). All species except one show positive phototaxis to high intensities of 500 nm light and negative phototaxis to low intensities. Upon a sudden light intensity decrease, larvae show a shadow response, which depends upon the initial and final intensities. If the initial intensity is sufficient to induce positive phototaxis, and the light is extinguished, the larvae of 6 species stop swimming and passively sink (sinking response). Reducing the intensity to an absolute level that causes negative phototaxis, induces a sinking response followed by negative phototaxis. For intensity reductions that occur in the intensity range above that for negative phototaxis, a sinking responseis observed. The intensity decrease that initiates the sinking response is independent of initial stimulus intensity and duration, is consistent between species, and is equivalent to a decrease by 0.5 OD (optical density) units. The sinking response is greatest at intensity decreases of at least 1.0 to 1.1 OD units. It is concluded that the shadow response is common in brachyuran larvae inhabiting coastal-estuarine areas. © 1977 Springer-Verlag.

Full Text

Duke Authors

Cited Authors

  • Forward, RB

Published Date

  • February 1, 1977

Published In

Volume / Issue

  • 39 / 4

Start / End Page

  • 331 - 341

Electronic International Standard Serial Number (EISSN)

  • 1432-1793

International Standard Serial Number (ISSN)

  • 0025-3162

Digital Object Identifier (DOI)

  • 10.1007/BF00391936

Citation Source

  • Scopus