2019_programme: MECHANORECEPTORS IN EARLY DEVELOPMENTAL STAGES OF THE PYCNOGONIDA

• Session: 03. Acoustic Monitoring of Ocean Environments and Processes: Biology, Ecology, Geophysics and Man-made activities
  Organiser(s): Ratilal Purnima, Miksis-Olds Jennifer
• Lecture: MECHANORECEPTORS IN EARLY DEVELOPMENTAL STAGES OF THE PYCNOGONIDA
  Paper ID: 742
  Author(s): Fornshell John
  Presenter: Fornshell John
  Presentation type: oral
  Abstract: Mechanoreceptors in Early Developmental Stages of the Pycnogonida\n\n John A. Fornshell\n\n National Museum of Natural History,\n Department of Invertebrate Zoology,\n Smithsonian Institution, Washington, DC\n \n\n Members of the phylum Arthropoda detect fluid flow or sound/particle vibrations using organs called sensilla. These sensilla detect sound/particle vibrations in the boundary layer. In the present study, archived specimens from the National Museum of Natural History were examined in an effort to extend our knowledge of the presence of sensilla on the early post hatching developmental stages, first and second instars, of pycnogonids. In the work presented here we look at three families, four genera and eight species of early post hatching developmental stages of sea spiders. They are Family Ammotheidae, Achelia cuneatis Child, 1999, Ammothea allopodes Fry and Hedgpeth, 1969, Ammothea striata (Möbius, 1902), Family Nymphonidae, Nymphon grossipes (Fabricius, 1780), N. australe Hodgson, 1902, N. charcoti Bouvier, 1911, N. Tenellum (Sars, 1888) and Pycnogonidae, Pentapycnon charcoti Bouvier, 1910. Electron micrograph images of these species were used to identify and describe the sensilla present.\n Most body organs such as mouthparts, the eye tubercle, appendages and spines are proportionally much smaller in the early post hatching developmental stages compared to their size in the adults, while the sensilla are comparable in size and shape to those found on the adults. In the first instar of Pentapycnon charcoti sensilla are present, but not in the adult (Fornshell and Harlow, 2018). The sensilla have an external morphology homologous to the sensilla found on adult pycnogonids. The sensilla shaft lengths are tens of microns and two to seven in number. It is only possible to establish the presence of sound detecting sensilla. Their functionality remains to be established in future experimental work. Theoretical detection ranges of 1 to 100 m and 10 to 1 kHz are possible. \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
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• Corresponding author: Dr Fornshell John
  Affiliation: National Museum of Natural History, SMithsonian Institution
  Country: United States
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