Meny

Javascript is not activated in your browser. This website needs javascript activated to work properly.
Du är här

Twilight orientation to polarised light in the crepuscular dung beetle Scarabaeus zambesianus

Författare:
Publiceringsår: 2003
Språk: Engelska
Sidor: 1535-1543
Publikation/Tidskrift/Serie: Journal of Experimental Biology
Volym: 206
Nummer: 9
Dokumenttyp: Artikel
Förlag: Company of Biologists Ltd

Sammanfattning

The polarisation pattern of skylight offers many arthropods a reference for visual compass orientation. The dung beetle Scarabaeus zambesianus starts foraging at around sunset. After locating a source of fresh droppings, it forms a ball of dung and rolls it off at high speed to escape competition at and around the dung pile. Using behavioural experiments in the field and in the laboratory, we show that the beetle is able to roll along a straight path by using the polarised light pattern of evening skylight. The receptors used to detect this skylight cue can be found in the ommatidia of the dorsal rim area of the eye, whose structures differ from the regular ommatidia in the rest of the eye. The dorsal rim ommatidia are characterised by rhabdoms with microvilli oriented at only two orthogonal orientations. Together with the finding that the receptors do not twist along the length of the rhabdom, this indicates that the photoreceptors of the dorsal rim area are polarisation sensitive. Large rhabdoms, a reflecting tracheal sheath and a lack of screening pigments make this area of the eye well adapted for polarised light detection at low light levels. The fan-shaped arrangement of receptors over the dorsal rim area was previously believed to be an adaptation to polarised light analysis, but here we argue that it is simply a consequence of the way that the eye is built.

Disputation

Nyckelord

  • Biology and Life Sciences
  • rhabdom
  • Scarabaeus zambesianus
  • dung beetle
  • orientation
  • receptor
  • ommatidia
  • polarisation pattern
  • skylight

Övriga

Published
Yes
  • Lund Vision Group
  • ISSN: 0022-0949

Box 117, 221 00 LUND
Telefon 046-222 00 00 (växel)
Telefax 046-222 47 20
lu [at] lu [dot] se

Fakturaadress: Box 188, 221 00 LUND
Organisationsnummer: 202100-3211
Om webbplatsen