Changes in the Visual Fields Associated With Web Reduction in the Spider Family Uloboridae

Data di pubblicazione: 1987

Da: ConchBooks, Harxheim, GermaniaConchBooks

Venditore con 3 stelle

Venditore AbeBooks dal 1 marzo 2007

Condizione: Usato

EUR 6,00

EUR 24,00 spedizione 
Spedito da Germania a U.S.A.

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Descrizione dell’articolo da parte del venditore

When visual fields of the primitive orb-weaver, Waitkera waitkerensis, are reconstructed using measurements taken from intact lenses and cross and longitudinal sections of the prosoma, they show that this species has complete visual surveillance, but that none of the visual fields of its eight eyes overlap. The more advanced orb-weaver, Uloborus glomosus, also has eight eyes, but each eye has a greater visual angle, giving this species a complex pattern of overlapping visual fields. Uloborids that spin reduced webs are characterized by reduction or loss of the four anterior eyes and other carapace modifications necessary for them to effectively monitor and manipulate their reduced webs. The eyes of these uloborids have greater visual angles than those of orb-weavers, resulting primarily from perimetric expansion of their retinal hemispheres. Additionally, the axes of their visual fields are more ventrally directed due to greater dorsal than ventral retinal expansion and to ventral redirection of the entire eye. Consequently, even though the anterior lateral eyes of the triangle-weaver Hyptiotes cavatus lack retinae, the species six functional eyes permit complete visual surveillance and exhibit visual overlap. The single-line-weaver, Miagrammopes animotus, has lost its four anterior eyes, and with them much of the anterior vision and all of the visual overlap found in the other species. However, changes similar to those of H. cavatus permit this species to retain most if its dorsal and ventral visual surveillance. Thus, ocular changes act in consort to maintain relatively complete visual surveillance in the face of eye loss and other major carapace modifications necessary for the operation of reduced webs. 14 pp., 4 figs, 3 tabs, gr. 8.…

Codice articolo W36101

Dati bibliografici

Titolo
Changes in the Visual Fields Associated With Web Reduction in the Spider Family Uloboridae
Autore
Opell, B. D. & Ware, A. D.
Anno di pubblicazione
1987

ConchBooks

Harxheim, Germania

Venditore con 3 stelle

Venditore AbeBooks dal 1 marzo 2007

Tariffe di spedizione da Germania a U.S.A.

ArticoloDa 25 a 45 giorni lavorativiDa 8 a 14 giorni lavorativi
Primo articoloEUR 24,00EUR 34,00
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Descrizione dello Store

Founded in 1985 we are specialized in worldwide literature on Mollusca and marine invertebrates. Our publishing house has meanwhile published approximately 60 titles on that field of interest. We have stocks of most available international books on Malacology and a huge amount of antiquarian literature, even of the latter most titles are only available once.

Specializzazione

Weichtiere / Shells, Schnecken / Snails & Slugs, Muscheln / Bivalves, Tintenfische / Squids / Octopusses / Ammonites, Malacology, Conchology, Marine Biology