Abstract Eye development, optical properties and photomechanical responses were examined in embryos and hatchlings of the southern calamary, Sepioteuthis australis. This species occurs in shallow coastal waters in Australia and New Zealand, and the egg masses were collected in October and December 2004 from Great Oyster Bay, Tasmania. At the earliest developmental stage the eye of the squid was comprised of a hemispherical cup of undiVerentiated neural retina, while presumptive iris cell layers and lentigenic precursor cells enclosed a posterior eye chamber. DiVerentiation of the proximal and distal processes was observed in correspondence with the cornea development and lens crystallization, and occurred before diVerentiation of the neural retina, which was complete prior to hatching. Longer photoreceptor distal processes were Wrst observed just prior to hatching in the dorsal-posterior retina. After hatching, this diVerence was much more evident and higher photoreceptor density was found in the central retina. This indicates that the eye of S. australis at this age uses diVerent retina areas for diVerent visual tasks. Optical sensitivity and resolution suggest that juvenile S. australis are diurnal. This study also found functional photomechanical responses of visual screening pigment migration and pupil constriction in S. australis embryos, although complete functionality of the pupil at this stage was uncertain. However, the pupils of squid aged 2 days closed almost completely under bright conditions, showing that photomechanical responses were highly developed in the juvenile squid. These Wndings indicate that squid embryos are able to perceive visual stimulation, suggesting an early reliance on vision for survival after hatching.

Item Type:	Refereed Article
Research Division:	Biological Sciences
Research Group:	Zoology
Research Field:	Animal structure and function
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the biological sciences
UTAS Author:	Bozzano, A (Dr Anna Bozzano)
UTAS Author:	Moltschaniwskyj, NA (Associate Professor Natalie Moltschaniwskyj)
UTAS Author:	Villanueva, R (Dr Roger Villanueva)
ID Code:	58179
Year Published:	2009
Web of Science® Times Cited:	9
Deposited By:	NC Marine Conservation and Resource Sustainability
Deposited On:	2009-09-10
Last Modified:	2012-03-05
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