Valve sculpturing and aesthete distributions in four species of Australian chitons (Mollusca: Polyplacophora)

Currie, David J.

doi:10.1080/00852988.1989.10674008

Cited by 5 publications

(2 citation statements)

References 11 publications

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“…Sumner-Rooney 2018). It appears that the individual eyes of both subfamilies are similar, but there are organizational-level differences among acanthopleurine species in the aesthete networks around the eyes (Currie, 1989). There may be also be significant differences in their visual networks that we are yet to discover.…”

Section: Discussionmentioning

confidence: 89%

“…Further comparisons between T. lebruni and existing work, largely concerning members of the subfamily Acanthopleurinae (Speiser et al 2011;Currie, 1989), should account for the distinct differences in their visual environments. Acanthopleura and related species are largely of tropical and subtropical distribution, where high light intensity and relatively clear waters likely provide an abundance of visual information and facilitate, for example, the detection of overhead shadows.…”

Section: Discussionmentioning

confidence: 99%

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Continuous and Regular Expansion of a Distributed Visual System in the Eyed ChitonTonicia lebruni

Sigwart

Sumner‐Rooney

2021

The Biological Bulletin

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Chitons have a distinctive armature of eight articulating dorsal shells. In all living species, the shell valves are covered by a dense array of sensory pores called aesthetes, but in some taxa, a subset of these are elaborated into lensed eyes, which are capable of spatial vision. We collected a complete ontogenetic series of the eyed chiton Tonicia lebruni to examine the growth of this visual network, and found that it expands continuously as eyes are added at the margin during shell growth. Our dataset ranged from a 2.58 mm juvenile with only 16 eyes to adults of 25-31 mm with up to 557 eyes each. This allowed us to investigate the organization and potential constraints therein of these sensory structures and their development. Chiton eyes are constrained to a narrowly defined region of the shell, and data from T. lebruni indicate they are arranged roughly bilaterally symmetrically. We found deviations from symmetry of up to 10%, similar to irregularity reported in some other animals with multiplied eyes.Distances separating successive eyes indicate that, while shell growth slows during the life of an individual chiton, eyes are generated at regular time intervals. Although we could not identify a specific eye-producing tissue or organ, we propose that the generation of new eyes is controlled by a clock-like mechanism with a stable periodicity.The apparent regularity and organization of the chiton visual system is far greater than previously appreciated. This does not imply the integration of shell eyes to form composite images, but symmetry and regular organization could be equally beneficial to a highly duplicated system by ensuring even and comprehensive sampling of the total field of view.

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Continuous and Regular Expansion of a Distributed Visual System in the Eyed ChitonTonicia lebruni

Sigwart

Sumner‐Rooney

2021

The Biological Bulletin

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Aesthete Pattern Diversity in Chiton Clades (Mollusca: Polyplacophora): Balancing Sensory Structures and Strength in Valve Architecture

Ampuero,

Vončina,

Parkinson

et al. 2024

Journal of Morphology

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Chitons possess the most elaborate system of shell pores found in any hard‐shelled invertebrate. Although chitons possess some anteriorly located sense organs, they lack true cephalization, as their major sensory systems are not concentrated in a distinct head region. Instead, the aesthete system within their shells forms a dense sensory network that overcomes the barrier of their hard dorsal armour. The basic arrangement of neural structures embedded within a solid, opaque matrix, has confounded understanding of the overall network. In this study, we use synchrotron X‐ray μCT to visualise the aesthete canal networks inside chiton valves. We selected representatives from all three major chiton clades: Lepidopleurida, the basal branching clade, and Callochitonida and Chitonida, which both have more complex shell morphology, to compare internal structure. Lepidopleurida aesthete canals are oriented vertically and pass directly through the shell to connect with the body. By contrast, aesthetes canals in Callochitonida and Chitonida have complex internal structures with extended horizontal passages, coalescing at the shell diagonal that corresponds to the valve insertion slits. This represents a stepwise evolution of chiton shell form, where thicker and more complex valves require a diverting and rewiring of the entire sensory network. Aspects of the aesthete system, such as the microscopic arrangement of surface pores, have long been used in chiton taxonomy for species diagnoses; insertion slits should also be understood as a secondary feature of the aesthete system. Chiton shell structures that are used for morphological systematics are driven by sensory adaptations.

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Optimized Sensory Units Integrated in the Chiton Shell

Liu

Huang

et al. 2022

Mar Biotechnol

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Valve sculpturing and aesthete distributions in four species of Australian chitons (Mollusca: Polyplacophora)

Cited by 5 publications

References 11 publications

Continuous and Regular Expansion of a Distributed Visual System in the Eyed ChitonTonicia lebruni

Continuous and Regular Expansion of a Distributed Visual System in the Eyed ChitonTonicia lebruni

Aesthete Pattern Diversity in Chiton Clades (Mollusca: Polyplacophora): Balancing Sensory Structures and Strength in Valve Architecture

Optimized Sensory Units Integrated in the Chiton Shell

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