EVOLUTIONARY STRATEGIES OF THE ANTENNAE IN TERRESTRIAL ISOPODS

The conquest of terrestrial habitats by the Oniscidea necessitated the development of a moisturemonitoring system. This function is ascribed to the flagellar aesthetascs present on both first and second antennae, in addition to their olfactory function. The extreme diminution of the first antennae p...

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Bibliographic Details
Published in:Journal of crustacean biology 1998-02, Vol.18 (1), p.10-24
Main Author: Schmalfuss, Helmut
Format: Article
Language:English
Subjects:
Animals
Antennas
Biotopes
Crustaceans
Flagella
Insect antennae
Legs
Predators
Taxa
Zoology
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Summary:The conquest of terrestrial habitats by the Oniscidea necessitated the development of a moisturemonitoring system. This function is ascribed to the flagellar aesthetascs present on both first and second antennae, in addition to their olfactory function. The extreme diminution of the first antennae prevents them from being inactivated by predator actions, thus guaranteeing the vital monitoring of moisture-gradients in case the second antennae are destroyed by predators. The change from littoral to endogean and epigean biotopes has been accompanied by a reduction of flagellar articles in the second antennae. Thus, the terminal gustatory organ can be operated more precisely, meeting the need for exact food localization. The second antennae have additional functions as part of the water conducting system and as a lever to move the animal from a dorsal to a ventral position when overturned. Conglobation provides effective protection for the antennae, and in the superfamily Oniscoidea, the only group surviving under periodic desiccation, the antennal flagellum is cleaned by an obviously indispensable grooming device on the first walking leg.
ISSN:0278-0372
1937-240X
DOI:10.1163/193724098X00025