New record of viviparity for the dominant benthic invertebrate Exogone hebes (Polychaeta: Syllidae) from the Grand Banks of Newfoundland

• Main Authors: Patricia Pocklington, Michael S. Hutcheson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Newfoundland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.598.2119; http://www.int-res.com/articles/meps/11/m011p239.pdf

ABSTRACT: The dominant infaunal benthic invertebrate on the Grand Banks of Newfoundland, Exogone hebes, is viviparous. This is the first recorded case of such development for this genus. Scanning electron microscopy documents the presence of fully differentiated juveniles within modified segments. On separation from the female, each juvenile was 7 segments long, had a fully developed antenna, pharynx, 5 setigerous segments and a pygidium with anal cirri. The juveniles were extruded via the nephridial pores. Previously, external brooding of eggs and larvae has been described for this species. Incubating females were observed from March to November with a spawning maximum in spring (May). These new observations suggest a possible reason for the obvious ecological success of the species in one of the colder parts of its range.