Zoological Studies

Vol. 51 No. 7, 2012

A Fifth Morphological Polyp in Pennatulacean Octocorals, with a Review of Polyp Polymorphism in the Genera Pennatula and Pteroeides (Anthozoa: Pennatulidae)

Gary C. Williams1,*, Bert W. Hoeksema2, and Leen P. van Ofwegen2

1Department of Invertebrate Zoology and Geology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA
2Netherlands Centre for Biodiversity Naturalis, Darwinweg 2, Leiden 2333 CR, the Netherlands

Gary C. Williams, Bert W. Hoeksema, and Leen P. van Ofwegen (2012) Four types of polyps that differ in morphology and function were previously described in pennatulacean octocorals: oozooids, autozooids, siphonozooids, and mesozooids.  Here we describe a 5th type of polyp, the acrozooid, found in members of 2 species of the genus Pteroeides from tropical western Pacific coral reef regions.  The polyps appear in clusters of up to 14 in number on the ventral side and distal terminus of the rachis, and are characteristically urn-shaped, with 8 triangularly shaped tentacles.  The polyp walls contain smooth, elongated rod-like sclerites, which are similar to those found in the coenenchyme of parent colonies.  We postulate that these polyps represent maturing asexual budding structures.

Key words: Sea pens, Acrozooids, Asexual budding, Zooids, Western tropical Pacific.

*Correspondence: E-mail:gwilliams@calacademy.org