The rare siphonophore Rhizophysa eysenhardtii Gegenbaur, 1859 (Hydrozoa, Siphonophora, Cystonectae) from False Bay, South Africa

By

Mapstone, Gillian M
Landschoff, Jannes

Type

Article

Date of Publication

2024-12-10

Original Publication

African invertebrates : a journal of biodiversity research

Volume

65

Series / Issue

Issue: 2

Pages

213--221

Subjects

Benguela ecosystem , cystonect , Diet , Great African Seaforest , in situ observation , photo and video identification

Contributed by

Pensoft Publishers

Language

English

Published by

Pietermaritzburg, South Africa Council of the Natal Museum 2001-

Identifiers

DOI: https://doi.org/10.3897/AfrInvertebr.65.136267

 

Abstract

From June to September 2022, five colonies of the rare hydrozoan siphonophore Rhizophysa eysenhardtii were observed for the first time near the surface in False Bay, South Africa. The two colonies in June/July were small with all tentacles contracted, while the September colonies were larger, the largest up to 0.8 m long (in video), with most of its tentacles extended for feeding. In this species, tentacles are typically pink and each arises from the proximal end of a gastrozooid, which engulfs and digests the prey. Fish larvae were noted in the gastrozooids and counted and a chaetognath was observed stuck to one of the tentacles. The pneumatophore was prominent in all specimens and gonodendra bearing sexual gonophores were visible between the gastrozooids of the larger specimens.