The puzzling occurrence of the upside-down jellyfish Cassiopea (Cnidaria: Scyphozoa) along the Brazilian coast: a result of several invasion events?

Sergio N Stampar,Edgar Gamero-Mora,Juliano M Fritscher,Cláudio L S Sampaio,André C Morandini,Bruno S P Oliveira,Maximiliano M Maronna

doi:10.3897/zoologia.37.e50834

Abstract

The massive occurrence of jellyfish in several areas of the world is reported annually, but most of the data come from the northern hemisphere and often refer to a restricted group of species that are not in the genus Cassiopea. This study records a massive, clonal and non-native population of Cassiopea and discusses the possible scenarios that resulted in the invasion of the Brazilian coast by these organisms. The results indicate that this jellyfish might have invaded the Brazilian coast multiple times.

Highlights

Cassiopea medusae cover large areas in shallow environments. They can be recognized because they lay on the substrate with mouth arms facing upward, to which they owe the popular name “upside-down jellyfish”. Species of this genus are often found in mangrove areas, mainly because their polyps use the leaves of these plants as a substrate (Fleck and Fitt 1999)
The present study aims to refine the discussion about invasion events, mainly from a large population found in the tropical coast of Brazil (Maceió, state of Alagoas, NE Brazil)
Morphological study The 26 specimens collected resemble those previously identified as C. andromeda from Cabo Frio, SE Brazil (Morandini et al 2017)

Summary

Introduction

Cassiopea Péron & Lesueur, 1810 is a unique genus of large jellyfishes that occur in several shallow water environments around the world (Holland et al 2004). Cassiopea medusae cover large areas in shallow environments They can be recognized because they lay on the substrate with mouth arms facing upward, to which they owe the popular name “upside-down jellyfish”. Species of this genus are often found in mangrove areas, mainly because their polyps use the leaves of these plants as a substrate (Fleck and Fitt 1999). Polyp populations may multiply when the temperature increases, producing a large amount of free-swimming buds (Hofmann et al 1978) This reproductive pattern allows new polyps form rapidly from buds, and colonize other areas quickly (Curtis and Cowden 1971, Fitt and Costley 1998, Hofmann et al 2003)

Methods

Results

Conclusion