Rare 'jellyfish' spotted in False Bay for the first time

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This finding in False Bay, published in African Invertebrates, extends the known range of this elusive species by 450 kilometres.

It also highlights the rich and fragile biodiversity of South Africa’s marine ecosystems, particularly the Great African Seaforest.

The siphonophore is known as Rhizophysa eysenhardtii. Siphonophores are fascinating marine organisms belonging to the phylum Cnidaria, which includes jellyfish, corals, and sea anemones.

Unlike most creatures, they are colonies made up of specialized individuals called “zooids,” working together as one entity. The Rhizophysa eysenhardtii specimens were observed by freedivers between June and September 2022.

“When I saw this siphonophore for the first time, I got so excited and couldn’t believe my eyes,” said Dr. Jannes Landschoff, a marine biologist with the Sea Change Project and a research fellow at Stellenbosch University’s Botany and Zoology Department.

“I immediately knew it was a special discovery, and I wanted to learn more about this exquisite life form.”

*Rhizophysa eysenhardtii* have characteristic pink tentacles and translucent bodies. Image: Stellenbosch University

A special kind of jellyfish

The study’s first author, Dr. Gill Mapstone from the Natural History Museum in London, has spent her career studying siphonophores.

“These animals are rarely documented, despite their ecological importance,” she said.

Underwater photos and videos of the ‘jellyfish’ revealed the species’ striking pink tentacles and translucent bodies. Observations also showed that the siphonophore feeds on fish larvae and, in one instance, a chaetognath. This is a small predatory marine worm.

“Seeing the photos of these spectacular animals made me realise once more why I started working on this group in the first place,” she added. “They are just so incredible,”

A boost for marine biodiversity

This discovery sheds light on the region’s biodiversity and raises questions about shifting marine ecosystems. False Bay is part of the Benguela Ecosystem, a vital marine area influenced by ocean currents and environmental changes.

The presence of Rhizophysa eysenhardtii in this region could indicate changes in the species’ distribution patterns.

Protecting habitats like the Great African Seaforest is vital for preserving these species and the ecological services they provide, said the department.

“Our findings underscore the need to safeguard marine biodiversity and improve documentation of rarely observed species,” Landschoff concluded.