Comb jellies fuse together when injured, study finds

Scientists Discover Comb Jellies Can Fuse Together When Injured

It might not be what the Spice Girls envisaged when they sang 2 Become 1, but scientists have found comb jellies do actually fuse together if they are injured.

Researchers studying a species of the gelatinous marine invertebrates known as “sea walnuts” said they made the discovery after spotting an unusually shaped individual in the laboratory tank.

“I was very excited,” said Dr Oscar Arenas, co-author of the work, from the University of California, Berkeley.

Investigating the Fusion of Comb Jellies

Writing in the journal Current Biology, the team reports that, among other features, the creature appeared to have two “aboral ends”, or backsides.

In addition, Arenas said, the animal had two mouths – something the team had never seen before.

“This led us to wonder if it was the result of two independent animals fusing,” he said. “That same night, we began trying to replicate this observation.”

Experimental Replication of Fusion

The team took pairs of sea walnuts – collected from different sites at different times – and, for each, removed part of the side of the body. Each pair was then pinned together overnight with their injuries touching.

The results revealed that, in nine out of 10 cases, the individuals had fused.

“Once we realised we could consistently reproduce the fusion, we shortened the time, and eventually we found the fusion occurred within a few hours in a petri dish,” Arenas said.

Implications for Understanding Ctenophore Nervous System and Evolution

The team notes it is not the first time the grafting of comb jellies – or ctenophores – has been reported, but they say their experiments expand upon such observations.

Among other findings, the team found when they prodded one side of the fused creature both individuals jerked and contracted, a result that suggests the nervous systems of the pair might have merged, they say.

Arenas said the finding was exciting because very little is known about the ctenophore nervous system.

“Moreover, given that ctenophores are now considered descendants of the ancestors of all other animals, studying how their nervous system works is crucial for understanding the basic principles of neuronal function,” he said.

“Beyond that, our observations suggest that ctenophores might serve as an excellent model for investigating evolutionary processes of self-recognition systems and advancing our understanding of tissue grafting and regeneration in many tissues, including the nervous system.”

Evidence of Nervous System Merger

The idea that the nervous systems had merged was supported by the discovery that, one hour after the comb jellies were paired, their muscle contractions started to synchronise. An experiment involving six fused pairs suggested 95% of contractions within each pair were completely synchronous after two hours.

The researchers found that when they fed fluorescently labelled food to one of the comb jellies, particles passed into the digestive system of the other. The digested waste products, however, were expelled from both anuses in an unsynchronised manner.

Arenas said the study suggested comb jellies had few mechanisms for distinguishing their own tissues from those of others of the same species.

“I am convinced that it provides insight into the molecular mechanism of how single cells recognise themselves when they coalesce to become multicellular animals.”

SDGs, Targets, and Indicators

1. SDG 14: Life Below Water

   • Target 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans.
   • Indicator 14.2.1: Proportion of national exclusive economic zones managed using ecosystem-based approaches.

2. SDG 15: Life on Land

   • Target 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity, and protect and prevent the extinction of threatened species.
   • Indicator 15.5.1: Red List Index.

Analysis

The article discusses the fusion of comb jellies, also known as sea walnuts, when they are injured. This topic is connected to the Sustainable Development Goals (SDGs) related to life below water (SDG 14) and life on land (SDG 15).

SDG 14: Life Below Water

The fusion of comb jellies and their ability to regenerate and graft tissues is relevant to SDG 14, which aims to sustainably manage and protect marine and coastal ecosystems. The fusion of comb jellies demonstrates the resilience and regenerative capabilities of marine organisms.

SDG 15: Life on Land

The fusion and regeneration abilities of comb jellies also have implications for SDG 15, which focuses on reducing the degradation of natural habitats and protecting threatened species. Understanding the mechanisms behind tissue grafting and regeneration in comb jellies can contribute to efforts to protect and prevent the extinction of threatened species.

The specific targets and indicators related to these SDGs are as follows:

Target 14.2: By 2020, sustainably manage and protect marine and coastal ecosystems to avoid significant adverse impacts, including by strengthening their resilience, and take action for their restoration in order to achieve healthy and productive oceans.

The fusion and regenerative abilities of comb jellies demonstrate the resilience of marine organisms and their potential for restoration and recovery.

Indicator 14.2.1: Proportion of national exclusive economic zones managed using ecosystem-based approaches.

While not directly mentioned in the article, the fusion and regenerative abilities of comb jellies highlight the importance of ecosystem-based approaches to managing marine and coastal ecosystems.

Target 15.5: Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity, and protect and prevent the extinction of threatened species.

The fusion and regenerative abilities of comb jellies provide insights into the mechanisms of tissue grafting and regeneration, which can contribute to efforts to protect and prevent the extinction of threatened species.

Indicator 15.5.1: Red List Index.

While not directly mentioned in the article, the fusion and regenerative abilities of comb jellies can contribute to the understanding and assessment of threatened species, which is measured through the Red List Index.

SDGs, Targets, and Indicators

Source: theguardian.com