Jellyfish

Digging deep into jellyfish genomes

A hard look at soft jellyfish has revealed more than a few surprises.

When biologists from Hong Kong, the US and Canada decoded the genomes of two species common in Asian waters, they identified genes that encode sesquiterpenoid hormones, previously thought only to be contained in arthropods.

These hormones are important in regulating metamorphosis in insects, such as moult and wing growth of the silkworm.

Since jellyfish also undergo metamorphosis during their lifecycle, the researchers say, their finding would help explain how the species undergo the transition between developmental stages, and the change of reproduction method during their lifecycle.

The flame jellyfish is a delicacy in parts of Asia. Credit: Chinese University of Hong Kong

The research was led by Jerome Hui Ho Lam from the Chinese University of Hong Kong.

The team sequenced the genomes of the Amuska jellyfish (Sanderia malayensis) and the edible Rhopilema esculentum, better known as flame jellyfish and regarded as a delicacy in China and some parts of South East Asia.

Both are scyphozoans, sometimes referred to as “true jellyfish”, which include the species most commonly seen by swimmers – too commonly during all too frequent jellyfish blooms.

“Scyphozoans play significant ecological roles from surface waters to the deep sea, as an important part of the oceanic food chain, and they are found in every major ocean in the world,” the researchers write in a paper in the journal Nature Communications.

They report that, along with the sesquiterpenoid hormones, they made several unexpected findings in relation to the genome architecture and evolution of the species, including identifying the distinct organisation of the homeobox genes (which regulate development in multicellular organisms) in both jellyfish.

This, they say, helps provide a clearer picture of how cnidarians (which include jellyfish and a number of other marine species) and bilaterians (animals having bilateral symmetry) began separately evolving from a common ancestor of more than 600 million years ago.

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