How ‘Benjamin Button’ jellyfish reverse age to survive

Sub : Env

Sec: Species in news

Context:

Reverse development is the phenomenon in jellyfish-like organisms, where certain species can revert to an earlier stage of their life cycle to survive stressful conditions.
This process has been noted in the immortal jellyfish (Turritopsis dohrnii) and, more recently, in comb jellies (Mnemiopsis leidyi).

Reverse development:

In the 1980s, researchers Christian Sommer and Giorgio Bavestrello accidentally discovered the remarkable ability of Turritopsis dohrnii to revert to an earlier life stage when faced with stress, such as physical damage or environmental changes.
Normally, adult jellyfish (medusae) release planulae (larvae) that develop into polyps, which then grow into new adult medusae.
However, in stressful conditions, Turritopsis dohrnii can revert from the adult (medusa) stage back to a polyp or even a larval stage, this phenomenon is called reverse development.

Reverse Development in Comb Jellies:

A new study reveals that the comb jelly can also undergo reverse development when stressed.
To study this phenomenon, the scientists subjected the comb jellies to two types of stress: prolonged starvation and physical injury or lobectomy (cutting the adult lobes).
The researchers found that animals subjected to lobectomy had a significantly lower mortality and higher success rate in reverting to earlier developmental stages (40% reversal success) compared to those that were starved (14%).

Key differences:

Immortal Jellyfish reverts into a colony of polyps rather than a single larval organism. This makes it difficult to track the development of a single specimen.
Comb jellies, on the other hand, reverts to a single larva, allowing researchers to more easily trace and study the life cycle of an individual organism.

How reverse development helps to survive harsh conditions:

After undergoing stress, comb jellies reverted to the larval cydippid stage. In this stage, the creature is simpler and requires fewer resources to survive.
Once provided with sufficient food, the larvae could grow back into full adults.

Ecological implications of Reverse Development:

Mnemiopsis leidyi is a highly invasive species, and its ability to reverse development may contribute to its ecological impact.
The species has been linked to the collapse of fisheries in the Black Sea in the 1990s.