Venomous creatures tweak venom to adapt changing conditions: Israeli study

JERUSALEM, March 5 (Xinhua) -- Animals change their venom several times over the course of a lifetime, adapting the potency and recipe of their venom to suit changing predators and aquatic environments, sources from a new study made by the Israeli Hebrew University said Monday.

For a long time, scientists believed that an animal's venom was consistent over time: once a venomous creature, always a venomous creature, however, sea anemones adapt their venom to accommodate changing prey and sea conditions through a close study of sea anemones, said Yehu Moran, a doctor of Hebrew University's Alexander Silberman Institute of Life Science, who is the leader of the study.

Many animals use venom to protect themselves from predators and to catch prey. Some, like jellyfish, have tentacles, while others like bees and snakes use stingers and fangs to inject their prey with venomous toxins.

Moran and his team studied the Nematostella, a relative of the jellyfish, from cradle to grave, and the study has been recently published in eLife Science Magazine.

Nematostella is sea anemones that belong to the Cnidaria family of jellyfish and corals. They begin their life as tiny larvae and grow into animals measuring several inches long. While in the larvae stage, the Nematostella falls prey to larger fish but once mature, it becomes a predator, catching shrimp and small fish with venomous tentacles, said Moran.

Moran said that they found that while in the larvae stage, sea anemones produce uniquely potent venom that causes predators to immediately spit them out if swallowed. Later on, when the sea anemones grow big and become predators themselves, their venom adapts to their new lifestyle by producing a different kind of toxin, one best suited to catch small fish and shrimp.

Over the course of a lifetime, as the Nematostella's diet changes and it moves from one aquatic region to another, it adapts venom to suit new needs and environment, according to Moran.

"Until now, venom research focused mainly on toxins produced by adult animals," explained Moran. "However, by studying sea anemones from birth to death, we discovered that animals have a much wider toxin arsenal than previously thought. Their venom evolves to best meet threats from predators and to cope with changing aquatic environments."

To track these changes, Moran and his team labeled the sea anemone's venom-producing cells and monitored them over time. The researchers also recorded significant interactions that Nematostella had over their lifetime, first as prey and later as predators.

These findings are significant for several reasons, said Moran.

First, venom is often used in medicines and pharmacological compounds. This study suggests that for animals with a complex life cycle there are many venom components that have remained unknown to researchers since, until now, researchers have only studied venom from adult sea anemones, missing out on the unique compounds that exist in larvae venom. These "new" compounds could lead to new medicines and drugs.

Second, sea anemones, jellyfish and coral play a significant role in marine environment. A better understanding of their venomous output and effect on marine life ecology is crucial.

Most fundamentally, the study sheds more light on the basic mechanisms of Darwinism: How do animals adapt to their changing world and ecological habitats?

The Nematostella, with its changing venom, provides us yet another clue, said Moran. Enditem