In nature news, there have been two major firsts discovered in animal kingdom. In my previous life, I was a biologist, making this post a logical tangent. An immortal jellyfish and a photosynthetic sea slug. It is a banner year for fans of evolution.
1. Immortality: Take It, It’s Yours
The turritopsis nutricula species of jellyfish may be the only animal in the world to have truly discovered the fountain of youth. Since it is capable of cycling from a mature adult stage to an immature polyp stage and back again, there may be no natural limit to its life span. Scientists say the hydrozoan jellyfish is the only known animal that can repeatedly turn back the hands of time and revert to its polyp state (its first stage of life).
The key lies in a process called transdifferentiation, where one type of cell is transformed into another type of cell. Some animals can undergo limited transdifferentiation and regenerate organs, such as salamanders, which can regrow limbs. Turritopsi nutricula, on the other hand, can regenerate its entire body over and over again. Researchers are studying the jellyfish to discover how it is able to reverse its aging process. Because they are able to bypass death, the number of individuals is spiking. They’re now found in oceans around the globe rather than just in their native Caribbean waters. “We are looking at a worldwide silent invasion,” says Dr. Maria Miglietta of the Smithsonian Tropical Marine Institute.
2. Borophyl, or what they aren’t teaching in Texas public schools
It’s easy being green for a sea slug that has stolen enough genes to become the first animal shown to make chlorophyll like a plant.
Shaped like a leaf itself, the slug Elysia chlorotica already has a reputation for kidnapping the photosynthesizing organelles and some genes from algae. Now it turns out that the slug has acquired enough stolen goods to make an entire plant chemical-making pathway work inside an animal body, says Sidney K. Pierce of the University of South Florida in Tampa. Pierce emphasized that this green slug goes far beyond animals such as corals that host live-in microbes that share the bounties of their photosynthesis. Most of those hosts tuck in the partner cells whole in crevices or pockets among host cells. Pierce’s slug, however, takes just parts of cells, the little green photosynthetic organelles called chloroplasts, from the algae it eats. The slug’s highly branched gut network engulfs these stolen bits and holds them inside slug cells. Some related slugs also engulf chloroplasts but E. chlorotica alone preserves the organelles in working order for a whole slug lifetime of nearly a year. The slug readily sucks the innards out of algal filaments whenever they’re available, but in good light, multiple meals aren’t essential. Scientists have shown that once a young slug has slurped its first chloroplast meal from one of its few favored species of Vaucheria algae, the slug does not have to eat again for the rest of its life. All it has to do is sunbathe. “Bizarre,” said Gary Martin, a crustacean biologist at Occidental College in Los Angeles. “Steps in evolution can be more creative than I ever imagined.”