The starlet sea anemone (Nematostella vectensis) is from the Animalia kingdom classified under the phylum Cnidaria. They are tiny, flower-like invertebrates and appear translucent and colorless except for visible opaque white pattern on the column and disk. Its usual habitat is brackish lagoons, brackish ponds, ditches, and salt marshes. The starlet sea anemone is found in the eastern and western coastlines of North America with some occurrence in the United Kingdom. It reproduces both sexually and asexually. It can tolerate high salinity from 2 to upto 52 ppt (parts per thousand) . It has a lifespan of 65 years and feeds by capturing small mollusks and crustaceans with their tentacles-filled with venom and pull the food down to their mouths.
The starlet sea anemones defied the laws of genetics when it sprouted extra limbs. This is because our genetic code is made in a way that we develop two legs and two arms, similar to fishes with their fins and insects with their wings and legs. The sea anemones do not develop in this manner, genetically. Up to now it was unclear what controlled the number of tentacles a sea anemone would grow. The sea anemone can grow new tentacles throughout their life. Since it uses various ways to grow the tentacles depending on which stage of life, it comes in handy when a tentacle is harmed, as it grows one back. To figure this out, Biologist Aissam Ikmi of the European Molecular Biology Laboratory and his team fed a test population of sea anemones for six months. Dr. Ikmi observed a relation between how much they were fed and how quickly the adult stage tentacles appeared.
The group of researchers studied more than 1,000 sea anemones. Sea anemones as larvae have four central buds around their mouth which grow into their first four tentacles. It was understood the growth of tentacles was related to the food available. On reaching adulthood they keep growing as many as 24 but most max out at 16. The scientists fed the anemones a normal diet of brine shrimps, in which it took five days to sprout new buds and another five days for the buds to develop into full grown tentacles. Dr. Ikmi observed how well-fed anemones grew new pairs of tentacles sooner as opposed to when the feeding was slowed, so did their tentacle growth.
To understand what drove the growth of tentacle, Dr. Ikmi searched the literature and found that anemones similarly to other plants, animals and yeasts have a cell signaling pathway which is related to their nutritional uptake to developmental progression. The researchers then blocked this pathway called “target of rapamycin” and observed the sea anemones stopped growing new buds and tentacles even when fed continuously.
Dr. Ikmi commented “There is not one recipe to build a structure”, as he found that tentacles in the adult stage develop differently from the anemones’ first four tentacles. Dr. Ikmi and his team identified the gene responsible for growing these starter buds in muscle cells and using CRISPR (gene-editing technique) created anemones (mutant) lacking the gene. This resulted in maturity of the first four tentacle buds of the mutant anemones. But no extra pair of tentacles were observed even after being well fed as the mutant anemones lacked the gene and were unable to grow new tentacles. Where the gene is active, the muscle cells mark where the next wave of tentacles will develop and neighboring muscle cells activate their own versions of the gene as they develop, producing a ripple effect of new buds across the body of the anemone.
As a sea anemone can live up to 65 years, they need to constantly adapt their body to different environmental conditions. Conditions such as the availability of food, salinity and temperature affects the growth rates and the occurrence of these species. Dr.Ikmi said sea anemones are animals but they react more like plants as they are rooted to one place and hence are always adapting.
References
You may also like: https://shasthrasnehi.com/why-should-we-thank-phytoplankton/
Author
