2023-11-12 07:00:08
Starfish are among the most captivating creatures of the deep sea. Their unique morphology has long intrigued evolutionary biologists. Recently, an international team of researchers shed new light on their enigmatic body structure.
Scientists have discovered that sea stars are essentially heads with feet.
Image from Wikimedia Commons
Echinoderms, including starfish, sea urchins, and sea cucumbers, arise from bilateral organisms, symmetrical on both sides. However, they have developed a radial symmetry, with body parts arranged around a central axis. In adult sea stars, five or more arms emanate from a central structure. This transformation has given rise to numerous hypotheses among scientists.
In a recent study published in Nature, researchers challenged previous assumptions. They argue that echinoderms have almost entirely lost their trunk, making their head their entire body. To locate the head and determine the body structure, genetic tests were carried out on the sea star Patiria miniata, analyzing the expression of genes in each area of ​​the animal (An animal (from the Latin animus, spirit, or vital principle) is, according to the classical classification, a…).
Laurent Formery, a biologist at Stanford University’s Hopkins Marine Station, said he sequenced slices of the starfish to create a 3D model of the messenger RNA (mRNA) in the body. The anterior genes manifest all the way to the tips of the arms, while the posterior genes are found at the outer extremities.
Researchers analyzed mRNA from sea stars Patiria miniata to determine the location of their heads.
Image Wikimedia Commons
Even seemingly bilateral echinoderms, such as sea cucumbers, which resemble worms, actually follow a radial plane. Thurston Lacalli, a biologist at the University of Saskatchewan in Canada and not involved in the research, compares the body of a starfish to a disembodied head moving on the ocean floor.
The reason for this development remains unclear. Bilateral plans have proven to be extremely successful over the course of evolution. Echinoderms emerged at the beginning of the Cambrian, a period marked by exceptional diversification of organisms. While the evolutionary forces of that era favored our own bilateral symmetry, a different evolution led echinoderms to become these walking heads on the seafloor.
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