It appears there might be a resemblance between the hydra of our times and its namesake from Greek mythology. While the fabled creature could grow as many heads as it liked, the small freshwater polyp has to rip apart its mouth every time it eats and then sew it up again.
The discovery was made by a team of scientists from the San Diego and Irvine campuses of the University of California. Their work consisted of using transgenic and color-coded proteins to track the cells found near the mouths of the hydras. In this way, they were able to determine that the polyps’ mouths were created only temporarily by changing the sizes of the cells. It was previously believed that those were rearranged in the process.
Hydras’ diet includes small invertebrates such as shrimp, which are caught by their poison-barbed tentacles. When they feed, the polyps’ openings on their tubular bodies are formed by tearing skin away. After the meal is done, they disappear completely by being sealed with tissue.
Robert Steele, co-author from University of California Irvine, was the one who created transgenic hydra several years ago. Transgenic hydra is hydra that contains cells from another species. In our current case, Steele transferred red and green proteins to others located in the epithelial cells from both outer and inner tissue layers of the hydra.
In this way, the team was able to discover that these cells changed their shapes radically. The sizes of the mouths can vary on the hydras’ prey, and they appear and disappear in less than a minute. The researchers believe this process is controlled by their nervous systems.
According to Eva-Maria Collins, lead author and biophysicist at the University of California San Diego, when they watched the cells’ shapes closely, they saw that even the nuclei of the cells were deformed, which is astounding.
The team believes that each cell shrinks because the cells’ myoneme fibers are triggered to contract, thus forming a large opening. However, if we were to give hydras a muscle relaxant, these contractions would be blocked, and they could not be able to create new mouth anymore.
As the researchers have pointed out,
“This work illustrates that the structural simplicity and the availability of in vivo labeling techniques make Hydra an excellent model for studying fundamental biomechanical processes on both the cellular and tissue levels.”
Their work is truly ground-breaking and will pave the way for understating both tissue patterning and tissue formation.
Image Source: StudyBlue