Although jellyfish do not have the visual acuity of fish, the increased water content in their tissues has given them aoversized gelatinous body that makes them extremely effective hunters. This is the conclusion reached by researchers from the University of Oviedo and the Oceanographic Center of Gijón of the Spanish Institute of Oceanography (IEO), in collaboration with the Roger Williams University of the USA, who have revealed theevolutionary keys of jellyfishin a job published by the magazineScience.
It is the first theory, based on experimental data, that explains the evolutionary strategy followed by jellyfish and the delicate balance that links them to fish, with whichcompete on equal termsdespite being the first blind, slow and ancient predators. “While fish have developed great visual acuity to detect prey, jellyfish rely on a primitive system based on direct contact with prey. The key to their success is that by increasing their body size,displace more water and drag more prey into their tentacles“, says José Luis Acuña, co-author of the work. The strategy is effective as long as the swimming speed of the jellyfish is slow enough.
In order to assess the efficacy in obtaining food, the researchers took into account the different body density of organic matter from jellyfish and fish; and they observed that, when organisms with the same amount of organic matter are compared, the predation rate is the same in jellyfish and fish. Research confirms that overexploitation of fish stocks can lead to a change in the marine ecosystem that favors the expansion of jellyfish over fish. Jellyfish are as effective predators as fish, so “are prepared to play the role of fish in the face of overexploitationor any other damage suffered by the populations of the latter “, assure the authors of the work.
