Probably the most impressive jellyfish invasion began in 1982 when a few, small baseball-sized hermaphrodite jellyfish got into the Black Sea, probably in the ballast water of a visiting freighter, found conditions to their liking, and began to reproduce in a major way. In order to explore the structure of the Jellyfish galaxies in 3D and calculate the timescales of their transformation, Dr. Callum Bellhouse of the University of Birmingham in the U.K. created interactive models that can also be experienced in virtual reality.
Although more work is needed to improve the maneuverability of robots that use live animals, in this work, we have constructed a biohybrid robot that is 10 to 1000 times more energy efficient than existing swimming robots reported in literature, by integrating microelectronics in live jellyfish.

Take precaution before going in the water by checking with the local life guards, who will readily tell you of any hazards to be aware of. Pack a small jar of white vinegar - available at grocery stores - in your beach bag so you're not caught empty handed in the event of a jellyfish sting.
The largest is the lion's mane jellyfish (Cyanea capillata), which can have a bell over six and a half feet in diameter and weigh up to 440 pounds; the smallest is the Irukandji jellyfish, several species of dangerous jellyfishes found in tropical waters, which measure only about two-tenths of an inch and weigh well under a tenth of an ounce.

A jellyfish's tentacles contain venom that, at worst, can destroy the cardiovascular system in just a few minutes Poisonous jellyfish are most prevalent in waters off the coast of Australia, so swimmers stung by jellyfish in this region should consider seeking prompt emergency care.
Also as I continued to watch, National Geographic, they stated that this jellyfish is blooming out of control because of us. Due to polluted waters, there are highly concentrations of the pollutants that they need to multiply, as they do. This is happening in the "Black Sea, Mediterranean Sea, as well as the Chesapeake Bay, etc.

gallumboverde are compelling model organisms for more energy-efficient underwater vehicles because of their low cost of transport (COT; or mass-specific energy input per distance traveled) ( 1 ). Existing robotic mimics of swimming animals composed entirely of engineered components can achieve velocities comparable to natural animals, but with orders of magnitude less efficiency than jellyfish ( 2 - 7 ). In contrast, biohybrid jellyfish robots that incorporate live animals offer potential advantages that address the grand challenges of robotics ( 8 ), by using the jellyfish structure and muscle for actuation, solving the power requirements by leveraging natural feeding behaviors to extract chemical energy from prey in situ, and recovering from damage via wound healing processes that are inherent to the animal.
Cnidarian (Jellyfish, Cubomedusoids, Sea Wasps, Portuguese-Men-'-War or Bluebottles, Hydroids, Stinging Corals, Sea Anemones, etc.) tentacles are armed with millions of stinging capsules (nematocysts) which, triggered by contact or chemicals, evert stinging hairs that penetrate the skin, producing lines of painful, irritant weals.