Jellyfish can grow new tentacles - and heads

In an ancient Greek myth, Her­cu­les encountered a many-headed marsh mon­ster called Hy­dra that could re­grow its heads if they were somehow cut off.

Now sci­en­tists from the university fo Veterinary Med­i­cine in Han­no­ver, Ger­ma­ny have found a way to cre­ate many-headed jel­ly­fish by de­ac­ti­vating cer­tain genes in the jelly class hydrozoa.

By shutting down a cer­tain Cnox gene, researchers Wolf­gang Ja­kob and Bernd Schier­wa­ter found that they can gen­er­ate hy­dro­zo­an jel­ly­fish with two heads, both of which func­tion normally and both take in food. De­ac­tiva­t­ion of a dif­fer­ent gene led to even more heads, they added.

The discovery isn't really so surprising. It's old hat to the jellyfish who have been generating multiple heads for 540 million years with without having scientists screwing around with their genes thank you.

The best part of the natural system is that the heads are dis-enjoined
so they don't compete and conflict with one another. Moreover, they can control the number of heads produced by the availability of food and other environmental conditions.

The head-generating process takes place in the early stages of the jellyfishes' development, when it is just a coral-like polyp attached to the ocean bottom. It grows the heads on its stalk, stacking them like dinner plates. When the top head (hydra) detatches itself and flips off like an errant frisbee, the next one grows and in time (determined by the availability of food) it follows the first head into the wild blue yonder.