A locally based underwater photographer Joe Blasy caught one of the beautiful near transparent box jellies - with its long trailing tentacles - on camera last month (April) and posted the videos on YouTube.
The DMCR has erected signage at 11 points on Phuket's west-coast beaches, giving information on the types of jellyfish that may arrive in Phuket's waters, and advice on first aid.
A second video by Mr Blasy, taken in March, also off Kata Beach, can be seen here.
He noted, "To be fair it should be mentioned that I have shown these videos to the Phuket Marine Biological Center and several other jellyfish experts abroad. All agree they are box jellies.
"However the lethality of this particular species cannot be determined without examining a specimen. Many box jellies are no more venomous than an average jellyfish."