It depends on the marker you want to amplify! If you are trying to amplify the DNA barcoding sector (COI), I suggest you use the Folmer primers - LCO1490/HC02198.
I already follow Folmer primer for COI. some species especially Chrysaora could't get result by the use of this primer. I am trying to repeat amplification with this primer to confirm better result.
I am mistaken in any step of isolation. Because few samples of Pelagiidae species DNA isolated earlier with good result. I have extracted DNA from the tentacles, bell margin and gonad using (Orgin) Marine DNA kit. Please give me some suggestion to get a good result.