Megaloplankton are marine planktonic organisms that are larger than 1 m in size. The largest are the jellyfish Cyanea arctica, whose dome diameter reaches 2 m and tentacles are up to 30 m long, and pyrosome colonies, which form a ribbon 1 m wide and 30 m long.

Large planktonic species: moonfish - over 3 m at a weight of 1500 kg, Regalecus - up to 6 m at a weight of over 250 kg, Carinaria cristata up to 50 cm long. Among the large cephalopods there are also planktonic species (Thysanotheuthis spp. mantle length up to 1 m), they prey, passively hovering in the thinness of the water spreading tentacles (some tentacles are equipped with luminous organs that lure prey).

Megaplankton include: multicellulars (jellyfish), combers, salps and pyrosomes, cephalopods, amphipods, pteropods, combers, salps, doliolids.