Jellyfish - use thread painting, transparent overlays, tulle - and multiple jellyfish.
From Wikipedia - The siphonophores, are an order of the Hydrozoa, a class of marine invertebrates belonging to the phylum Cnidaria. Although a siphonophore appears to be a single organism, each specimen is actually a colony composed of many individual animals. Some siphonophores superficially resemble jellyfish, like the dangerous Portuguese Man o' War (Physalia physalis). With a body length of 40–50 m, another species of siphonophore, Praya dubia, is one of the longest animals in the world.
Blaschka’s Glass Models Photographed by Guido Mocafico | The Dancing Rest http://thedancingrest.com/2014/10/13/blaschkas-glass-models-photographed-by-guido-mocafico/
A deep-sea chimaera—a cartilaginous fish related to sharks—seen by the Little Hercules in the Sulawesi Sea. Its snout is covered with tiny pores capable of detecting perturbations in electrical fields generated by living organisms. Image courtesy of NOAA Okeanos Explorer Program.