A bloom of Comb Jellies drifts by underneath the water surface. These free-floating gelatinous animals that drift through the ocean's water column and are not Jellyfish. Jellyfish are completely different animals belonging to another phylum, the Cnidaria. Comb jellies belong to the phylum of Ctenophores.
The limited locomotion of comb jellies is generated by eight rows of hair-cilia, known as combs, that beat in coordinated waves. These strokes also generate iridescent light waves, which is the phenomenon of certain surfaces appearing to gradually change colour as the angle of view or the angle of illumination changes, as seen in soap bubbles. This phenomenon is not bioluminescence.
However, because of their limited locomotion, comb jellies are classified as zooplankton and are at the mercy of the ocean's currents.
Comb jellies consist of a mass of jelly without intestines, lungs, or stomach. Instead, oxygen and nutrients are passed directly through the gastrodermis, the inner epithelial layer of Ctenophores, or even through the epidermis, the layer on the outside of the animal. They are made up of 95% water.
Their transparency means that comb jellies hide in the water column, one of their best defences against potential predators. Turtles and jellyfish prey on comb jellies, and they are the Ocean Sunfish’s (Mola mola) favourite food.
Comb jellies are predators and prey on a number of planktonic organisms, including copepods and fish larvae.
The alien appearance of these primitive animals reminded me of a sentence in the song "Eve of the War," the opening piece from the British 1978 album, Jeff Wayne's Musical Version of The War of the Worlds; "The chances of anything coming from Mars are a million to one, he said… but still, they come." I thought it was a very good match with the thousands of alien-looking comb jellies drifting by over our head while performing a safety stop at the end of our dive.
Filming these almost transparent creatures underwater was a somehow surreal experience and presented me with some challenges. Their delicate, gelatinous bodies pulsate gracefully as they move through the water, which could not be disturbed by the exhaled burst of bubbles coming from my regulator, as this would ruin the underwater footage.
Adding to this challenge was the fact that I wasn't able to really see these creatures through my viewfinder as the sun-lit water surface sometimes made them almost invisible. I had to turn a few times around to find the perfect angle to film these drifting gelatinous animals.
After filming, this footage went through a series of corrections in post-production; boosting the blue of the water column and adding a bit of contrast was necessary to make these comb jellies visible and stand out.
Sometimes, filming plankton can be rewarding, as it creates a sense of wonder. Even after several thousand dives, I am time after time amazed by the incredible diversity of life that exists beneath the waves. From the smallest plankton to the largest whales, the ocean is teeming with fascinating creatures, each with their own unique story to tell.
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