Subject:
This is one of those strange, alien-like animals that is sometimes encountered on a scuba dive, and nobody really knows what it is.
It is often understandably confused with flatworms or nudibranchs due to its size, resemblance, and habitat. As a matter of fact, it is neither of them, but it is a Crawling Comb Jelly (Coeloplana meteoris), also referred to as a benthic platyctene or a benthic comb jelly. Benthic comb jellies are animals belonging to the Ctenophora, a phylum of marine invertebrates commonly known as comb jellies.
Crawling Comb Jellies are found on the substrate in contrast to most other comb jellies, which are pelagic and thus venture into the water column. Most benthic comb jellies live in association with echinoderms like sea stars, urchins, and sea cucumbers. The Crawling Comb Jelly is probably the only member of the phylum Ctenophora that lives freely on the sea bottom and without a host.
These gelatinous animals catch their prey by releasing two flexible structures, up to 60cm/2ft long, covered with sticky cells called colloblasts, from their two bump-like muscly appendages on top of their body, which contains the mouth and pharynx or throat. When small prey is caught in these adhesive-covered tentacles, the catching device is then pulled in like a fishing line and brought to the mouth to be consumed.
All members of the phylum Ctenophora are hermaphroditic, being both male and female. Adults produce eggs that develop into planktonic juveniles called "cydippid." There is no larval stage for these alien-like gelatinous animals. Once hatched, the juveniles grow gradually until they have reached adulthood.
The Crawling Comb Jelly is found in relatively shallow waters throughout the entire Indo-Pacific area. It prefers muddy and sandy substrates and is most active during the night.
Technique:
These underwater images were filmed more than 12 years ago in Bali, Indonesia, on a shallow muck dive site on the northern shores called Puri Jatti. At that particular moment in time, most cameras for underwater videography were recording in HD 1910 x 1080. 4k existed already but was still enormously expensive, and many editing programs were unable to cope with all the data of 4K footage. Today, most cameras can film in 4K, and in a certain way, 4K has become the new standard.
The quality of this underwater video footage is not too bad, but to assure a good final product, I used a few easy tricks. In post-production, I created two layers of each shot. In the top layer, I cut out the animal itself and sharpened the image. The "sharpen" tool is found in your effects browser; all editing software programs have this feature. When adding this effect, make sure you do it in a subtle way; otherwise, it creates a lot of unwanted contrast. On the lower layer, I added a "Gaussian blur" effect. Also here, I used it in a very subtle way. The contrast between the sharpened animal and the slightly blurry background made the Crawling Comb Jelly pop out. To increase the combined effects even more, I added a vignette.
Filming location:
This short underwater videoclip has been filmed in Bali, Indonesia 🇮🇩
More about this topic:
For an in-depth description about other comb jellies please visit vlog posts 83 or click on this link: https://www.beyondscuba.com/post/space-invaders
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