NHK’s Deep Ocean team succeeds in capturing new behavior of the mysterious deep sea creature coelacanth

NHK’s “Deep Ocean” team, which is known for its success in capturing on film the Giant Squid in 2012,  has brought us various scoops from the deep sea. This time, teaming up with ZDF/ARTE and OceanX along with Dr. Masamitsu Iwata and Dr. Kerry Sink, the team headed to the sea of Indonesia in hopes to  unravel the ecology of the mysterious and ancient phantom fish.  

The coelacanth, long believed to have perished alongside the dinosaurs, astonished the world when a  fishing vessel fortuitously hauled one up off the coast of South Africa in 1938. Dubbed a "living fossil"  due to its unchanged form over 400 million years, the coelacanth has captivated researchers globally.  

This ancient fish is considered to hold significant importance in unveiling the secrets of the evolutionary  transition from sea to land, which is thought to have occurred around 400 million years ago. Despite  numerous studies, the coelacanth's elusive deep-sea habitat and nocturnal nature have shrouded its  detailed ecology in mystery. 

In order to fully observe the coelacanths’ behavior, NHK’s research and planning for the filming started  six years ago. The project developed a special ultra-high-sensitive 8K deep-sea filming system that  enables long hour filming and mounted it on a transparent dome-shaped submersible which was used  when filming the giant squid.  

In the summer of 2024, with a special permission from the Indonesian government, NHK, alongside  researchers from Aquamarine Fukushima (an aquarium and research center for conservation) and other  global coelacanth experts, conducted an unprecedented filming expedition aboard the OceanXplorer, the  world’s most advanced research and media vessel. Utilizing multiple submersibles, they undertook the  world's first 72-hour continuous filming, observing the depth of the sea day and night without  interruption. 

Off the coast of Sulawesi, at a depth of approximately 160 meters, they found a group of coelacanths  congregating in the shadows of an underwater cliff. Previous observations had not revealed any  behaviors indicating awareness of other individuals. However, in this expedition, the team was able to  document numerous instances of interactions between coelacanths. These interactions were observed  between individuals presumed to be male and female, as well as between males, suggesting a connection  to reproductive activities.This is the first time in the world for footage of coelacanth behavior possibly  linked to reproduction to be filmed and it marks a significant step forward in understanding the  reproductive behavior of these ancient fish. 

Furthermore, analysis of the 8K high-definition footage revealed the flexibility and large range of motion of the coelacanth's muscular fins. Experts highly value this finding as it provides crucial insights into  how our distant ancestors might have used their muscular fins during the evolutionary transition from water to land around 400 million years ago. Future analysis is expected to shed light on animals’ water to-land evolution. 

The currently developed documentary “Deep Ocean: The Kingdom of the Coelacanth,” which is a co production with ZDF/ARTE and OceanX, in collaboration with the Coordinating Ministry of Maritime  Affairs and Investment (CMMAI) of Indonesia, will again be narrated by Sir David Attenborough. The  documentary aims to uncover the secrets of how coelacanths survived extinction and have thrived in the  deep sea, offering a glimpse into their remarkable resilience. 

LC