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28. Yellowbarred Jawfish (Opistognathus randalli)



Subject:

The Yellowbarred Jawfish (Opistognathus randalli) is a fascinating fish species that inhabits the shallow coral reefs of the western Pacific Ocean and is quite common on the reefs of the Coral Triangle. They are usually found in the sandy and rubble patches on the edges of the coral reefs. Despite being relatively small in size, 10cm/4inch, these fish have several interesting characteristics that make them stand out from other fish species.


There is another species in the same family, the Giant Sawfish (Opistognathus rhomaleus), that lives in the Eastern Central Pacific Ocean (from the Sea of Cortez/Baja California to Costa Rica) which grows up to 50cm/20inch.


One of the most notable features of Yellowbarred Jawfish is their unique reproductive behaviour. Unlike many other fish species, the males, marked by a bright yellow/orange spot on their upper iris, take care of the eggs and are mouth-breeders. This means that after fertilisation they keep the eggs in their mouths for up to a week or so until the eggs hatch. This is a fascinating adaptation that has evolved to protect the eggs from predators and ensure a higher chance of survival for the offspring.


Underwater videographers and photographers have captured footage of these fish carrying their young in their mouths, providing insight into this unique reproductive behaviour.


Males also frequently engage in jaw locking combats to defend their territory or in an attempt to evict rivals and confiscate their burrows.


Yellowbarred Jawfish are also known for their impressive burrowing abilities. These fish will spend a significant portion of their time constructing and maintaining elaborate burrows in the sand or rubble on the ocean floor. The burrows, reinforced with pieces of broken off coral and small stones, serve as a safe haven for the fish, protecting them from predators and providing a place to rest and hide.


Interestingly, Yellowbarred Jawfish were only recently scientifically described in 2009 by Smith and Vaniz and named after Dr. John E. Randall. Prior to this, the fish was already known as Yellowbarred Jawfish but was laking a scientific latin name. The name Opistognathus comes from the Greek word “opisthe” which translates to “behind” and “gnathos” meaning “jaw”.


The unique characteristics of Yellowbarred Jawfish have made them a popular subject for underwater videographers and Underwater photographers alike. Underwater videography provides a window into the fascinating world of these fish and allows us to better understand their behaviour and interactions with their environment. Scuba divers can also observe these fish in their natural habitat, but must take care to avoid disturbing their burrows or causing damage to the fragile reef ecosystem.


The individual in this clip which was filmed in the Balinese waters of Indonesia, leaves his den to go and take a big bite of… gravel. Once returned to safety he spits out what he doesn’t need.


Technique:

Sometimes it’s good to just to let the animal leave the frame while filming. A shot of the Jawfish leaving and returning to his den is nice in itself, the spit was an unexpected little bonus.


Filming location:

This short underwater videoclip has been filmed in Bali, Indonesia 🇮🇩


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