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Also known as ghost sharks, ratfish are an ancient relative of sharks and rays. This one is Chimaera monstrosa
 

Sharks and their relatives are among the most successful organisms on Earth, with nearly 1,300 species of sharks, rays, and chimaeras currently described from around the globe. Though often associated with tropical or warm water environments, these creatures also inhabit colder regions. In the Northeast Atlantic alone, 137 species have been identified, most of which are deep-sea dwellers residing at depths beyond 600 feet, meaning human encounters with some of these colder-water species are exceptionally rare.

Despite their elusive nature, some deep-water species occasionally venture into shallower waters in very special places. During a 2023 diving trip to Trondheim, Norway, I was fortunate enough to encounter velvet-belly lantern sharks (Etmopterus spinax), blackmouth catsharks (Galeus melastomus), and ratfish (Chimaera monstrosa) at recreational diving depths. Trondheim Fjord offers a unique marine habitat with special conditions that allow these typically deep-dwelling species to be found at scuba depths. The fjord is also home to the world’s shallowest cold-water coral reef, sitting at just 130 feet. We conducted all of our dives from Vangshylla while staying at Skarnsundet Fjordsenter, which is not a dedicated dive center.

The conditions that make Trondheim Fjord special also make it difficult to dive: The water is very cold and dark, and the powerful tidal currents demand careful timing to ensure safe dives. Despite these challenges, the rewards are well worth it. We encountered both chimaeras and blackmouth catsharks as shallow as 50 feet, while the lantern sharks generally stayed a bit deeper, at around 100 feet. We would usually spot at least one of the three species within just a few minutes of diving, thanks to their large green eyes reflecting the light of our dive torches.

Based on knowledge acquired from the local divers, chimaeras can be seen year round, while the sharks are more commonly seen during spring, summer, and autumn. They also advise that the best chance of encountering these creatures is during the transition from low to high tide, around the new moon, and at night.
 

Velvet-Belly Lantern Sharks

• Maximum size: 18 inches
• Habitat: Deep-sea waters—mostly demersal, continental shelves and slopes, typically from 230–6,500 feet
• Diet: Small bony fish, crustaceans, and cephalopods
• Range: East Atlantic—Iceland to Gabon, including the Mediterranean Sea
• IUCN Red List status: Near Threatened

Detail shot of a velvet-belly lantern shark showing the photophore patches (photomarks) on the belly and flanks. It’s these areas that produce light
 

The velvet-belly lantern shark is Europe’s second-smallest shark, capable of attaining a maximum length of 18 inches. This species is aptly named for its velvet-black belly and bioluminescent capabilities, both of which have enabled it—despite its small size—to be successful in the pitch-black depths of the Northeast Atlantic. The light is produced using specialized organs called photophores that are located on both the belly and flanks of shark. These are believed to aid in camouflage by masking the silhouette of the shark from larger predators lurking below (counter-illumination) and possibly also for communication between individuals. Lantern sharks are highly social, often forming large aggregations, hypothesized to cooperate in order to subdue larger prey.

We were incredibly lucky during our dives in Trondheim, as we encountered these sharks on all our night dives. We often saw them in groups, hanging out on the upper slopes of the fjord at around 65 to 100 feet. They are quite inquisitive and not at all skittish, sometimes even swimming between our legs and bumping into us. However, getting good pictures did require some patience since they are quite fast and agile. Their unique coloration can also cause issues getting a good exposure on the animal. Remember to review your images during and after the dive.

Photo Tip: When photographing lantern sharks (and many marine animals in general), switch to red light on your focus or video light as you approach. Red light is less likely to disturb or stress marine animals because it doesn’t penetrate deep ocean depths, making it effectively “invisible” to many marine organisms that cannot perceive the color red. This minimizes interference and allows for more natural behavior, resulting in better pictures. Despite the shark’s small size, wide-angle lenses are great choices because of how comfortable they are around divers.
 

Ratfish/Ghost Sharks

• Maximum size: 5 feet
• Habitat: Deep waters—demersal, upper continental slopes, typically from 650 to 5,500 feet
• Diet: Mostly benthic invertebrates such as crustaceans, bivalves and echinoderms
• Range: Northeast Atlantic and Mediterranean Sea                                                                              
• IUCN Red List status: Near Threatened

Chimaera monstrosa cruising just over the sandy seabed in Trondheim Fjord
 

Chimaera monstrosa, commonly known as the ratfish, rabbitfish, or ghost shark, is one of the more enigmatic creatures of the deep. With its long, whip-like tail, large eyes, and strange body shape, it resembles something out of a sci-fi movie—an alien! Its closest relatives are sharks and rays, although their last common ancestor existed around 400 million years ago. Though sharing a lot of characteristics with sharks and rays, chimaeras are distinct in several notable ways: They have an operculum-like gill cover, teeth that are fused into three pairs of ever-growing plates, and an upper jaw that is fused to the skull. They also swim more like rays than sharks, using their large pectoral fins for movement, gracefully gliding through the water. Of the shark or shark adjacent species in Trondheim, the chimaeras were the most challenging to photograph due to their shy nature. With patience and slow movements, however, the ratfish would occasionally approach closely, seemingly becoming curious about the strange visitors and their lights.

Photo Tip: Typically, chimaeras are initially quite shy, and abrupt or quick movements or loud noises can easily spook them. Staying as calm and still as possible is key for lettitng them get comfortable and approach of their own accord. Chimaeras have a tendency to be incredibly reflective so low strobe power and a good set of diffusers will be hugely beneficial.
 

A curious chimaera approaches the photographer. The rounded structure located between the eyes is a specialized appendage only found in males called a tenaculum, which is unique to chimaeras. It is used in reproduction and features a bulbous tip equipped with many tiny hooks that helps the male securely grasp the female during mating

Blackmouth Catsharks

• Maximum size: 3 feet
• Habitat: Deep-sea waters—demersal, outer continental shelves and upper slopes, typically from 180 to 6,500 feet
• Diet: Small bony fish, crustaceans, and cephalopods
• Range: Northeast Atlantic and Mediterranean and West Africa—from Morocco to Mauritania
• IUCN Red list status: Least Concern

A large blackmouth catshark cruising along the sea floor. Notice its enlarged eyes specially adapted to pierce through the near-total darkness of the deep ocean
 

The blackmouth catshark is a intriguing shark, named for its characteristic black coloring inside its mouth, which actually lines the entire inner body cavity. Its beautiful coloration and intricate patterns provide superb camouflage against the sandy and rubbly substrate. I have to admit that I’ve swum past quite a few of these, which my dive partners can attest to and never let me live down! Virtually nothing is known about the behavior of these animals, but they may be predominantly solitary, as I’ve only ever observed one at a time. These sharks where the rarest encounter that we had, and we only saw them on one of our dives. However, they turned out to be very relaxed and unbothered by our presence and behaved similarly around photographers as the lantern sharks did.

Photo Tip: Blackmouth catsharks are often difficult to find, but fortunately, once located, they are quite a bold species. A photographic approach similar to that for the lantern sharks will also work well with the catsharks. A wide lens and a red focus light will be your best friends for photographing these beautiful little sharks. As with the chimaeras, they are reflective and diffusers will be hugely helpful for proper exposures.
 

Other deep sea animals, such as this spectacular jelly (Periphylla periphylla), may also be encountered when diving in the Trondheim Fjord. Interestingly, these animals deviate from the typical life cycle of most cnidarians by lacking a polyp stage, instead spending their entire existence in the pelagic (holopelagic life cycle)

Final Thoughts

Exploring Trondheim Fjord offers a rare glimpse into the hidden world of the deep sea, providing an unforgettable one-of-a-kind experience. Unfortunately, deep-sea sharks and their relatives are under growing pressure. They are increasingly caught as bycatch, but also retained and even targeted in some fisheries for their meat and oil-rich livers. Their livers are rich in squalene, a compound used in cosmetics and human health products like vaccine adjuvants, despite the availability of plant-based and synthetic alternatives. Shark meat is eaten worldwide—including Europe. While fishing remains the biggest threat to these animals, future plans to conduct deep-sea mining for minerals pose an additional risk to these delicate animals and their habitats. New species of sharks, rays, and chimaeras are continually being discovered. However, with virtually no protection in place to protect these animals, their future remains uncertain.
 

To see more of Elias’ unique underwater work, please give him a follow on Instagram and visit his website, www.eliasneuman.com.