Shadow Leviathan

"Proceed with caution. A leviathan class creature is near." ― PDA

The Shadow Leviathan is a species of Leviathan-class predator found in the Crystal Caves and the Fabricator Caverns. It is the main threat of these cave systems and it will relentlessly hunt down its prey.

A total of four Shadow Leviathans can be found in Sector Zero, two in the Fabricator Caverns and two in the Crystal Caves.

Appearance

The Shadow Leviathan has an elongated black body with smooth skin and twin rows of 37 small red spots running from behind the head to just before the tip of the tail. Below each row of red spots is a shorter row of eight circular gill pores that run down the side. The head is composed of a triangular shovel-like structure featuring three dark eyes with jet black pupils ringed with bright red on each side. The creature's mouth is located on its underside just behind the head: it is a glowing blue tone, and lined with curved teeth resembling a ribcage. The mouth appears to pass food directly into the creature's stomach.

Seven pairs of jointed clawed appendages run down the sides of the mouth. These have spines along the inside edge to assist in securing prey. Seven more pairs of these appendages can be seen running down the body, decreasing in size as they get closer to the tail to the point that the final three pairs are little more than a small spine. This gives the impression that these grasping appendages once served as walking limbs in a distant bottom-dwelling ancestor, but have since been repurposed into their current form.

Propulsion comes from the large fins on the rear portion of the Shadow Leviathan's body. Though lacking a tail fluke, a large fin is present around halfway down the body on both the dorsal and ventral sides, the ventral fin having smaller fins in front of and behind it. The tail ends with a red point.

Design

The tail portion of the body is very similar in appearance to the black ghost knifefish and the row of holes on the body resemble the gill openings possessed by lampreys. The mouth and mandible design was based on the heads of arrow worms. It also bears a striking overall resemblance to aegirocassis, with its oblong proboscis, hanging feeding appendages, and many bilateral limbs.

Behavior

The Shadow Leviathan will grab the player’s Seatruck or Prawn Suit to attack, pulling the vehicle into its mouth dealing damage until it is released. When the Seatruck is in its mouth, the Shadow Leviathan will spray a bright blue acid onto the windshield. If the Shadow Leviathan attacks the player under 75 health, a cinematic death scene will instead play consuming them whole.

Shadow Leviathans do not attack small prey fish such as the Red Feather Fish, but will attack most hostile fauna. This includes the Brute Shark and the Chelicerate, it is unknown if they are prey to this colossal creature. Due to the Shadow Leviathan commonly not targeting smaller Fauna, it is recommended to proceed with caution when entering its territory, as the Shadow Leviathan will likely attack the player immediately on sight.

If the player is being pursued, it is recommended they take cover in a fissure or among the biome's Large Morganite Formations where the Shadow Leviathan cannot reach them. It will usually give up after a short time, though it may take a while to return to its usual patrol path afterward. Shadow Leviathans do not respawn upon being killed.

Databank Entry

This is a massive 60m+ leviathan that appears to be the odd convergence of several evolutionary offshoots.

• Shovel-like head: The streamlined head of the shadow leviathan helps it slice through the water as it approaches its prey. Beneath its smooth skin is thick head plating that is used as a battering ram to ward off competing Shadow Leviathans during mating season.
• Segmented legs: The legs are covered in a thick segmented exoskeleton similar to an arthropod. The leviathan’s legs are used less for propulsion - which is left to its blade-like tail - and more for hunting prey. The thick legs fold open over captured fauna like a cage, while the strong exoskeleton protects the tissue beneath from damage as the leviathan feeds.
• Bioluminescent digestive tract: The Shadow Leviathan’s mouth leads directly to its digestive tract, which secretes a highly acidic compound onto captured prey. This bioluminescent cavity attracts light-seeking phytoplankton, which in turn draw in larger fish.

Assessment: Extreme threat - Avoid at all cost.

Source: Scan

Sounds

• Attack
• Chitter 1-6
• Prawn suit attack start/end
• Prawn suit attack joystick loop 1-4
• Prawn suit attack metal loop
• Post-death roar
• Aggro roar
• Roar start
• Seatruck attack start/end
• Seatruck attack joystick loop
• Seatruck attack metal loop
• Seatruck attack water loop 1-5
• Out-of-vehicle attack
• Fast swim 1-6
• Swim growl 1-4
• Patrol swim 1-6

Gallery

Side view

Front view

Dorsal view

Bioluminescence

Bioluminescence, front view

Size comparison with the player

A Shadow Leviathan in Crystal Caves

Swimming next to a Large Morganite Formation

A Shadow Leviathan in Fabricator Caverns

View from below

Death cinematic

Shadow Leviathan shown attacking the Seatruck

Concept Art by Alex Ries

Final concept

Front view

Near-final concept

Earlier version of final

Earlier version

Alternate mouth designs

Alternate design

Intermediary design

Intermediary design, mouth closed

Two scrapped alternate designs

Another scrapped alternate design

Scrapped alternate design choice

Similar scrapped design

Similar scrapped design variant

Head shots of scrapped design

Head shots of scrapped design variant

Older concept

Early sketches

Early sketches variant

Early sketches variant 2

First concept

Model from Sketchfab

Trivia

• The Shadow Leviathan has the most known concept artwork of any fauna species in Subnautica, with 21 pieces having been released featuring 27 different designs, with several more remaining unreleased as evidenced by the numbering of the released pieces.