Seashocker

"The Seashocker is capable of emitting underwater sonar, and these dragons travel in schools or pods, similar to fish and dolphins."

- Fishlegs

The Seashocker is a medium-sized Tidal Class dragon that first appeared in How to Train Your Dragon 2.

Official Description
"Supremely furtive, Seashockers share attributes with many of the the ocean's most extraordinary creature: the morphology of a Manta Ray, the sonar of a dolphin, and the bioluminescence of a deep dweller. Similar to Hideous Zipplebacks, the Seashocker also possess two heads. But unlike their airborne cousins, Seashockers only have one thing on their twin heads: predation. If you ever see their dark fins amongst the waves, it's it's already too late for you - the rest of their pod has already moved in to attack! Being water-based dragons, Seashockers do not breathe fire. Instead, their bites paralyze victims with an electrical charge that stuns even the biggest prey into submission. Perhaps this is the reason why all dragons fear the Seashocker's closest evolutionary relative - the electric eel! Seashockers are wonderful ice-breakers, but not in the conversational sense -- their dorsal fins, comprised of super-dense cartilage, can cut through even the most frigid floes, allowing Seashockers to carve a path to any ice-bound prey."

- Dragonpedia

"A deep diver of the Tidal Class that travels in large groups (or pods). It emits underwater sonar to stealthily detect unsuspecting prey... or overboard Vikings! The mighty Seashocker builds up a powerful charge of electricity that it unleashes on it's opponents in battle."

- Dragons: Rise of Berk

Egg
The eggs of a Seashocker tapers towards its tip, giving it a pointy and triangular shape. They have several lighter spots around their base.

Hatchling to Adult
The Seashocker looks similar to a blue Manta Ray, which is more noticeable when seen in a bird's eye view. It has two heads and has large a wingspan of 15 meters (50 feet) with two small flippers in front of it, giving it the appearance of a blue colored Manta Ray. The dragon also has small spikes lining its spine and the top of its heads. Their dorsal fins are very sharp and dense, functioning as amazingly powerful blades that are capable of slicing thick sea ices and even the most solid floes. Its necks are incredibly short. In total, the Seashocker's body shape strongly resembles that of a Manta Ray, with wings that extend perfectly straight out. This natural arrangement ensures great speed in the air or beneath the waves of an icy ocean.

Titan Wing
Titan winged Seashockers have jaws full of spikes and their body is bright yellow. Furthermore, white stripes streak across their wings and its edges are purple. They have light blue spines on their two necks that merge together to form one row of spines on their backs. They have a cluster of spikes at the tip of their tails.

Firepower
Unlike the majority of the dragon species, the Seashocker possesses a unique ability to generate electrical discharges rather than the usual fire breath. Although it can emit electricity from its mouth, it will be released when it has bitten something, or in a short range just before it nips its target. Their electro-charged bites can take out even the largest enemies. Because of their electro-abilities, rather interestingly, electric eels are regarded as the closest evolutionary relative to the Seashocker, which may be the reason eels are feared by almost all dragons. The episode "The Eel Effect", however, suggests the reason dragons fear eels is because of eel-pox and is completely unrelated to the Seashockers.

As seen in Race to the Edge, Seashockers are able to generate a field of electricity as a protection around themselves by joining their heads together. An electrical current can be produced by the snout of each head. When the electrical current joins together, it generates around an electrical field, similar to how the Skrill does. The energy released creates an electrical force so powerful, that even large creatures like Scauldrons, after being electrocuted, would be ejected away forcefully. It can also apparently eject from itself a human up to approximately 60 feet.

Hunting
Seashockers are also fearsome hunters, similar to Orcas in their lifestyle and intelligence, and are equipped with many weapons including dorsal fins, electric charges, and two heads. Hunting in groups, the Seashocker is an expert in the sneak attack. If you see its fin in the water, then the rest of its pod has already moved in to attack.

Seashockers are often found hunting in packs or pods and have great teamwork. This helps them to take down large prey easily. They have also been seen herding shoals of fish into a Bewilderbeast's mouth by circling around it.

Echolocation
They use their echolocation to locate its prey in deep water like dolphins, porpoises, and whales. The underwater sonar they emit allows them to stealthily detect prey. They use this ability to travel in the deepest depths.

Bioluminescence
The Seashocker also has the ability to glow in deep dark waters where the light doesn't reach thanks to its bioluminescence.

Dorsal blades
Their dorsal blades are very powerful and sharp that they can cut through the thickest sea ice. They are composed of super-dense cartilage, which allows them to cut through floating sheets of ice to get to their prey.

Speed and Agility
Seashockers are fast and agile enough to outmaneuver Scauldrons, as well as to ambush its prey. According to Fishlegs, Seashockers move too fast for the human eye to see them.

Strength
Seashockers are strong enough to pull boats occupied by humans, as well as carry humans and other dragons on their backs, showing no signs of struggle.

Diving
Seashockers are able to dive extremely deep in search of their preferred prey, small, deep-sea fish. In order to do so, it is likely that, like many other deep-diving animals, the Seashocker possesses several specialized features to withstand the pressure of the deep ocean. These features include a heart that can decrease its heart rate, collapsable lungs and ribcage that can reduce air pockets, expel 90% of the air inside of the lungs, and decrease their buoyancy, blood and muscles that can store oxygen, the ability to cut off the flow of oxygen to nonessential parts of the body, the ability to limit movement, and the ability to shut down breathing, digestion, kidney function, and liver function. With these abilities, the Seashocker may be one of the deepest divers of all known dragon species.

Weaknesses
The Seashockers' shocking ability produces an electric pulse that Scauldrons can sense, allowing them to track down and prey on the former. Like many Tidal Class dragons, Seashockers cannot last for a very long time out of water and will quickly dry up. Furthermore, unlike other Tidal Class dragons, Seashockers lack legs and on land are as helpless as a stranded whale. In addition, despite possessing wings, Seashockers are very weak flyers, as their wings are designed to be more like paddles for swimming in water. This is why Valka's Seashockers brought Toothless to the shores of Valka's Mountain and gave him to Sailback instead of flying him up themselves.

Behavior and Personality
"Still, it's a good thing Toothless saw all of this wreckage from above. Otherwise, you might've ended up as that Seashocker's breakfast."

- Hiccup The Seashocker lives in very deep, icy waters, where it can use echolocation instead of sight to hunt prey. It can also use its bioluminescence as an attraction to deep sea fish. But on some occasions, like the dragon's feeding time, Seashockers can appear near the surface where they can help the Bewilderbeast draw fish into its mouth by circling around. In return, some fish are given to them.

Their most remarkable feature would be their teamwork. They often hunt in pods and circle their prey into a tight 'bait ball'. They move swiftly together and use it both to hunt and care for their young. Seashockers will also work together to defend against predators, as seen in "Shock and Awe" where they use their own electrical shocks to drive off a pack of Scauldrons.

Despite a diet mainly consisting of deep-sea fish, Seashockers have been known to scavenge flotsam at sea, even if the 'debris' is a Human or a dragon egg, as seen in Dreamworks Press: Dragons. This behavior is mentioned again in Dragons: Rise of Berk, where it is outright stated that Seashockers of Bloodspilt Bay hunt and kill humans for food. Since the human subject in Dreamworks Press: Dragons is struggling to swim in the water and therefore emitting increased electrical signals, it is possible a Seashocker - like a shark - can be attracted to the human as possible prey in this manner.

Season 2
Seashockers make their first chronological appearance one year before the second film in "Shock and Awe". The first Seashocker is a male that got separated from his pod and ended up in the lagoon of Dragon's Edge. He eventually met and interacted with the Dragon Riders, especially Fishlegs, who was mesmerized by the dragon and bonded with him. The Riders tried to help the Seashocker return to the open ocean, but several Scauldrons tracked down and hunted the Seashocker through the lagoon. Fishlegs came to the Seashocker's rescue by joining both heads together, generating an electrical field that pushed the Scauldrons back. Eventually, more Seashockers came to the rescue, using their electrical shocks to chase away the Scauldrons, and they all swam back into the ocean.

Season 4
In "Dire Straits", Ryker and Viggo had a pair of Seashockers pull their dinghy in order to escape the Dragon Riders who have just successfully freed a chained Submaripper.

Season 6
Many Seashockers were summoned by the Berserker Bewilderbeast during the final battle in "King of Dragons, Part 2".

How to Train Your Dragon 2
When Toothless is dropped into the ocean, Valka's Seashockers come from the depths and take him under their wings for protection. They take Toothless to the shores of the Dragon Sanctuary, where he was picked up by Sailback, while Clawlifter took Hiccup.

During feeding time, three Seashockers can be seen circling a group of fish, herding them into the Bewilderbeast's mount, who then spits the fish everywhere to feed the other dragons.

How to Train Your Dragon: The Hidden World
Several Seashockers can be seen splashing around the waters of the Isle of Berk as the Dragon Riders return from one of their rescue missions.

Seashockers are among the myriad of dragons that reside in the Hidden World.

The Serpent's Heir
Several Seashockers appear along other Tidal Class dragons that offer tribute to Toothless, their new alpha. The Twins decide to ride two of them, whom they later name Soaky and Wetty.

Dreamworks Press: Dragons
A Seashocker briefly appears in this game. It is seen swimming among the wreckage of the ship carrying the player and a mysterious dragon egg. Eventually, it notices the player and the egg and is about to attack them when Hiccup and Toothless arrive and chase it off, saving both the player and the egg.

Dragons: Rise of Berk
The Seashocker appeared in this game after the second film aired. Valka's Seashocker, Covecharger, Wavewight, Rane & Shyne and Bolt & Float also became available.

School of Dragons
Seashockers are mentioned in a Stable Quest called "Rising Shockers". The player can send non-active dragons from their stables to complete missions for points and rewards.

"Sea Shockers have risen up from the depths and must be diverted away from trade routes."

- School of Dragons

A school of Seashockers is also mentioned in the quest log, which shows what the dragons have been doing during the quest.

As of March 2018, a NPC Seashocker was seen in the Expansion "Wrath of Stormheart" as a dragon of Nikora Stormheart.

Dreamworks Dragons: Dawn of New Riders
The Seashocker is mentioned indirectly in this game. The player-controlled character Scribbler can find special treasure, including the "Sea Shocker Blade" which can be used to upgrade Scribbler's axe.

Trivia

 * The Seashocker was originally called Oceanzap.
 * The Seashocker shares many similarities with the Sharkworm from the books.
 * So far, the Seashocker is the only dragon with more than one head that is not a Mystery Class dragon. Furthermore, it is the first and only Tidal Class dragon to have more than one head.
 * It is claimed that the electric eel is the Seashocker's closest relative: an odd statement, as it would imply that the Seashocker is in fact a fish and not a reptile like other dragons (and as such would be unrelated to other dragons).
 * Similar to the Hideous Zippleback, its trademark attack requires a tandem between both heads: the heads seem to produce opposite charges and bringing them together generates an electrical pulse.
 * The Seashocker's name is most likely derived from the sea because it lives in water, as well as the fact that it can shock anything in water with its electrical bite.
 * The Seashocker is the second dragon known to use electricity as a weapon, with the first being the Skrill.
 * Seashockers slightly resemble Strafe, a Dinobot from Transformers: Age of Extinction.
 * While the chart shows the Seashocker as a large dragon, it is actually more of a medium-sized dragon, about twice as long as a Night Fury.
 * Although Seashockers are known to only eat deep-sea fish and rarely surface, they have been seen herding fish at the water surface in the second film.
 * Scauldrons are the Seashockers' natural predators.