Gulper Eel

The gulper eel (Eurypharynx pelecanoides) is a strange-looking fish that inhabits the deep sea. Its most distinctive feature is its enormous mouth. Their mouth is much bigger than their bodies, making them appear disproportionate. Their mouth opens wide enough to swallow animals much bigger than themselves, almost like it’s hinged. Then, the prey is deposited into a pouch-like lower jaw that resembles a Pelican, which is why they are also called the Pelican Eel.

Their bodies are equipped to accommodate any large meals because their stomachs can stretch. Because of this trait, they are also often referred to as the umbrella mouth gulper.

Gulper eels occur in every tropical and temperate ocean in the world, but because they inhabit the deepest waters, most of the information on record comes from gulpers caught in deep-sea fishing nets.

Three Amazing Gulper Eel Facts

• The stomach of the Pelican eel can stretch to accommodate large amounts of food. However, despite this, they primarily eat small crustaceans.
• Their mouths work like nets when they swim through large schools of shrimp and small fish. In addition to catching prey, their mouths fill with water, which is slowly released through their gill slits.
• Adult males have larger eyes and olfactory organs once they sexually mature, while females don’t change. Males need these changes for reproduction because it helps them detect the pheromones released by females.

Classification and Scientific Name

The Gulper eel’s scientific name is Eurypharynx pelecanoides, and they belong to the Order Anguilliformes. They are also known as Apodes, which means “limbless,” because they don’t have protruding fins.

They are members of the Eurypharyngidae family, which are deep-sea fish that have huge mouths. Gulper eels’ mouths are so big that they can swallow prey bigger than themselves.

While they have large heads, their bodies taper down into a very narrow tail region. These eels live at depths of  6500 feet, so it’s thought their large mouths are an adaptation to the scarcity of food at those depths.

Contrary to popular belief, Pelican eels are not large fish and rarely exceed 24 inches in length.

Appearance

The gulper eel is easily distinguished from other eel species because of its large mouth. However, there are other characteristics that set it apart.

Their tiny pectoral fins are so small that they are hardly visible. In addition, gulper eels have really small eyes, which researchers believe evolved to detect faint traces of light instead of forming images. They also have elongated, whip-like tails.

Their long tails end in a light-producing organ called the photophore. This organ glows pink and occasionally flashes red. This is a trait they use for hunting purposes because they are not very fast swimmers, so instead, they make the prey come to them.

Once their prey is close enough to their massive mouths, they will snap them up. They vary in length from 3 to 6 feet and are generally dark green or black in color. Sometimes they have a white line of dentation on the sides of their dorsal fin. The Gulper eel weighs around 20 pounds.

Behavior

Pelican eels go by many names, but the most fitting is the umbrella-mouth gulper because of the way their mouths blow up, creating a net that scoops up small fish or squid.

This balloon-like capacity is really beneficial for opportunistic feeders. Without this function, the gulper’s tiny teeth would never be able to do the job alone.

Although their mouths give them a fierce appearance, they are relatively weak hunters. Gulper eels have incredibly small eyes compared to other deep-sea species. So, they have to rely on their photoreceptors located at the tip of their tail to lure in prey.

In addition, they are not very good swimmers because of their whip-like tails and lack of pelvic fins. This could be why these mysterious creatures remain at depths of 3,000 to 6,000 feet. These eels spend most of their time drifting around the deep, but they are not being lazy; they are conserving their energy.

Adult males have larger olfactory organs (which are responsible for smell), which help them locate females. Unfortunately, while this is happening, they start to lose their teeth. Researchers think that this happens because they put all their resources into reproduction. In addition, they believe that gulper eels die soon after mating.

Habitat

Gulper eels inhabit the deep ocean waters at around 3,000 to 6,000 feet. Because the sun does not penetrate that far, the water is pitch black, so they have certain adaptations to help them survive there with minimal food sources.

Diet

Their primary food source is crustaceans. Due to the enormous size of their mouths, they can eat a considerable amount in one sitting, so they often prey on groups of:

• Cephalopods
• Shrimps
• Small Invertebrates

Predators and Threats

Gulper eels are preyed on by deep-sea predators like lancetfish, but don’t have many predators at the depths they inhabit.

They have no significant threats, and they are not consumed by humans. Their population seems stable now, and they are listed as Least Concern on the IUCN Red List.

Reproduction, Babies, and Lifespan

There is very little information about the reproductive habits of the Gulper eel. Just like other eels, when they are first born, they begin in the leptocephalus stage (thin and transparent). Before reaching the juvenile stage, they don’t contain any red blood cells, and their body organs are tiny.

As males start to mature, they begin to change, and their olfactory organs start to enlarge, which in turn causes their teeth to fall out. In addition, male Gulper eels have defined reproductive organs. During reproduction, males’ testes occupy most of the space in their stomach cavity, and the stomach shrinks. However, females don’t seem to change at all once they sexually mature.

Males’ enlarged olfactory organs help them locate the females who release a pheromone into the ocean. Many researchers think that gulper eels die shortly after reproduction. In addition, they only reproduce later in life, which is believed to be a strategy that increases offspring survival.

Lifespan/Longevity

Gulper eels have a similar lifespan to humans and can live up to 85 years old. However, their age depends on their habitat and the availability of food.

Population

Unfortunately, there is no information on the Gulper eels’ population size because their habitat is inaccessible to humans. However, the IUCN has classified the population as stable.