11 Differences Between Eels and Sea Snakes

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11. Type of Animal

Eels are a specific type of elongated fish and can be found in marine and freshwater environments. Sea snakes are reptiles and they are only found in marine environments.

They are much flatter, in the vertical sense, than a snake. In addition, these fish’s heads tend to be longer and sharper. Eels also have fins, which sea snakes never have. The fins are often located along the top or bottom of the fishes’ body or protruding from just behind the head.

In the water, sea snakes often look more like a swimming rope, while eels appear more like a ribbon, in shape, texture, and movement.

Eels that live deep in the sea are usually gray or black. Eels that live in tropical areas have bright patterns and colors. However, Color and patterns on the body of sea snakes depend on the species. Alternating rings of various colors (black, red, grey, white or blue) are commonly seen in sea snakes. Some species are uniformly colored.

10. Habitat

Sea snakes are found throughout the coastal waters of the Indian and Pacific oceans. They do not occur in the Red Sea, Atlantic Ocean, or Caribbean Sea. Most sea snakes live in shallow water less than 30 meters (100 feet) deep because they need to surface to breathe yet must seek their prey near the sea floor. However, the yellow-bellied sea snake may be found in the open ocean.

The so-called “California sea snake” like other sea snakes, cannot live in cool water. Below a certain temperature, the snake is unable to digest food. Snakes may be found washed up on shores in the temperature zone, typically driven by storms. However, they call the tropics and subtropics their home.

In the other hand, some eels live in places that have freshwater such as ponds, rivers and lakes. When they are ready to reproduce, they travel, or migrate, to the saltwater of oceans and seas. However, many eels live in saltwater at all times. Eels are found throughout the world. They are bottom dwellers, which means that they usually can be found on the muddy or sandy floor of the river or ocean where they live.

Eels live in shallow waters or hide at the bottom of the oceans in holes which are called eel pits. Eels can swim backwards and forwards, and they can travel on land for short distances.

9. Behavior

Moray Eel

Eels is an ambush predator, spending a considerable amount of time hidden in caves, rock crevices, or coral reefs. When a prey animal passes by, it pounces on it. Depending on the prey type, the eel might wrap itself around it, and crush the victim until it is small enough to be swallowed, or it might tear pieces from the body and eat the prey bite-by-bite.

Eels often appear very menacing, as they almost constantly gape their mouths showing their teeth. However, this gaping is necessary to allow water to be pumped into the oral cavity, and then over the gills. Some eels are territorial. For example, the giant moray can have a territory that extends over several miles.

However, Sea snakes are generally reluctant to bite, and are usually considered to be mild-tempered, although variation is seen among species and individuals. Some species, such as P. platurus, which feed by simply gulping down their prey, are more likely to bite when provoked because they seem to use their venom more for defense. Others, such as Laticauda spp., use their venom for prey immobilization; these snakes are often handled without concern by local fishermen, who unravel and toss them back into the water barehanded when the snakes become entangled in fishing nets.

On land, their movements become very erratic. They crawl awkwardly in these situations and can become quite aggressive, striking wildly at anything that moves, although they are unable to coil and strike in the manner of terrestrial snakes.

Sea snakes appear to be active both day and night. In the morning, and sometimes late in the afternoon, they can be seen at the surface basking in the sunlight, and they dive when disturbed.

8. Conservation status

The European eel is a critically endangered species. Since the 1970s, the numbers of eels reaching Europe is thought to have declined by around 98%. Contributing factors include overfishing, parasites such as Anguillicola crassus, barriers to migration such as hydroelectric dams, and natural changes in the North Atlantic oscillation, Gulf Stream, and North Atlantic drift. Recent work suggests polychlorinated biphenyl pollution may be a factor in the decline.

Sea snakes are not endangered. However, there are some species on the IUCN Red List. Laticauda crockeri is vulnerable, Aipysurus fuscus is endangered, and Aipysurus foliosquama (leaf-scaled sea snake) and Aipysurus apraefrontalis (short-nose sea snake) are critically endangered.

Sea snakes are difficult to keep in captivity, due to their specialized diets and habitat requirements. They need to be housed in rounded tanks to avoid damaging themselves on corners. Some need to be able to exit the water. Pelamis platurus accepts goldfish as food and can survive captivity.

7. Nostrils

Nostrils of sea snakes are equipped with moveable valves that prevent water to enter the nose when they are under the water.

The tubular nostrils spotted on eels are believed to help them detect prey. Having poor eyesight and hearing, they rely mostly on their sense of smell to alert them of prey and other marine animals.

6. Size and diet

Depending on the species, eels can grow to be anywhere between 4 inches to 11 1/2 feet long. However, most sea snakes grow to sizes between 3.9 to 4.9 feet long. Largest sea snake can reach 9.8 feet in length.

Eels are carnivorous, meaning they are meat eaters. They eat a variety of animals such as worms, snails, frogs, shrimp, mussels, lizards and other small fish. They generally hunt for food at night.

Sea snakes are also carnivores and their diet mainly consist of different types of fish, crustaceans, mollusks and eggs of various sea creatures.

5. Gills

Giant Moray Eel

Eels have gills, as most other fish do, and filter air from the water in order to breathe. This means that they never have to go to the surface. Snakes, on the other hand, do not have gills, but lungs. 

Sea snakes can dive to the depth of 300 feet. Most species prefer to dive in shallow water. They are able to spend up to one hour under the water without returning to the surface to breathe. On average, they dive for 30 minutes. This means that, although some of these snakes can hold their breath for an extremely long time, they will eventually have to return to the water’s surface for air.

Sea snakes can survive for more than 10 years in the wild.

4. Mating season

Giant moray eels starting to mate

Mating season of sea snakes depends on the species. Only several species will lay eggs on the solid ground. Most species give birth to live snakes. WOOW! Can you imagine that?

Females give birth once in two year. he gestation period varies wildly, anywhere between 4 and 11 months, and is dependent on a number of factors, including abundance of food, water temperature and the age and health of the female. Once born, the young are on their own; the adults have no parental instincts at all. The number of babies ranges from couple to more than 25. Snakes born in the water may be nearly as large as adults. When mating urges strike, sea snakes can be quite aggressive. This aggression may be between one male and another, male and female or a snake of either sex toward another animal or person.

In the other hand, mating season for eels is a total mystery. They can produce up to 30 million eggs at a time, but their sex lives are still unknown. Eels can take up to 20 years to mature, upon which they’ll swim toward the Sargasso Sea.

Eels are listed as critically endangered by the International Union for Conservation of Nature (IUCN), so we may never know their mating secrets.

3. Senses

Sea snakes flick their tongues to gain chemical and thermal information about their environment. Sea snake tongues are shorter than those of regular snakes because it’s easier to “taste” molecules in water than in air. There is no much information about sea snake vision, but it appears to play a limited role in catching prey and selecting mates. Sea snakes have special mechanoreceptors that help them sense vibration and movement. Some snakes respond to pheromones to identify mates.

As we said in Nostrils section, eels also have remarkably poor eyesight, so they rely largely on their incredible sense of smell when hunting.

2. Scales

Scales of a Faint-banded sea snake

Both have scales, each with different patterns and colors. However, the scales of a snake are much easier to see, and the pattern of these scales is clearly visible to the human eye. The eel’s scales are much smaller and give the animal a smoother appearance, though.

Sea snakes even have a special scale that let them feel movements in the water. They developed a scaly organ on their heads which lets them “see” underwater.

The sensors, known as scale sensilla, are sensitive organs that protrude from scales on a snake’s head. These head-organs facilitate awareness of water movements, but the extent of their awareness isn’t well understood.

So be careful my friend, even the smallest movement will betray you.

1. Poisonous

The most vital difference between eels and sea snakes for humans, however, is that Sea snakes are almost always venomous, whether it is a mild venom or, in many cases, one of the most toxic. The most poisonous one is the Beaked Sea Snake.  Just 3 drops of venom can kill about 8 people! Fortunately, these snakes have short fangs and they are unable to bite through diver’s suits very easily. Other than venom, some sea snakes produce enzyme that induces digestion of the prey from the moment of bite.

They are not likely to bite unless threatened.  Their other methods of defense include to spray a stinky, musky liquid or to poop. Eeeew!!!

Symptoms of sea snake poisoning include headache, stiffness, and muscle pain throughout the body. Thirst, sweating, vomiting, and a thick-feeling tongue may result. Muscle degradation and paralysis ensue. Death occurs if the muscles involved in swallowing and respiration are affected. Because bites are so rare, antivenin is next to impossible to obtain.

Eels, on the other hand, are not venomous, but can deliver a nasty bite if you offer your hand. Further reinforcing the “don’t touch” creed divers should all know well!

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