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Table of Contents
Eels may look like snakes, but they are actually fish. There are over 800 different species of eel. Freshwater eels are known to travel as far as 4,000 miles to breed. Despite its name, the electric eel is not an eel but a knife fish. Eel is a delicacy in some cultures, but its blood is toxic, so it needs to be cooked thoroughly. Keep reading for more interesting facts about eels.
General Facts about Eels
- Eels belong to the order Anguilliformes (aka cousin of the fish).
- Even though the eel looks like a snake it is really a fish.
- They have long, narrow bodies with long dorsal and anal fins.
- Most eels have no scales.
- The eel’s backbone is made up of over 100 vertebrae which makes it very flexible.
- Eels have gills and very sharp teeth.
- Eels live in both saltwater and freshwater.
- There are about 800 species.
- As marine animals and unlike reptiles, eels breathe underwater with their gills and fins, and therefore cannot survive outside of water.
- The European eel is normally around 60–80 cm (2.0–2.6 ft) and rarely reach more than 1 m (3 ft 3 in), but can reach a length of up to 1.5 m (4 ft 11 in) in exceptional cases.
- The European eel is a critically endangered species.
- Since the 1970s, the number of eels reaching Europe is thought to have declined by around 90% (possibly even 98%).
- Several projects have been started to prevent them from becoming endangered.
- In 1997, Innovatie Netwerk in the Netherlands initiated a project where they attempted to get European eels to breed in captivity
- While the species’ lifespan in the wild has not been determined, captive specimens have lived over 80 years. A specimen known as “the Brantevik Eel” lived for 155 years in the well of a family home in Brantevik, a fishing village in southern Sweden.
- The largest species, the slender giant moray eel, can grow to 13 feet in length.
- The electric eel is a South American freshwater fish found mainly in the Amazon River basin.
- The electric charge is produced by special organs along the sides of the eel’s body.
- The electric discharge from an electric eel can be stronger than 500 volts.
- The eel uses the electric charge against its predators and to catch its prey.
- The electric eel is a carnivorous hunter, meaning that it eats other animals. It’s a toothless fish and must swallow its food whole.
Life Cycle
- Much of the European eel’s life history was a mystery for centuries, as fishermen never caught anything they could identify as a young eel.
- Eels undergo considerable development from the early larval stage to the eventual adult stage, and most are predators.
- Unlike many other migrating fish, eels begin their life cycle in the ocean and spend most of their lives in fresh inland water, or brackish coastal water, returning to the ocean to spawn and then die.
- In the early 1900s, Danish researcher Johannes Schmidt identified the Sargasso Sea as the most likely spawning grounds for European eels.
- The larvae (leptocephali) undergo considerable development from the early larval stage to the eventual adult stage, and most are predators.
- They drift towards Europe in a 300-day migration.
- When approaching the European coast, the larvae metamorphose into a transparent larval stage called “glass eel”, enter estuaries, and many start migrating upstream.
- After entering their continental habitat, the glass eels metamorphose into elvers, miniature versions of the adult eels.
- As the eel grows, it becomes known as a “yellow eel” due to the brownish-yellow color of its sides and belly.
- After 5–20 years in fresh or brackish water, the eels become sexually mature, their eyes grow larger, their flanks become silver, and their bellies are white in color. In this stage, the eels are known as “silver eels”, and they begin their migration back to the Sargasso Sea to spawn.
- Silvering is important in an eel’s development because it allows for increased levels of the steroid hormone cortisol, which is needed for their migration from freshwater back to the sea.
- Cortisol plays a role in the long migration because it allows for the mobilization of energy during migration.
- Also playing a key role in silvering is the production of the steroid 11-Ketotestosterone (11-KT), which prepares the eel for structural changes to the skin to endure the migration from freshwater to saltwater.
- After the eel breeds, it dies.
- It takes a young eel three years to become an adult.
Habitat and Feeding
- Eels are found throughout the world.
- Eels 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.
- Most eels hide and live in caves and rock crevices.
- They also burrow in the sand.
- These behaviors allow them to surprise and attack their prey.
- Some eels will actually chase their prey and the rocks provide protection for the eel.
- Eels eat insects, fish, and crustaceans as part of their carnivorous diet.
- They also eat mollusks.
- They are carnivorous predators that eat a very diverse diet, including just about any marine creature that is smaller than them.
- Eels typically eat everything they can fit into their mouth. They won’t go for animals of the same size.
Human Uses for Eels
- Eels have been important sources of food both as adults (including jellied eels of East London) and as glass eels.
- Glass-eel fishing using basket traps has been of significant economic value in many river estuaries on the western seaboard of Europe.
- Eels’ blood is poisonous, which discourages other creatures from eating them.
- A very small amount of eel blood is enough to kill a person, so raw eel should never be eaten.
- Their blood contains a toxic protein that cramps muscles, including the most important one.
- As long as the eel is appropriately prepared and cooked all the way through, it is safe for eating.
- During the preparation process, the eel is filleted and drained of its blood, and then the heat from cooking kills the harmful toxins in the meat.
Eel Worksheets
This bundle contains 9 ready-to-use Eel Worksheets that are perfect for students who want to learn more about Eels which may look like a snakes, but they are actually fish. There are over 800 different species of eel. Freshwater eels are known to travel as far as 4,000 miles to breed.
Download includes the following worksheets:
- Eel Facts
- Parts of an Eel
- Eel Families
- Life of an Eel
- Enchelion Montium
- Eel Industry
- Lengthy Eel
- Eel Meal
- Word Building
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Link will appear as Eel Facts & Worksheets: https://kidskonnect.com - KidsKonnect, June 12, 2017
Use With Any Curriculum
These worksheets have been specifically designed for use with any international curriculum. You can use these worksheets as-is, or edit them using Google Slides to make them more specific to your own student ability levels and curriculum standards.