Eel vs Lamprey: A Detailed Comparison

fish comparison aquatic animals eel vs lamprey marine life freshwater species ancient fish

Introduction

In the murky depths of our rivers and oceans, two serpentine swimmers are often mistaken for one another, yet they’re as different as sharks and dolphins. While eels and lampreys may share a similar body shape, they represent two vastly different evolutionary paths – one a true fish with a jaw-dropping life cycle, the other an ancient survivor that predates the dinosaurs.

Meet Our Animals

A sleek European eel glides sinuously above a sandy riverbed, its elongated body forming a graceful S-curve. The eel's smooth, dark greenish skin glistens underwater, fading to a lighter shade along its belly. Its streamlined head features small, forward-facing eyes and a broad, rounded snout. The continuous fin running along its body ripples subtly as it moves through the murky water. Small particles float in the dim, aquatic environment, creating a mysterious atmosphere typical of the eel's natural habitat.

A European eel demonstrates its characteristic sinuous swimming motion, showcasing the smooth, scaleless skin that helps it slip effortlessly through both fresh and salt water during its remarkable migrations.

A slender, eel-like sea lamprey swimming above a rocky riverbed. Its elongated, olive-brown body curves gracefully in an arc, displaying its smooth, scaleless skin. The distinctive circular mouth and characteristic row of small breathing holes along its side are visible. The lamprey's tubular body tapers slightly toward the tail, and its single eye is clearly visible on its streamlined head. The background shows a natural substrate of mixed colored pebbles and small rocks, creating a typical freshwater habitat setting. A second lamprey is partially visible resting on the rocky bottom below.

A sea lamprey displays its ancient lineage with its distinctive row of gill openings and specialized mouth structure – a reminder that these remarkable creatures have survived virtually unchanged for over 360 million years.

Key Differences at a Glance

Feature	Eel	Lamprey
Mouth Structure	Jawed mouth with small teeth	Circular suction disc with rasping teeth
Breathing	Internal gills with covers	7 external gill holes on each side
Skeleton	Bony	Cartilaginous
Size	Up to 1.5m (5ft)	30-90cm (1-3ft)
Diet	Predator (fish, crustaceans)	Parasitic or filter feeding
Age at Maturity	5-20 years	4-7 years

Eel: Special Features

True eels are masters of metamorphosis, undergoing one of nature’s most dramatic transformations. Starting life as transparent leaf-shaped larvae called leptocephali, they drift across entire oceans before transforming into glass eels. Their most remarkable feat? The ability to absorb up to 60% of their skeleton to prepare for their epic breeding migration to the Sargasso Sea, where depths reach 700 meters (2,300 feet).

Lamprey: Special Features

Lampreys are living fossils, maintaining their primitive features for over 360 million years. Their most distinctive feature is their oral disc – a remarkable piece of biological engineering that can exert suction forces of up to 11 kilopascals. Some species use this disc to rasp through the scales of fish and feed on their blood, while others use it to anchor themselves to rocks while filter feeding.

Fascinating Facts

While eels can swim backward with the same agility as forward, lampreys must always move forward due to their unique gill structure. Even more surprisingly, lampreys have a third eye! Known as the pineal eye, this light-sensitive organ sits atop their head, helping them maintain circadian rhythms and seasonal behaviors.

Conclusion

Though their serpentine forms might suggest similarity, eels and lampreys represent two fascinating but distinct approaches to aquatic life. While eels showcase the versatility of modern fish with their incredible metamorphosis and migration, lampreys offer us a window into our distant past, demonstrating how successful their ancient body plan has been through hundreds of millions of years of evolution.