Difference between Hagfish and Lamprey

Hagfish and lampreys are jawless fishes (Agnathans) that are closely related to jawed vertebrates (gnathostomes). They are regarded as the examples of primitive vertebrates. These two fishes are the sole survivor and representative of the jawless fishes. Let us differentiate between the two jawless fishes, in the table below.

Hagfish, also known as slime eel or slime hags are characterised by the amount of slimes they produce. They are marine vertebrates (primitive) that belong to the superclass of Agnatha (the Agnathans are a superclass or subphylum of jawless fishes).

The classification of a hagfish is as follows:

Kingdom: Animalia

Phylum: Chordata

Superclass: Agnatha

Class: Myxini

Order: Myxiniformes

Family: Myxinidae

Known species of the eel include Eptatretus goliath, Myxine kuoi, and Myxine glutinosa.

Physically, hagfishes look like an eel, with scaleless bodies. They are soft skinned and have three pairs of barbels (whisker-like sensory organs projecting near the mouth). They can grow up to 40 inches long, and do not contain jaws or bones. They are cartilaginous, with a notochord running through their body. Their notochord does not develop into a vertebral column like a true vertebrate.

Though many animals secrete slime, hagfishes have multiple slime glands, and hence can produce up to 5 gallons of slime. The hagfishes act as nocturnal predators on small invertebrates, however they are better known for their scavenging abilities by consuming dead fishes. They can sometimes also eat the carcasses from inside out.

Hagfishes can be found in temperate and cold temperate regions worldwide, in ocean floors that are more than 30m deep. They are common in the diets of sea lions and seals. Commercially, their skin is used in the making of purses, wallets and briefcases.

The hagfishes produce slime as a response to stress. However, producing so much slime can sometimes be lethal for their own ventilation. To avoid drowning in their slime they form a knot in their tail that passes on to their head until the slime is wiped off. Additionally, the mucus helps in getting rid from the grip of predators.

Lamprey is a jawless fish-like vertebrate placed in the superclass Agnatha. Rather than having true vertebrae, it shows arcualia over the notochord.

Their classification is as follows:

Kingdom: Animalia

Phylum: Chordata

Superclass: Agnatha

Class: Hyperoartia

Order: Petromyzontiformes

Family: Petromyzontidae

Well-known genera of lampreys include Ichthyomyzon, Petromyzon, Lampetra and Lethenteron.

They are found in temperate regions worldwide except in coastal and fresh waters in Africa. They look like eels and have a scaleless body. They can grow up to 40 inches long. They are cartilaginous, without any bones or jaws present in their body.

Lampreys undergo metamorphosis where they develop from a burrowing freshwater larvae to parasitic adults. The lampreys begin their life after hatching from the eggs and forming a larvae called ammocoetes. They live in burrows in silt or mud in freshwater, and feed on microorganisms. At this stage they have underdeveloped eyes.

The larva then undergoes metamorphosis to migrate to the sea (the phenomenon of fish migration from fresh water to sea is called anadromy). They live a parasitic life in the sea where they attach themselves to a fish for nutritional requirements.

The lampreys however return to freshwater for reproduction. They build their nest, spawn (the process of laying eggs) and then die. However, some lampreys are non-parasitic, and do not migrate to the sea. They live in freshwaters for their whole life, reproduce and die. Example: Petromyzon marinus.

Hagfish

Lamprey

Description

Hagfish are slime producing eels that live in marine environments.

Lampreys are eels that are found both in freshwater as well as marine environments.

Alternate Name

Slime eel

No such alternate name.

Occurrence

It is found in marine environments.

It is found in both freshwater and seawater.

Parasitism

Hagfishes are parasitic in nature.

Some lampreys are parasitic while some are not.

Scavengers

Hagfishes feed on dead fishes.

No such practice is found in lampreys.

Slime Producing Capability

Hagfish produce a lot of slime, and it is a characteristic of the organism.

Lamprey does not produce slime.

Development

The development of hagfish is direct.

Lampreys undergo metamorphosis where they develop from a larva to an adult.

Known Genera

  • Eptatretus
  • Myxine
  • Ichthyomyzon
  • Petromyzon
  • Lampetra
  • Lethenteron

Importance

  • Hagfishes are common in the diet of sea lions and seals.
  • Their skins are used to make wallets, purses and briefcases.

No such importance was reported.

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Frequently Asked Questions on Difference between Hagfish and Lamprey

What is unique about lampreys & hagfish?

Lampreys and hagfish are unique jawless fishes that are the only representative of a once diversely found group of jawless fishes.

How are hagfish and lampreys different from all other vertebrates?

Hagfish and lampreys are primitive vertebrates that have a notochord running in their body. The notochord does not develop into a vertebral column as in true vertebrates.

Why are lampreys sometimes called vertebrates?

The adult lampreys have a cartilaginous vertebral element that is quite similar to vertebrates. This is the reason they are sometimes called vertebrates.

How do lampreys differ from other vertebrates?

The lampreys differ from other vertebrates in that they do not have jaws and bones.

Why did gnathostomes replace agnathans?

The gnathostomes (jawed fishes) took over the agnathans because of the evolution of jaws and paired fins. This gave the evolved organisms more mobility and a better predatory life.

How is a hagfish different from a true fish?

Hagfishes don’t have true fins. Instead of jaws, they have structures that move horizontally with keratinous teeth to tear off the food.

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