The key difference between hagfish and lamprey is that hagfish is not considered as a vertebrate while lamprey is a vertebrate.
Hagfish and lamprey are two groups of jawless, elongate eel-like animals lacking paired fins. These two groups are the only living representatives of ancient creatures that gave rise to fish and humans. Both fish do not have scales or paired fins. Moreover, they are boneless. Their skeletons are made of cartilages. All hagfish and most lampreys are marine. Lamprey has vertebra while hagfish lacks vertebra. Hence, lamprey is a primitive vertebrate, while hagfish is not considered as a vertebrate.
CONTENTS
1. Overview and Key Difference
2. What is Hagfish
3. What is Lamprey
4. Similarities Between Hagfish and Lamprey
5. Side by Side Comparison – Hagfish vs Lamprey in Tabular Form
6. Summary
What is Hagfish?
Hagfish is an eel-shaped slime-producing fish that lives exclusively in marine water. Hagfish is long, slender and pinkish. It is a jawless fish which has a poorly developed skull made form cartilage. Hagfish is boneless and do not have vertebra. Hence, it is not considered as a vertebrate. Its skeleton is cartilaginous. Hagfish belongs to class Myxini; a sister group of jawed vertebrates. They actually belong to superclass; Agnatha. Hagfish is closely related to lamprey. There are about 35 species of hagfish.
Figure 01: Hagfish
Hagfish are deep-sea scavengers. They are capable of generating a massive amount of slime. For this reason, hagfish are sometimes called “slime eels” though they are not eels. Slime production is an anti-predatory mechanism of hagfish. Slime gives a slippery exit and helps them to defend themselves against predatory attacks by fishes. Moreover, hagfish have four pairs of thin sensory tentacles surrounding their mouths to catch food. They also can absorb nutrients directly through their skin. Furthermore, they are almost blind.
What is Lamprey?
Lampreys are jawless fish-like animals. They are closely related to hagfish. However, Lamprey has vertebra and a well-developed skull. Hence, they are true vertebrates, unlike hagfish. Lamprey lacks scales and paired fins similar to hagfish. Moreover, they are eel-like fish.
Figure 02: Lamprey
There are about 41 species of Lamprey. Lamprey species can be parasitic or non-parasitic. They live in freshwater as well as in marine water. Lamprey body is less slimy. They do have a functional pair of eyes. Their mouth is ventral. Skeleton of lamprey is made from cartilages. Hence, they lack bones.
What are the Similarities Between Hagfish and Lamprey?
- Hagfish and lamprey are jawless, elongate eel-like animals.
- They belong to superclass Agnatha.
- They do not have paired fins.
- Moreover, they have no scales.
- Both belong to phylum Chordata.
- They have unmyelinated axons.
- Their skeletons are made of cartilage.
What is the Difference Between Hagfish and Lamprey?
Hagfish is an eel-like slime producing marine jawless fish while lamprey is an eel-like jawless fish that lives in coastal and freshwaters. Hagfish does not possess vertebra while lamprey has vertebra. Hence, hagfish is not considered as a vertebrate while lamprey is a vertebrate. So, this is the key difference between hagfish and lamprey.
The below info-graphic tabulates side by side more differences between hagfish and lamprey.
Summary – Hagfish vs Lamprey
Hagfish and lamprey are two groups of jawless fish which are eel-like. Both lack scales and paired fins. Moreover, they are boneless fish. The key difference between hagfish and lamprey is that hagfish does not have vertebra while lamprey has vertebra. Therefore, hagfish is not considered as a vertebrate while lamprey is a vertebrate.
Reference:
1. “Introduction to the Myxini” University of California Museum, Available here.
2. “Lamprey.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
Image Courtesy:
1. “Six gill hagfish Eptatretus hexatrema at the Oakburn DSC09112” By Peter Southwood – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Jõesilmud2” By Tiit Hunt – Own work (CC BY-SA 3.0) via Commons Wikimedia