Body Shape
- Lampreys:
- Elongated, eel-like body
- Round or oval cross-section
- Hagfishes:
- Tube-shaped body
- Circular cross-section
Gill Structure
- Lampreys:
- Have seven pairs of round external gill openings on either side of their head
- Hagfishes:
- Have a single median gill opening on the underside of their head
Teeth
- Lampreys:
- Have rows of small, sharp teeth on their oral disc used for rasping and scraping flesh.
- Hagfishes:
- Have rows of small, conical teeth and horny toothplates on their tongue, used for scraping food.
Skeleton
- Lampreys:
- Have a cartilaginous skeleton, including a notochord and a cartilaginous cranium.
- Hagfishes:
- Have a mostly cartilaginous skeleton, with some calcified elements, but they lack a distinct backbone and vertebrae.
Reproduction
- Lampreys:
- Most species are anadromous, migrating between freshwater and saltwater to reproduce.
- Females lay eggs, and males fertilize them externally.
- Hagfishes:
- Are fully marine fish.
- Reproduce through internal fertilization, and females give birth to live young.
Habitat
- Lampreys:
- Some species are freshwater, while others are marine or anadromous.
- They are found in temperate regions around the world.
- Hagfishes:
- Are exclusively marine fish, found in deep waters, particularly around continental slopes and ocean basins.
Feeding Behavior
- Lampreys:
- Parasitic species attach to fish and feed on their blood and body fluids using a specialized oral disc.
- Some species are filter feeders.
- Hagfishes:
- Scavengers and predators, feeding on dead or dying fish and other marine animals.
- They have a unique "slime thread" that helps them capture and subdue prey.
In summary, lampreys and hagfishes are both jawless fish but differ in body shape, gill structure, teeth, skeleton, reproduction, habitat, and feeding behavior.