Agnathans are jawless fish in the phylum Chordata, subphylum Vertebrata. Recent molecular data strongly supports the hypothesis that living agnathans are monophyletic.
The oldest fossil agnathans appeared in the Cambrian, and two groups still survive today: the lampreys and the hagfish.
Studies place hagfish and lampreys as being more closely related than either is to the jawed fishes.
Lampreys resemble eels and have smooth, slippery skin and a skeleton made completely of cartilage. They have seven pore-like gill openings on each side of the head.
Jawless Fish Facts for Kids
- You can find Lampreys in freshwater rivers and the ocean
- Lampreys begin as eggs and then larvae.
- Some species live up to around 8 years
- They feed by suction
- Some lampreys are parasites
Types of jawless fish
There are two types of jawless fish: hagfish and lampreys.
They feed on dead and dying fish. Find them in muddy bottoms, moderate depths, and cold waters around the tunnels they dig. About 20 hagfish species are known worldwide.
Freshwater lampreys can be found in temperate regions. The temperate zone lies between the tropics and the poles.
As adults, some migrate to the sea. Lampreys eat other fish.
Lampreys can attach to other fish and suck their blood. They also eat bottom invertebrates. There are about 30 lamprey species worldwide.
Jawless fish Characteristics
Lampreys and hagfish are jawless fish. Jawless fish lack jaws, fins, and stomachs. They have a notochord, paired gill pouches, a pineal eye, and a two-chambered heart.
What is unique about jawless fish?
The fish look primitive. It has a long, eel-like body and cartilage instead of bone. It doesn’t have a jawbone. Just a round, open mouth called an oral disc.
Are jawless fish dangerous?
There is no risk or danger to humans associated with them.