Petromyzon
Petromyzon is a genus of lampreys, jawless fish that are parasitic on other fish. They are found in both marine and freshwater environments, and are characterized by their eel-like bodies, circular mouths with rows of teeth, and a lack of paired fins. The genus Petromyzon is the type genus of the family Petromyzontidae, which includes all lampreys.
Common Names
Members of the genus Petromyzon are commonly known as sea lampreys, although they are not all strictly marine. Other common names include lamprey, lamper eel, and river lamprey. The specific epithet of the type species, Petromyzon marinus, is Latin for "sea-worm".
Characteristics
Like other lampreys, members of the genus Petromyzon have several distinctive characteristics:
- Eel-like body: They have a long, slender, cylindrical body with a single, continuous dorsal fin.
- Circular mouth: Their mouth is circular and surrounded by a ring of teeth. They use their teeth to attach to their prey and rasp away flesh and blood.
- Lack of paired fins: They lack paired fins, which are found on most fish.
- Notochord: They have a notochord, which is a flexible rod that runs along their back and serves as a support structure.
- Seven gill openings: They have seven gill openings on each side of their head.
Environments
Members of the genus Petromyzon are found in both marine and freshwater environments. Some species are anadromous, meaning they spend part of their life cycle in the ocean and part in freshwater. Others are strictly freshwater.