Lampreys are ancient, eel-like aquatic creatures that have navigated Earth’s waters for millions of years. These unique fish often spark curiosity due to their distinctive appearance and habits. A common question arises when observing them: do lampreys possess jaws?
The Jawless Reality
Lampreys do not have jaws, a feature that distinguishes them from most fish and other vertebrates. Their mouth is a specialized, round, sucking disc lined with numerous rows of horny, keratinized teeth. This oral disc allows them to attach firmly to surfaces or other organisms.
Unlike the hinged jaws of most fish, which enable biting and chewing, a lamprey’s mouth opens as a fixed, suction-cup-like aperture. This difference classifies them as “agnathans,” a superclass of jawless fish that also includes hagfish.
Lampreys possess a piston-like tongue equipped with three horny plates, one positioned transversely and two longitudinally. This tongue is highly mobile and functions as a rasping tool. The oral disc teeth help the lamprey maintain attachment. An internal ring of cartilage supports the rim of the mouth.
A Unique Feeding Mechanism
Without the ability to bite or chew, lampreys employ a distinct feeding strategy. Many species are parasitic as adults, attaching to host fish using their oral disc. Once attached, their rasping tongue bores through the host’s scales and skin, creating a wound. This allows the lamprey to feed on the host’s blood and body fluids.
Parasitic lampreys secrete an anticoagulant enzyme that prevents the host’s blood from clotting. While some lamprey species are parasitic, others are non-parasitic and do not feed as adults, relying on larval energy reserves. These non-parasitic species use their oral disc and tooth plates for clinging to surfaces. Their hydraulic system enables suction for attachment.
Evolutionary Insight
The jawless nature of lampreys provides insight into early vertebrate evolution. Lampreys are among the oldest surviving vertebrate lineages, with ancestors appearing around 518 million years ago. They represent a stage in vertebrate development that predates the evolution of jaws, a major turning point in life’s diversification.
The development of jaws enabled diverse feeding strategies and new food sources, leading to the rapid evolution of jawed vertebrates, or gnathostomes. Lampreys and hagfish are the only living agnathan groups, offering insights into the common ancestor of all vertebrates.
Their cartilaginous skeleton is a primitive trait shared with early vertebrates. Studying lampreys helps researchers understand how biological processes and anatomical features, such as the nervous system and stem cell networks, evolved before jaws.