Vampires🧛, the mythical creatures roaming in darkness sucking blood, are horrifying yet so popular in books, movies and video games. You may think they are monsters that only exist in people's fantasies, but many species, called hematophagous, actually rely on the blood🩸 of other species for their own survival. Today, we’ll introduce one of those coming from the darkness of the ocean, the "vampire fish" 😧!
With their disc-shaped head, and their large truncated mouth, lampreys are more funny-looking than terrifying when looked from aside. But in full face view, their mouth ringed by multiple rows of terrifying razor-sharp horn-shaped teeth🦷, lampreys appear coming straight from the imagination of a sci-fi writer. Yet, lampreys are vertebrates belonging to the Petromyzontiformes order and currently around 40 species globally have been described. Many of them, such as the sea lamprey (𝘗𝘦𝘵𝘳𝘰𝘮𝘺𝘻𝘰𝘯 𝘮𝘢𝘳𝘪𝘯𝘶𝘴), are hematophagous🩸. With their suction-cup-like mouth, these parasitic fish attach to their hosts, rasping away the fishes' scales with the rough tongue and digging their sharp teeth into the flesh. They then secrete lamphredin, an enzyme which prevents blood from clotting, and slurp the lives out of the victims☠️! And if in most cases, their damages remain limited, under particular conditions it can become quite serious.
This is what happened in the 1930s, when these "vampires" caused a great collapse in the fisheries of the Great Lakes as an invasive species. In the sea lamprey's native Atlantic Ocean, their hosts have co-evolved with the parasite and typically wouldn't be killed by the hematophagy. However, after the sea lamprey was accidentally introduced to the Great Lakes, many native host fishes were not able to survive their parasitism, either dying directly or indirectly by infections on the wound caused. Over their feeding period, each lamprey was able to kill more than 20 kg of fishes🐟! Fortunately, the native fish populations were allowed to recover after effective control methods such as the implementation of lampricide and barriers. Another example of problems caused when a species is being introduced into a region outside of its native range.
However, don't think of lampreys as despicable monsters that do no good to others. Actually, they are amazing ‘living fossils’🦴 which survived 4 major extinction events, and have remarkably remain similar morphologically for the past 360 million years, as shown from fossil records. Although sometimes called "lamprey eels", lampreys are distinctively different from eels, as they are not bony fishes. They are jawless and have a cartilaginous skeleton--they have a series of cartilaginous structures, called the arcualia, arranged above the notochord, instead of a true vertebra. Together with the hagfish (order Myxiniformes), lampreys are the only extant representatives of the jawless vertebrates, the Agnathans. They are thus considered as one of the most primitive animals of all vertebrate species, and occupy a key🔑 phylogenetic position in providing insights to the origins and evolutionary history of modern vertebrates, allowing scientists to explore the embryology, genomics, and body plan of our ancestral vertebrates.
Are you interested to see the specimen of this unique jawless fish? Do you wanna confirm how they are different from other fishes with your own eyes? Grab your chance to visit the Hong Kong Biodiversity Museum and come appreciate these amazing animals!
Text: Winnie Lam
Comentários