Anglerfish are bizarre-looking creatures, not least because of their lure. The rod-like structure that protrudes from the head of female anglerfish is so peculiar and distinctive that Aristotle gave them the nickname “fishing frogs.”
Now, researchers writing in the journal Ichthyology & Herpetology have described the evolutionary history of this strange feature, dating its origin to a common ancestor that existed around 72 million years ago in the Late Cretaceous, while highlighting the diversity that exists in anglerfish today.
“The really interesting thing is they’re found across the planet in different oceans and habitats. They’re in coral reefs, continental shelves, deep-sea habitats, floating on giant algae mats in the middle of the ocean,” lead author Alex Maile, a doctoral student with KU’s Biodiversity Institute and Natural History Museum at the University of Kansas, said in a press release. “All of them are doing this really cool thing using this lure in so many ways.”
The Anglerfish’s Lure
To date, there has been relatively little data on how anglerfish use their lures – “Many have never even been filmed or observed alive,” co-author Matthew Davis, a professor of biology at St. Cloud State University, said in a press release.
To rectify the situation, Maile and Davis examined 118 specimens representing 102 species stored in museum collections. Computer modeling enabled the researchers to make links between lure type and animal behavior and habitat, with deep-sea anglerfish sporting bioluminescent lures displaying different strategies than those that live closer to shore.
Explore All OptionsMaile and Davis conclude lures serve two purposes: to catch prey and attract mates.
Mechanical Lures to Bioluminescent Lures
According to the study, the original lure would have been mechanical, and it would have emerged around 72 million years ago. It was only as anglerfish moved to the pelagic zone, where there is minimal sunlight, that some began to develop the glow typical of many deep-sea fish.
Ceratias tentaculatus, anglerfish species.
(Image Credit: Alex Maile)
This occurred between 34 million and 23 million years ago, during the Oligocene period, and coincided with a sudden proliferation of species, as well as a longer lure that extended further away from the body. According to Maile, this is a pattern also observed in many other deep-sea groups, such as lanternfishes and dragonfishes, which also use light to communicate with other members of their species.
In a statement, Maile said, “There have been hypotheses that they’re using the lure to communicate with males. The males have really big noses and relatively big eyes. The lure has adaptations like a little window shutter. They can contract muscle fibers around it and modulate the light in patterns.”
While the lure appears to play a role in mate attraction, “It remains unclear whether the elaboration of female lures initiated the evolution of male sensory specialization, or if male detection ability selected for more conspicuous female lures,” the researchers wrote in the study.
Evolution of Chemical Lures
Some anglerfish have taken the lure a step further, evolving an appendage that can secrete chemicals that attract prey. This has occurred twice in two separate groups.
First, a group called batfishes developed a chemical lure 49 million years ago during the Eocene. The lure helps the batfish attract and ensnare its prey. According to Maile, they can be moved like a slide whistle, shooting out of the upper skull and secreting chemicals.
Second, a species of frogfishes, which developed its chemical lure comparatively recently, 5 million years ago. They also use it to entrap prey, which is attracted to the chemicals.
While the study offers “a preliminary framework” into the lure and its evolutionary history, Maile and Davis point out the lack of data available when it comes to this strange and mysterious group of fish.
“Together, these findings demonstrate that lure morphology and function are intricately linked to habitat and behavior, supporting the hypothesis that they have played a key role in the evolutionary history and diversification of the Lophioidei,” they wrote in the study.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Ichthyology & Herpetology: The Evolution of Lures in Anglerfishes (Acanthuriformes: Lophioidei): Investigating Nature's Tackle Box
