Biologists studying the eyes of hagfishes are revealing unexpected similarities to those found in other vertebrates, including humans.
A new study by biologists at the University of Alberta has revealed that the answer to the ancient puzzle of the evolutionary origins of vertebrate eyes may lie in hagfishes.
Lead author Emily Dong, who conducted the research during her graduate studies with Ted Allison, a professor at Hagfish Eye College, explained that it helps us understand the origins of human vision by expanding our understanding of the early steps in the evolution of vertebrate eyes. The sciences and a member of the Institute of Neurosciences and Mental Health U of A. “Our findings solidify the place of hagfishes among vertebrates and open the door for further research to uncover subtle details of their visual system.”
For years, hagfish eyes were thought to be different from those of vertebrates – so researchers were surprised to discover that hagfish eyes have many of the same features. These include neurons that connect photosensitive photoreceptors to ganglion cells, the continuous growth of the eye late into puberty, and a hidden layer of supportive cells that are prominent in other vertebrates and that are key to photoreceptor function.
“This is important because it broadens the picture of the early evolution of the vertebrate eye,” Dong explained. “The fossil record can only provide us with limited information, because soft tissues like eyes are not well preserved. So we are looking at living members of these early strains, like hagfishes.”
The hadfish is the oldest lineage of vertebrates still living today, representing vertebrates before the evolutionary emergence of jaws or double fins, such as limbs. As a result, the study of hagfishes provides important information about the early development of vertebrates, laying the foundation for what scientists can learn by studying other animal models such as zebrafish and mice.
“The data shed light on the confusing and dimly lit evolutionary origins of the vertebrate eye,” added Allison, a professor in the Department of Biological Sciences and supervisor of Master Dong.
Dong is now a PhD student at the University of Toronto. The research was funded by the Canadian Natural Sciences and Engineering Research Council and the Bamfield Center for Marine Science.
The study, “Characteristics of vertebrates revealed in the primitive eye of the Pacific hagfish (Eptatretus stoutii)” is published in Proceedings of the Royal Society b.