In the midwater, the need to see without being seen in this dim, open environment, has led to extraordinary visual adaptations. Many midwater animals have evolved powerful eyes that allow them to detect prey, mates, and predators in the dark. New research by scientists at The University of Western Australia’s Oceans Institute and the Smithsonian’s National Museum of Natural History—including MBARI Adjunct Karen Osborn—explores the unique visual system of hyperiid amphipods, shrimp-like crustaceans that live in the ocean’s twilight zone.

Hyperiid amphipods have evolved remarkably diverse eyes, each with different functional capabilities. Scientists have only discovered about 340 species of hyperiid amphipods, but the diversity of their eyes rivals that seen among the millions of species of terrestrial insects.

Using 3D imaging and computational modeling, the research team compared the structure and function of the eyes of three different deep-sea hyperiids.

Hyperia has evolved eyes that keep watch on a wide field of view, but can only visualize objects nearby. Phronima—commonly known as the barrel amphipod—and Streetsia can see well into the distance, but at the cost of a narrow field of view. Phronima has solved this problem by evolving a second pair of eyes for an expanded, but poor, visual field. Streetsia sees really well in a narrow ring surrounding their body that they use to continuously scan the surrounding water as they swim.

While hyperiid amphipods live in a relatively simple environment—a wide expanse of open water—their individual behaviors and the need for transparent camouflage have driven the diverse eye structures among species in this group.

Understanding the eye structures of these midwater amphipods may one day help us develop new technologies for seeing in dark environments like caves, outer space, and the deep sea.

Jessop, A-L., Z.M. Bagheri, J.C. Partridge, K.J. Osborn, and J.M. Hemmi. 2024. Functional differences between the extraordinary eyes of deep-sea hyperiid amphipods. Proceedings of the Royal Society B, 291: 20240239. https://doi.org/10.1098/rspb.2024.0239

Learn more about the barrel amphipod: https://www.mbari.org/animal/barrel-a...

Producer/editor: Kyra Schlining
Science advisor: Karen Osborn
Production team: Raúl Nava, Susan von Thun
Music: Secret Inquiries by Taras Shostukha (Motion Array)

Animals in order of appearance:
0:00 Hyperia sp. (hitchhiker amphipod) hitchhiking on Calycopsis simulans (midwater jelly) | 364 meters (1,194 feet) | Monterey Canyon
0:09 Hyperia sp. (hitchhiker amphipod) hitchhiking on Aegina sp. (golf tee jelly) | 434 meters (1,424 feet) | Soquel Canyon
0:13 Hyperia sp. (hitchhiker amphipod) hitchhiking on Solmissus sp. (dinner plate jelly) | 1,193 meters (3,914 feet) | Monterey Canyon
0:18 Phronima sedentaria (barrel amphipod) brooding eggs inside a salp | 219 meters (719 feet) | Monterey Canyon
0:27 Phronima sedentaria (barrel amphipod) brooding eggs inside a salp | 337 meters (1,106 feet) | Monterey Canyon
0:37 Free-swimming Phronima sedentaria (barrel amphipod) | 458 meters (1,503 feet) | Monterey Canyon
0:46 Free-swimming Phronima sedentaria (barrel amphipod) | 228 meters (748 feet) | Monterey Canyon
0:57 Streetsia sp. (sharp-nosed amphipod) swimming past a green caterpillar siphonophore (Lilyopsis fluoracantha) | 318 meters (1,043 feet) | Monterey Canyon