Sea Light: Exploring Light in Marine Habitats and the Eyes that Evolved to See ItLatest update January 3, 2019 Started on October 26, 2018
Evolution and biodiversity in the sea is driven in great part by light and vision. We study the weird and wonderful visual systems of diverse marine invertebrates including mantis shrimp and fan worms in order to discover how eyes and visual behaviours evolve beneath the waves. This project will facilitate the observation of natural visual behaviours as well as the measurement of the dynamic light environments these creatures reside in.
The Trident OpenROV has arrived! We are looking forward to getting it into the field later this month at Helford Passage Beach in Cornwall. We will be surveying the tidal sand flats where we find two fan worm species that we are working with: Acromegalomma vesiculosum and Sabella pavonina. Acromegalomma vesiculosum has large compound eyes on its feeding tentacles while Sabella pavonina has no eyes on the tentacles. We are curious to see how the tow different species respond to the encroaching ROV.
We study the visual systems of marine animals around the world; in field sites that include the Great Barrier Reef, Hawaii, the Caribbean, the Mediterranean Sea and the temperate North Atlantic. Vision is a crucial sense, governing complex behaviours such as navigation, communication, and predation. Vision is therefore likely a major contributor to speciation and biodiversity. Our primary focus is to discover how the dynamic aquatic light environment shapes the evolution of eyes and the behaviours they facilitate. Understanding how animals see is increasingly important when we consider how animals will meet the new challenges brought on by shifting light environments in a changing world.
Beyond our usual approaches of laboratory experimentation, we are increasingly interested in observing and testing the visual systems of marine creatures in their natural habitats. We have projects underway on diverse marine life with unusual eyes including mantis shrimp, planktonic crustaceans, jellyfish, and starfish. We plan to use an ROV in observing the behaviours of many of these animals in the future in their tropical natural habitats. However, the target of the first expedition will be closer to home: We will examine the unique visual behaviours of fan worms living in the Helford Estuary in Cornwall, UK.
Fan worms are marine polychaetes that spend their lives hidden in a tubes buried in the substrate. They project a fan of specialised tentacles up into the water column to filter feed, snatching food particles from the passing currents. Since their heads never leave their tubes, they have evolved dozens or hundreds of unique eyes scattered on their feeding tentacles. These eyes can warn the worms of encroaching threats so they can retract their feeding fans to safety. These are some of the strangest eyes in nature, and evolved independently from any other visual system.
We will use a ROV as an experimental stimulus to test the ability of fan worms in the shallow mud flats at the Helford feild site to detect the ROV and retract as it approaches in varying lighting conditions (approach direction, time of day, and depth). We will also use video recorded by the ROV to quantify the light properties (intensity, colour, rate/intensity of wave flicker) of various habitats and depth ranges in the estuary. This data will be bolstered by other specialised light measuring equipment deployed independently, or retrofitted to the ROV.
Stay tuned to see us spook some fan worms if we are successful in our application for a Trident ROV!
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