WHOI’s new In-situ Ichthyoplankton Imaging System (ISIIS) captures incredibly detailed images of tiny animals called zooplankton, plant-like phytoplankton, jellies, and small fish. The system takes 14 shadowgraph images of organisms that pass through it each second, producing a huge amount of data on the natural behavior of miniscule creatures in the twilight zone. ISIIS is towed behind a ship on a small, commercially-available Stingray “sled,” which also holds sensors that measure depth, oxygen, salinity, temperature, and other water characteristics.

Data collected by ISIIS will be essential for understanding how plankton fit into the ecosystems of the twilight zone and the ocean as a whole. These microscopic organisms form the base of many ocean food webs, play a key role in producing oxygen, and in some cases, remove carbon dioxide from the atmosphere, helping to regulate Earth’s climate. In spite of their importance, however, marine plankton communities are not well understood—in part because the ocean is vast, and plankton communities vary widely by location and over time.


DimensionsLength: 7.5 feet (2.28 meters)
Width: 4 feet (1.22 meters)
Weight500 lbs (2.26 kg)
Power300 volts (~45 watts)
Depth capability3,280 feet (1,000 meters)
EnduranceVaries by duration of ship transit
CommunicationsFiber optic cable
SensorsCTD (conductivity, temperature, depth) sensor; flurometer, optical backstcattering meter, PAR (phytosynthetically active radiation) meter; oxygen meterl; ADV (acoustic doppler velocimeter), ISIIS imaging system
Recovering the Stingray sled with ISIIS zooplankton imaging system. Heidi Sosik and Peter Weibe from Woods Hole Oceanographic Institution handle tag lines aboard R/V Endeavor on the Northeast U.S. Shelf Long-Term Ecological Research Winter Transect cruise. Photo by Ken Kostel, Woods Hole Oceanographic Institution.