For more than a decade, researchers have been tagging large marine mammals such as dolphins and whales to reveal their behavior. But tagging small, soft animals such as jellyfish and squid has posed a big, hard challenge.
WHOI biologist Aran Mooney and collaborators at Stanford University and the University of Michigan have developed a new kind of data-logging tag, specifically designed for small and delicate invertebrates. The ITAG (the “I” stands for “invertebrate”) is small—1 by 4.25 by 2.5 inches. It has a hydrodynamic shape to minimize its impact on the animals and attaches to jellyfish with suction cups and a veterinary-grade tissue adhesive. For squid, researchers stitch it onto the animals’ backs using biodegradable sutures.
Squid and jellyfish play crucial roles in marine food webs, and squid is a vital commercial fishery. Yet little is known about their natural behaviors or physiology. As climate change warms the ocean and changes its chemistry, it is becoming increasingly important to understand how these animals will be affected, Mooney said.
Sensitive sensors on the ITAG can record animals’ swimming patterns and breathing rates, along with environmental conditions such as light and seawater temperature. The tags eventually detach from the animals’ bodies, float to the surface, and transmit data via a radio antenna back to computers in scientists’ labs.
“We wanted a tag that would be able to tell us what the animals are doing at different depths,” Mooney said. “When squid go down to a couple hundred meters, are they foraging at night or are they resting and getting away from top predators? Are they hovering or swimming faster or slower? What are their respiration rates?”
So far, the ITAG has been successfully tested on squid and jellyfish in the lab. The next step for the research team will be to try it out on free-swimming animals in the ocean.
This research was published September 2015 in Animal Biotelemetry. The research was supported by the WHOI Ocean Life Institute, the Innovative Technology Program, Stanford University’s Hopkins Marine Station’s Marine Life Observatory, and the National Science Foundation’s Ocean Acidification Program.