Researchers Find Deep-Sea Squid With Tentacle Tips That “Swim” on Their Own
MOSS LANDING, Calif – A new discovery shows that deep sea squid are slower swimmers with a weak, gelatinous body as compared to it’s brothers, but the Grimalditeuthis bonplandi has adapted its tentacles to become a fierce predator.
Until just a few years ago, marine biologists could only work with dead or dying specines of G. bonplandi that had been captured in deep-sea trawl nets. However, recent developments have allowed scientists to use video from underwater robots known as remotely operated vehicles (ROVs), to study how these squids behave in their native habitat roughly one mile below the ocean surface.
The deep-sea squid Grimalditeuthis bonplandi seems to use a very different feeding strategy. A slow swimmer with a weak, gelatinous body, its tentacles are long, thin, fragile, and too weak to capture prey. Unlike any other known squid, its tentacles do not have any suckers, hooks, or photophores (glowing spots).
The lead author of the paper, Henk-Jan Hoving, was a postdoctoral fellow at MBARI from August 2010 until July 2013. He and his coauthors examined video of G. bonplandi taken during an MBARI ROV dive in Monterey Bay. They also analyzed video collected by several oil-industry ROVs in the Gulf of Mexico, as part of the Scientific and Environmental ROV Partnership Using Existing Industrial Technology (SERPENT) project. In addition, the researchers dissected over two dozen preserved squids from various collections.
When the ROVs first approached, most of the squids were hanging motionless in the water with their eight arms spread wide and their two long, thin tentacles dangling below. What intrigued the researchers was that the squids’ tentacles did not move on their own, but were propelled by fluttering and flapping motions of thin, fin-like membranes on the clubs. The clubs appeared to swim on their own, with the tentacles trailing behind.
Instead of using its muscles to extend its tentacles, like most squids, G. bonplandi sends its clubs swimming away from its body, dragging the tentacles behind them. After the tentacles are extended, the clubs continue to wiggle independently of the tentacles.
When threatened, instead of retracting its tentacles as most squids would do, G. bonplandi swims down toward its clubs. After swimming alongside its clubs, the squid coils both the tentacles and clubs and hides them within its arms before swimming away.
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