Squid recorded color-matching substrate for the first time
Date:
April 5, 2022
Source:
Okinawa Institute of Science and Technology (OIST) Graduate
University
Summary:
A new study has found that squid will camouflage against coral
reef and other substrate as a way of avoiding predation.
FULL STORY ========================================================================== While octopus and cuttlefish are famous for their use of camouflage
to match the color of the substrate, a third type of cephalopod --
the squid -- has never been reported displaying this ability. Now, in
a study published in Scientific Reports, scientists from the Physics
and Biology Unit at the Okinawa Institute of Science and Technology
Graduate University (OIST) have shown that squid can and will camouflage
to match a substrate as a way of avoiding predators. This work opens
up research avenues on how squid see and perceive the world around
them. Furthermore, it sheds light on their behavior, and thus could go
on to inform conservation initiatives.
========================================================================== "Squid usually hover in the open ocean but we wanted to find out what
happens when they move a bit closer to a coral reef or if they're chased
by a predator to the ocean floor," explained one of the three first
authors, Dr. Ryuta Nakajima, OIST visiting researcher. "If substrate
is important for squid to avoid predation than that indicates that
increases or decreases in squid populations are even more tied to the
health of coral reef than we thought." Previous studies on cephalopod camouflage have mostly been conducted on cuttlefish and octopus. Squid,
as an animal that tends to live in the open ocean, are notoriously hard
to keep in captivity and so have been rather avoided for this kind of
research. But, since 2017, the scientists in the OIST's Physics and
Biology Unit have been culturing a species of oval squid in captivity.
This squid, locally known as Shiro-ika, is one of three oval squids found
in Okinawa. When in the open ocean, they are light in color, meaning that
they blend into the ocean surface and flickering sunlight above. But the researchers suspected that when they moved closer to the ocean floor,
it would be a different story entirely.
At OIST's Marine Science Station, the oval squid were, almost
accidentally, observed camouflaging to the substrate for the first
time. The researchers were cleaning their tank to remove the algal
growth. They noticed that the animals were changing color depending on
whether they were over the cleaned surface or the algae.
Following this observation, the researchers performed a controlled
experiment.
They kept several squid in a tank and cleaned half of the tank, leaving
the other half covered in algae. They placed an underwater camera inside
the water and suspended a regular camera above, so they could capture
and run statistical tests on any color changes.
The results were clear. When the squid were in the clean side of the
tank, they were the light color. But when they were above the algae,
they promptly became darker.
The experiment uncovered an ability that had never previously been
reported in squid. The researchers highlighted that as well as opening
up exciting avenues for exploring the visual capabilities of the animal,
the study also showed that substrate is clearly useful for these squid
to survive.
"This effect really is striking. I am still surprised that nobody has
noticed this ability before us," said another first author, Dr. Zdenek
Lajbner. "It shows just how little we know about these wonderful animals."
Dr. Nakajima stated that this particular squid is important for Okinawa
for economic and cultural reasons. "It was actually the local fishermen
who were the first ones distinguishing three species of oval squids in
Okinawa, long before the scientists," said Dr. Nakajima.
"We look forward to continuing to explore the camouflage capabilities of
this species and cephalopods more generally," said Prof. Jonathan Miller, Principal Investigator of OIST's Physics and Biology Unit and the senior
author of the research article.
========================================================================== Story Source: Materials provided by Okinawa_Institute_of_Science_and_Technology_(OIST)
Graduate_University. Original written by Lucy Dickie. Note: Content may
be edited for style and length.
========================================================================== Related Multimedia:
* Oval_squid_images_and_video ========================================================================== Journal Reference:
1. Ryuta Nakajima, Zdeněk Lajbner, Michael J. Kuba, Tamar Gutnick,
Teresa L. Iglesias, Keishu Asada, Takahiro Nishibayashi, Jonathan
Miller.
Squid adjust their body color according to substrate. Scientific
Reports, 2022; 12 (1) DOI: 10.1038/s41598-022-09209-6 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220405084559.htm
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