It is hard to believe that not so
long ago, such remains were so rare that biologists refused to believe in the
existence of such creatures except for the secondary evidence caused by scaring
on their chief predator, the sperm whale.
That is obviously no longer much of a problem.
We are reaching the point in
which we will have ubiquitous deep sea vessels able to provide a wind shield
like view and associated lighting. A
sonic gun can be also useful in killing specimens and allowing their recovery. The real problem is bringing such specimens
to surface without the tissue exploding.
I am expecting a fairly dramatic
era of deep sea discovery once that happens as a whole new world of species
from the deep is discovered. I expect to
see the famous sea serpent down there. In particular.
Giant Squid Killed by Sound?
"We now have proof" sonar blasts can harm squid, expert says.
Main Content
Workers recover the remains of a female giant squid in Spain 's Asturias
Photograph by Fernando Camino, Cover/Getty Images
Ker Than
Published May 3, 2011
When giant
squid were found dead off Spain about
a decade ago, scientists suspected that powerful sound pulses from ships had
harmed the animals. Now the evidence may be in.
A new study says low-frequency sounds from human activities can affect
squid and other cephalopods, not just whales and other marine mammals, which
have long been thought to be vulnerable to such pulses. (See "U.S.
Navy Sonar May Harm Killer Whales, Expert Says.")
The finding suggests noise pollution in the ocean is having a
much broader effect on marine life than previously thought, said study leader
Michel André, a marine bioacoustician at Barcelona's Technical University of Catalonia.
"We know that noise pollution in the oceans has a significant
impact on dolphins and whales [which use natural sonar to navigate and hunt].
... but this is the first study indicating a severe impact on invertebrates, an
extended group of marine species that are not known to rely on sound for
living," André said in a statement.
Giant Squid Mystery Solved?
In the early 2000s the remains of giant squid were found off Spain 's Asturias
province (map). In each case, the creatures' bodies appeared soon after
ships had used air guns to conduct low-frequency sound-pulse exercises in the
region, in some cases for oil-and-gas prospecting efforts.
Scientists investigating the giant squid remains at the time found
evidence of extensive bodily damage, including mantles reduced to pulp, bruised
muscles, and lesions in statocysts. These fluid-filled organs rest behind the
creatures' eyes and help giant squid maintain balance and position. (See pictures
of a colossal squid dissection.)
At the time, marine biologist Angel Guerra speculated—but was unable to
prove—that noise from prospecting ships was harming cephalopods and other
marine life.
"With this study, we now have proof" that low-frequency
sounds can harm cephalopods, said Guerra, a marine biologist at Spain's Marine Research Institute who was not
involved in the current study, which will appear in a future issue of the
journal Frontiers in Ecology
and the Environment.
Damage Worsened With Time
During the study, the research team examined the effects of
low-frequency sound exposure in 87 individual cephalopods belonging to four
species: two species of squid, one species of octopus, and one species of
cuttlefish. (See"Cuttlefish
Change Color, Shape-Shift to Elude Predators.")
For two hours the animals were exposed to sound with intensities of
between 157 and 175 decibels and frequency ranges of 50 to 400 Hertz.
These frequencies and intensities "are commonly found in the noise
produced by many activities at sea," such as military sonar tests or
efforts to detect oil and natural gas by gauging the nature of material beneath
the seabed, the Technical University of Catalonia's André told National
Geographic News.
After the sound exposure, the scientists killed the animals, either
immediately or up to 96 hours afterward.
The animals that were killed immediately after exposure showed signs of
damage to their statocyst tissue. Specifically, tiny hairlike structures in
statocyst cells—which bend as the cephalopods move through water and help the
animals balance—were lost, essentially crippling the creatures.
The animals allowed to live longer showed further damage, including
large, visible holes in the statocyst tissue.
"This is a typical process found in land mammals and birds after
acute noise exposure: a massive acoustic trauma followed by peripheral damage,
making the lesions worse over time," André said.
In their final seconds or hours, the test cephalopods "moved a
little bit, but they were not swimming, eating, or mating," André said.
A separate group of about a hundred cephalopods was not exposed to the
pulses. They remained healthy and behaved normally.
Both groups had been kept in the same aquariums before being separated,
and all the animals had behaved normally before the tests—ruling out the
possibility that the damage observed in the test group was due to captivity or
human handling, he said.
("Raise the Alarm" for Giant Squid?
Though the cephalopods in the experiments were much smaller than giant
squid, the experiments represent "the same phenomena as with the giant
squid," the Marine Research Institute's Guerra said.
The test animals are appropriate stand-ins for their giant squid
cousins, according to Guerra, who said he sees no reason why the findings
wouldn't apply to giant squid.
There are some differences in the damage, though.
The injuries to the giant squid found last decade, he noted, were much
more pronounced than in the experimental animals. Guerra attributes this to the
higher acoustic intensities and multiple sound sources giant squid are exposed
to in the real world.
And of course, the giant squid were found not just injured but dead,
unlike the test animals. But scientists say the case of the giant squid off Spain
At the time of the giant squid deaths, "we hypothesized that the
giant squid died in one of two ways: either by direct impact from the sound
waves or by having their statocysts practically destroyed and [the squid]
becoming disoriented," Guerra explained.
"The disoriented animals might wander up from the depths to the
surface, where the temperature difference kills them."
Marine zoologist Michael Vecchione, of the U.S.
Though the new research presents enough evidence to "raise the
alarm," more studies are necessary before a solid case can be made that
human-caused noise pollution is causing pervasive damage to marine life, said
Vecchione, who also did not participate in the study.
But, he added, "the evidence is accumulating that what [Guerra]
first proposed based on the giant squid might actually be correct."
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