SECTION 4: LATERAL SENSE ORGANS AND CONVERGENT EVOLUTION
Squids have Lateral sense organs (to keep aware of others near them) and they use schooling behaviour in a similar manner to fish with which they compete.
Andrew Packard in the paper ‘Cephalopods and fish: the limits of convergence’ presents evidence for considering the convergence as due not merely to similar physical demands of the marine environment, but to dynamic interactions between cephalopods and vertebrates since the late Palaeozoic. The convergence was set on its way when the two groups, independently of each other, acquired locomotory methods that allowed them to increase in size. The loss of the chambered shell was an evolutionary response to the needs of increased mobility and to the need to go deeper as vertebrate predators pushed out into oceanic waters.
In their paper A lateral line analogue in cephalopods: water waves generate micro phonic potentials in the epidermal head lines of Sepia and Lolliguncula, authors, Bernd U. Budelmann and Horst Bleckmann, write that epidermal lines on their heads and arms are an analogue to the lateral lines of fish and aquatic amphibians and thus are another example of convergent evolution between a sophisticated cephalopod and vertebrate sensory system.
Squids have Lateral sense organs (to keep aware of others near them) and they use schooling behaviour in a similar manner to fish with which they compete.
Andrew Packard in the paper ‘Cephalopods and fish: the limits of convergence’ presents evidence for considering the convergence as due not merely to similar physical demands of the marine environment, but to dynamic interactions between cephalopods and vertebrates since the late Palaeozoic. The convergence was set on its way when the two groups, independently of each other, acquired locomotory methods that allowed them to increase in size. The loss of the chambered shell was an evolutionary response to the needs of increased mobility and to the need to go deeper as vertebrate predators pushed out into oceanic waters.
In their paper A lateral line analogue in cephalopods: water waves generate micro phonic potentials in the epidermal head lines of Sepia and Lolliguncula, authors, Bernd U. Budelmann and Horst Bleckmann, write that epidermal lines on their heads and arms are an analogue to the lateral lines of fish and aquatic amphibians and thus are another example of convergent evolution between a sophisticated cephalopod and vertebrate sensory system.
SECTION 5: COMMUNICATION
Research by Benjamin Burford and Bruce Robison of Stanford University published in March 2020 in the journal Proceedings of the National Academy of Sciences documents the Humboldt squid’s ability to subtly glow – using light-producing organs in their muscles – which can create a backlight for shifting pigmentation patterns on their skin. They may be using these changing patterns to signal one another.
Footage confirmed that squid’s pigmentation patterns do seem to relate to specific contexts.
Some patterns were detailed enough to imply that the squid may be communicating precise messages – such as “that fish over there is mine.” There was also evidence that their behaviours could be broken down into distinct units that the squid recombine to form different messages, like letters in the alphabet. The researchers emphasize that it is too early to conclude whether the squid communications constitute a human-like language.
Research by Benjamin Burford and Bruce Robison of Stanford University published in March 2020 in the journal Proceedings of the National Academy of Sciences documents the Humboldt squid’s ability to subtly glow – using light-producing organs in their muscles – which can create a backlight for shifting pigmentation patterns on their skin. They may be using these changing patterns to signal one another.
Footage confirmed that squid’s pigmentation patterns do seem to relate to specific contexts.
Some patterns were detailed enough to imply that the squid may be communicating precise messages – such as “that fish over there is mine.” There was also evidence that their behaviours could be broken down into distinct units that the squid recombine to form different messages, like letters in the alphabet. The researchers emphasize that it is too early to conclude whether the squid communications constitute a human-like language.
SECTION 6: THE SQUID EYE
Unlike the vertebrate eye, a cephalopod eye is focused through movement, much like the lens of a camera or telescope, rather than changing shape as the lens in the human eye does.
Squids have polarization vision, which may be an analogue of colour vision. Detecting reflections of fish scales by differences in polarization may be comparable to detecting the differences in hue with color vision, or be a method of increasing the contrast in the image.
Ian Gleadall writes that ‘squids probably use this polarization system to break the ‘silver mirror’ anti-predation reflective-colouring of fish scales. The cephalopod eye also has an incredible illumination range under which it can operate, from almost complete darkness to bright sunlight. In this, the cephalopod eye is far superior to the human eye’.
Squids, with only a single photoreceptor, have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide “color-blind” animals with a way to distinguish colors.
The unusual U and W shaped pupils of cephalopods allow light into the eye from many directions, which spreads out the colors and allows the creatures to determine color, even though they are technically colourblind.
Unlike the vertebrate eye, a cephalopod eye is focused through movement, much like the lens of a camera or telescope, rather than changing shape as the lens in the human eye does.
Squids have polarization vision, which may be an analogue of colour vision. Detecting reflections of fish scales by differences in polarization may be comparable to detecting the differences in hue with color vision, or be a method of increasing the contrast in the image.
Ian Gleadall writes that ‘squids probably use this polarization system to break the ‘silver mirror’ anti-predation reflective-colouring of fish scales. The cephalopod eye also has an incredible illumination range under which it can operate, from almost complete darkness to bright sunlight. In this, the cephalopod eye is far superior to the human eye’.
Squids, with only a single photoreceptor, have a monochromatic view of the world, can achieve color discrimination. An off-axis pupil and the principle of chromatic aberration (where different wavelengths come to focus at different distances behind a lens) can combine to provide “color-blind” animals with a way to distinguish colors.
The unusual U and W shaped pupils of cephalopods allow light into the eye from many directions, which spreads out the colors and allows the creatures to determine color, even though they are technically colourblind.
SECTION 7: GIANT SQUID, THE KRAKEN OF NORSE LEGEND
Documentary footage of giant squids, the whales who hunt them will be included in this section (as will CG animated sequences).
That an animal as large as a Giant Squid remained elusive for so long points to the fact that so little is known about life in the oceans.
Earliest reports date from the time of from Aristotle and Pliny, with the latter referring to arms of thirty feet in length.
In his book The Search for the Giant Squid, author Richard Ellis writes that the squid is a real life enigma. They are the stuff of seafarers’ tales-Herman Melville wrote about them in Moby Dick in 1851. It was not until 1861 that the first confirmed specimen was observed at sea by the crew of the French warship Alecton of the Canaries. They brought a section of its body to Tenerife.
In 1856 Danish scientist Japetus Steensrup named the giant squid Archieteuthis. In 1873 tentacles, including one of 19-feet, were hacked off a living Archieteuthis by a Newfoundland fisherman who brought it to the attention of the Reverend Moses Harvey who had it photographed along with its beak. The largest known specimen, at 57 feet, was washed ashore in New Zealand in 1887.
Richard Ellis writes that squids’ light producing photophores can be used to prevent a predator from picking out its silhouette against a sunlit surface. It can illuminate its underside, effectively eliminating its shadow.
Some species can emit a cloud of luminescent bacteria as a flashing pseudomorph, designed to confuse a potential predator.
Like most deep-sea squid, Giant Squid have light organs called photophores. The photophores at the tip of two stubby arms are unique.
The size and shape of lemons—each nestled within a retractable lid like an eyeball in a socket—they are the largest photophores known to science. They may function as searchlights.
Giant squids have the largest eyes in the animal kingdom, reaching 400mm in diameter.
In 2012, a juvenile giant squid was finally filmed live in its natural habitat. Dr Edith Widder and associate colleague Nathan Robinson found and filmed the giant squid by placing glowing lures outside of a submersible to mimic jellyfish they prey upon.
The footage finally confirmed that giant squids are active predators that assess and then attack its prey.
Documentary footage of giant squids, the whales who hunt them will be included in this section (as will CG animated sequences).
That an animal as large as a Giant Squid remained elusive for so long points to the fact that so little is known about life in the oceans.
Earliest reports date from the time of from Aristotle and Pliny, with the latter referring to arms of thirty feet in length.
In his book The Search for the Giant Squid, author Richard Ellis writes that the squid is a real life enigma. They are the stuff of seafarers’ tales-Herman Melville wrote about them in Moby Dick in 1851. It was not until 1861 that the first confirmed specimen was observed at sea by the crew of the French warship Alecton of the Canaries. They brought a section of its body to Tenerife.
In 1856 Danish scientist Japetus Steensrup named the giant squid Archieteuthis. In 1873 tentacles, including one of 19-feet, were hacked off a living Archieteuthis by a Newfoundland fisherman who brought it to the attention of the Reverend Moses Harvey who had it photographed along with its beak. The largest known specimen, at 57 feet, was washed ashore in New Zealand in 1887.
Richard Ellis writes that squids’ light producing photophores can be used to prevent a predator from picking out its silhouette against a sunlit surface. It can illuminate its underside, effectively eliminating its shadow.
Some species can emit a cloud of luminescent bacteria as a flashing pseudomorph, designed to confuse a potential predator.
Like most deep-sea squid, Giant Squid have light organs called photophores. The photophores at the tip of two stubby arms are unique.
The size and shape of lemons—each nestled within a retractable lid like an eyeball in a socket—they are the largest photophores known to science. They may function as searchlights.
Giant squids have the largest eyes in the animal kingdom, reaching 400mm in diameter.
In 2012, a juvenile giant squid was finally filmed live in its natural habitat. Dr Edith Widder and associate colleague Nathan Robinson found and filmed the giant squid by placing glowing lures outside of a submersible to mimic jellyfish they prey upon.
The footage finally confirmed that giant squids are active predators that assess and then attack its prey.
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