The Cockroach Catcher was on Cable Beach in Broome, Australia and found a creature he has never come across before and put the picture on Facebook. Luckily within a few minutes the answer came from his friend who generally knows most birds and plants. I raise my hat to him for knowing this: Chiton.
© 2018 Am Ang Zhang
I did some research and what I found was
most interesting:
Chitons
may be found mainly in the littoral surf zone. About 750 species of this
primordial mollusc class are known today. The largest one is Cryptochiton
stelleriwith 33 cm (about 14 in.), living on the American north western
coast.
In colloquial
language, chitons are also called coat-of-mail shells, their shell resembling
the segmental armour on a knight's gauntlet, though, as we shall see later, the
shell of a chiton is not segmented in the biological sense of the word.
Not only
chitons' shells are hard. Chitons, like snails, possess a rasp tongue (radula),
which they use to rasp food off the ground, if they are not among the few
carnivorous species, such as Placiphorella rubra
Chitons don’t have
anything we’d generally consider to be heads, and it’s long been thought they
don’t have brains, either, and instead sport a rudimentary, ladder-like nerve
network. Sumner-Rooney and Sigwart argue in their paper that chitons aren’t
really brainless, but rather have a brain that defies our expectations and
understanding.
Most
eyes in nature are made of organic molecules. In contrast, the Chiton’s eyes
are inorganic and made of the same crystalline mineral called aragonite that
also assembles the body armor. They enable the Chiton to perceive changes in
light and thus to respond to approaching predators by tightening their grip to
surfaces under water.
Using
a suite of highly resolving microscopic and crystallographic techniques, the
team unraveled the 3-dimensional architecture and geometry of the eyes,
complete with an outer cornea, a lens and an underlying chamber that houses the
photoreceptive cells necessary to feed focused images to the Chiton’s nervous
system. Importantly, the researchers found that aragonite crystals in the lens
are larger than in the shell and organized into more regular alignments that
allow light to be gathered and bundled.
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