classroom deep in the nautically inclined bowels of the Shedd Aquarium, 3-4 to a table, one 30
cm Longfin inshore squid to every two nautically inclined individuals. The decapodal specimens
had been provided by a nautically inclined and unnamed restaurant supplier.
Our appointed teacher spoke generally about squid. These cephalopods of the order Teuthida
boast bilateral symmetry, a mantle, and eight short, grasping arms assisted in the hunt by two
long, grasping tentacles. The primary body is enclosed in the mantle, which has a swimming
fin along each side, and the skin is coated in color shifting chromatophores, white signaling
aggression. When courting a female, the male maintains the heartily comforting red of the side
facing the female and the furious white of the side facing outwards, toward other males.
The squid’s underside is always lighter than the topside to provide camouflage from the
predators cruising above and the prey cruising below. They have vastly differentiated from their
mollusk ancestors, their bodies lengthening and condensing into a slim, aerodynamic predator
with advanced eyes similar to vertebrates and no ancestral shells. Instead, the squid’s structure
is supplied by a feather shaped pen made of chitin. Under the body are openings to the mantle
cavity, which contains the gills and openings to the excretory and reproductive systems. At the
front of the mantle cavity one finds the siphon, which the squid uses for locomotion via precise
jet propulsion. In this form of locomotion, water is sucked into the mantle cavity and expelled
out of the siphon in a fast, strong jet. The direction of the siphon can be changed, to suit the
direction of travel.
Post preamble, each group of two was supplied with an assignment, a secret to unlock from
their limply defrosted squid carcass. Our mission was to determine the method by which squid
hunted down their prey; our tools—probes, medical scissors, and tweezers. The exterior of a
longfin squid is obviously built for the hunt, its slimly lateral backwards mode of high speed
travel allows it to swoop down upon its prey from above, while its two tentacles, kept hidden by
its arms during travel, dart out and snag a small fish or crustacean, encasing it in its cartilaginous
suction ringed arms and tearing away flesh with its hard, sharp beak.
When a squid’s natural speed and ability is not enough to evade predators, it resorts to the sack
of ink it carries in its body, a dark pigment comprised of melanin and released into water when
the squid is threatened. The release of ink takes place in two stages—massive amounts of ink to
create a smoke screen, then a second release of pseudomorphic smaller clouds of ink with greater
mucus content which are attacked while the squid speedily slips away.
So here we are, hopefully having learned about squid and the wonderfully wacky ways in which
they work. Yessiree Bob, I tried to deliver straightforward information about squid, fascinating
animals that they are. There’s something slightly mystical and compelling about the squid
physiology. Fascinating animals.
Author: Ben M.