Thinking Citizen Blog — Wildlife (I) the Giant Squid — Huge Eyes, Nasty Beaks, Lots of Ammonium Chloride

Thinking Citizen Blog — Wednesday is Climate Change, the Environment, and Sustainability Day

Today’s Topic: Wildlife (I) the Giant Squid — huge eyes, nasty beaks, lots of ammonium chloride

Should we care about the future of the Giant Squid? Or the black rhinoceros? Or the spotted owl? Does biodiversity really matter? My answer is yes. But let’s not get into why right now. Let’s focus on a more specific question. Why start a wild life series with the giant squid? Well, because last week, on Science Day, I wrote about the octopus and then I thought why not have an “environment day” series on animals as I have had ones on mountains and rivers? And if the octopus gave me the idea, why not start with its cousin, its fellow cephalopod, the squid. So here goes. Experts — please chime in. Correct, elaborate, elucidate.

THE “COLOSSAL SQUID” VERSUS THE “GIANT SQUID” — and by the way what do they taste like?

1. How big is a “colossal squid” (the largest of all invertebrates)? The image above may help give you a sense of what it would be like to meet one. Maximum weight has been estimated to be 1300–1500 pounds. Maximum length: 33–46 feet. The colossal squid lives in Antarctic waters. The largest specimen is in the Museum of New Zealand and weighs 1091 lbs.

2. How about the “giant squid”? Well, it is almost as big as the “colossal squid” and can be found all over the world’s deep ocean — from the North and South Atlantic to the North and South Pacific. Usually found near continental and island slopes.

3. “Like all squid, a giant squid has a mantle (torso), eight arms, and two longer tentacles (the longest known tentacles of any cephalopod). The arms and tentacles account for much of the squid’s great length, making it much lighter than its chief predator, the sperm whale.”

NB: “Giant squid and some other large squid species maintain neutral buoyancy in sea water through an ammonium chloride solution which is found throughout their bodies and is lighter than seawater. This differs from the method of flotation used by most fish, which involves a gas-filled swim bladder. The solution tastes somewhat like salty liquorice/salmiak and makes giant squid unattractive for general human consumption.”

LARGEST EYES OF ANY LIVING ANIMAL — 11 inches in diameter (versus 9.4 inches for a basketball)

1. “Only the extinct Ichthyosaurs are known to have had larger eyes.”

2. Human eyes can only detect light to a depth of 500 to 600 meters. Giant squid hang out at depths of 1000 meters.

3. “A large pupil allows the eye to collect every last photon of light in the incredibly deep and dark waters where it lives.”


1. “The inside surfaces of the arms and tentacles are lined with hundreds of sub-spherical suction cups, 2 to 5 cm (0.79 to 1.97 in) in diameter, each mounted on a stalk. The circumference of these suckers is lined with sharp, finely serrated rings of chitin. The perforation of these teeth and the suction of the cups serve to attach the squid to its prey. It is common to find circular scars from the suckers on or close to the head of sperm whales that have attacked giant squid.”

2. The giant squid’s “beak” (above) is sometimes called its “jaws” or its “mouth” and has been compared to a parrot’s beak. It cuts up the squid’s prey into nice digestible chunks.

3. Giant squid beaks are often found in the stomachs of its predator, the sperm whale — undigestible detritus.

NB: Unlike the octopus, the giant squid has a vestigial remnant of the ancestral mollusc shell. It is called a “gladius” after the Roman short sword. Also called a “pen” and, composed of chitin, it “serves as a site of attachment for important muscle groups and as a protective barrier for the visceral organs.” Also referred to as an “internalized shell.”

Colossal squid

Giant squid

Construction and Composition of the Squid Pen from Doryteuthis pealeii — PubMed

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Please share the coolest thing you learned in the last week related to climate change or the environment. Or the coolest, most important thing you learned in your life related to climate change that the rest of us may have missed. Your favorite chart or table perhaps…

This is your chance to make some one’s day. Or to cement in your own mind something that you might otherwise forget. Or to think more deeply than otherwise about something dear to your heart.