The Real Giant Squid Floats on Ammonia. Netflix's Below Left Out the Chemistry

Netflix released Below on 8 October 2026, a sea-monster series set in a Newfoundland outport, and within two days Google Trends showed US searches for “giant squid” at roughly four times their September level. The creature, which the show calls Mudder, is a giant cephalopod. Netflix brought in Dr Annie Mercier, a marine biologist at Memorial University’s Ocean Sciences Centre, to check the science, and she was blunt about the monster leaving the water: “They don’t have the strength in their skeleton to do any harm to something that’s above water.”

What the real animal does have is chemistry. A giant squid is, in a meaningful sense, a 30-foot float filled with the same ion that gives a bottle of ammonia its bite. Scientists measured it in a giant squid from the same coast where Below is set, more than forty years before the show was made.

This article is about that measurement and the acid-base trick behind it. We take no position on the show, which is fiction and says so. Every figure below is linked to its source at the end; where we did our own arithmetic, we show the working and label it as ours.

The giant squid that was measured came from Newfoundland

Direct answer: yes, a real giant squid has been analysed, and it was caught alive off Newfoundland. Its body fluids were packed with ammonium.

In 1979 M. R. Clarke, E. J. Denton and J. B. Gilpin-Brown of the Marine Biological Association’s laboratory in Plymouth, England, published “On the use of ammonium for buoyancy in squids”. They sorted squids into two groups by density: squids that are heavier than sea water and must keep swimming to stay up, and squids that are nearly neutrally buoyant. In almost all of the second group they found large amounts of ammonium, which, in the paper’s words, “is mostly confined to special tissues where its concentration can approach half molar.”

The giant squid came into the paper because of a practical observation. Clarke and his colleagues noted that giant squid are regularly found floating dead or dying at the surface, and that “it has proved useless for bait because pieces float.” Then a sample arrived: pieces of arm and mantle “removed from a deep-frozen Architeuthis (taken alive off Newfoundland)”, supplied by F. Aldrich. The clear liquid that ran from the samples as they thawed was analysed alongside the other buoyant squids.

Two things stand out. Ammonium is the main positive ion in the mantle liquid, and sodium, the main positive ion of sea water, has dropped to 88 millimolar. Chloride is still the main negative ion, so what the squid carries is essentially a solution of ammonium chloride. A 2025 review in the Journal of Molluscan Studies by A. M. Pratt and F. E. Anderson still uses the same 338 figure for the giant squid family, with the ammonium stored in the mantle and arms.

How a salt makes a 30-foot animal float

Direct answer: an ammonium chloride solution weighs less than sea water at the same salt strength, so a body full of it needs no swim bladder and no constant swimming to stay up.

Fish usually stay up with a gas-filled swim bladder, which has to be adjusted as the fish changes depth because gas compresses. Many deep-sea squids use liquid instead. The trick is a swap: the animal pushes sodium ions out of certain tissues and holds ammonium ions in their place. The ammonium ion (NH₄⁺) is lighter than the sodium ion, so the liquid can carry about as many dissolved particles as sea water, which keeps it in osmotic balance with the ocean, while weighing less per liter. Clarke and his co-authors put it this way: the ammonium-rich solutions “are almost isosmotic with sea water but of lower density”.

The paper gives one worked value for a typical ammonium buoyancy fluid, the coelomic liquid of a cranchiid squid: about 475 millimolar ammonium at a density of 1.010. Woods Hole Oceanographic Institution gives typical sea water as 1,026 kilograms per cubic meter, a density of 1.026.

The lift column is our arithmetic, not a reported figure: 1.026 minus 1.010 is 0.016 grams per milliliter, or about 16 grams of upward push for every liter of buoyancy fluid. Sixteen grams per liter is small, which is why the squids that use it carry a lot of it; the paper reports that ammonium-rich tissue is extensive in these animals. The paper estimated that squids in at least 12 of the 26 families it reviewed reach near-neutral buoyancy this way. The 2025 review found that ammoniacal buoyancy “has arisen nine times across Oegopsida”, the group of open-ocean squids that includes the giant squid, and that depth distribution is correlated with which buoyancy method a squid uses.

Why the squid does not leak ammonia: pH 5.8

Direct answer: ammonia exists in two forms, and acidity decides which one wins. At the squid’s pH of 5.8, about 2,800 ammonium ions are present for every free ammonia molecule.

Ammonia (NH₃) is a gas that dissolves very well in water and slips easily through cell membranes. Ammonium (NH₄⁺) is the same molecule carrying one extra proton; it is charged, so it does not escape into the air and it crosses membranes far less readily. The two convert into each other constantly:

NH₄⁺ ⇌ NH₃ + H⁺

The balance point is the pKa of the ammonium ion, about 9.25 at 25 °C. PubChem lists the base constant of aqueous ammonia as pKb 4.751 at 25 °C, and 14 minus 4.751 is 9.249. At a pH equal to the pKa, the two forms are present in equal amounts. Every pH unit below it means ten times more ammonium than ammonia; every unit above it, ten times more ammonia.

The ratios are our arithmetic from the Henderson-Hasselbalch relation, not reported figures: the ratio of ammonia to ammonium equals 10 raised to the power of (pH minus 9.249). At pH 5.8 that is 10^−3.45, about 1 in 2,800, so the squid’s 338 millimolar ammonium sits alongside only about 0.12 millimolar free ammonia.

That is the squid’s whole trick. Acid traps the ammonia as an ion that cannot leak away, so the buoyancy stays in the animal. A 1995 review by J. R. Voight, H. O. Pörtner and R. K. O’Dor in Marine and Freshwater Behaviour and Physiology opens with the finding (“Some deep water squids are known to achieve neutral buoyancy by storing ammonium in their body tissues.”) and points to the physiology that may have made it possible: squids produce large quantities of ammonia from protein and “have very low blood pH’s which effectively remove ammonia from cells that produce it.”

The same equilibrium in a bottle of ammonium hydroxide

Direct answer: ammonium hydroxide is ammonia dissolved in water, sitting on the alkaline side of the same pKa, so most of it is free ammonia, which is why the bottle smells and the live squid does not.

Ammonium hydroxide, also sold as aqueous ammonia or ammonia water, is a solution of ammonia gas in water. A small fraction picks up a proton from water to become NH₄⁺ and OH⁻, which is why the solution is strongly alkaline. PubChem lists the pH of a 1.0 normal ammonium hydroxide solution as 11.6. On the table above, that puts about 224 free ammonia molecules beside every ammonium ion: the mirror image of the squid.

The squid and the bottle are 5.8 pH units apart, which is a factor of 10^5.8, about 630,000, in the ratio between the two forms. That figure is our arithmetic. Same molecule, same equilibrium, opposite ends of it. Concentrated grades such as 29 percent ammonium hydroxide carry far more ammonia than a 1.0 normal solution, which is why they are handled with ventilation and kept tightly closed.

Clarke and his colleagues used exactly this flip as a field test. They reported that when a squid tissue holds enough ammonium to make it buoyant, “a strong smell of ammonia can be detected when this tissue is placed in a strong sodium hydroxide solution and warmed.” Strong base pulls the proton off the ammonium (NH₄⁺ + OH⁻ → NH₃ + H₂O), the equilibrium jumps to the alkaline side, and the ammonia that the squid had locked away comes off as gas. Tissue from dense, non-buoyant squids such as Loligo gave no smell. It is a laboratory test, done with ventilation, and it is the same chemistry described in our caustic soda guide and our complete guide to ammonium hydroxide.

Sal ammoniac: the squid’s salt has an old name

Direct answer: the buoyancy salt is ammonium chloride, the compound that was sold for centuries as sal ammoniac.

Clarke’s team described the reference buoyancy liquid as “a solution rich in ammonium chloride”, and the giant squid table bears that out: ammonium is the main positive ion and chloride the main negative one. Ammonium chloride has one of the longest paper trails in chemistry. It was traded as sal ammoniac, the “salt of Ammon”, and the word ammonia was later built from that name. We tell that story in Who Discovered Ammonia?. The giant squid had been making the same salt in the North Atlantic the whole time.

Why giant squid keep turning up in Newfoundland

Direct answer: Newfoundland has a long record of strandings and catches, and ammonium buoyancy is one reason dead and dying giant squid reach the surface instead of sinking.

The first photographs of a giant squid were taken in St. John’s, in the autumn of 1873. On 26 October, fishermen off Portugal Cove cut a 19-foot tentacle from a living animal and brought it to Moses Harvey, a minister and amateur naturalist.

A few weeks later, in November 1873, a second giant squid was caught in a herring net in Logy Bay, about three miles from St. John’s. Harvey had it photographed in his home with its arms draped over a rail above a tub. The zoologist Addison Emery Verrill, who described the specimen, wrote on the print: “The tub is 38½ inches in diameter.” Harvey wrote in his journal: “A photograph could not lie and would silence the gainsayers.” A print is displayed at the Smithsonian’s National Museum of Natural History, according to The Scientist, which dates the photograph to 1874; the annotated print’s catalogue record and the Yale Peabody Museum give November 1873.

Part of that animal still exists. The Yale Peabody Museum holds specimen YPM IZ 9634: giant squid arms and suckers from Logy Bay, recorded as caught “in herring net, about 3 miles from St. John”, collected by Harvey and identified by Verrill, preserved in 70 percent alcohol. It has been in that jar for nearly 153 years, by our arithmetic from the November 1873 catch date.

The 1979 paper puts the two observations side by side: giant squid are regularly found floating dead or dying at the surface, and their tissue is buoyant enough that the pieces float. For size, the show’s fact-checker gives a sober figure: according to IBTimes, Mercier puts the average giant squid at around 33 feet in overall length, much of it in the two long feeding tentacles.

What Below leaves out

Direct answer: the real animal is weaker out of water than any sea monster, floats like a cork after death, and is built around an acid-trapped ammonium solution.

The jump from fact to fiction is the show’s job, and Mercier’s point about the skeleton stands: squids have no bony skeleton at all, only a thin internal pen, so out of the water they are soft and heavy. The chemistry adds a detail a horror series would probably rather skip. Hauled up on a fishing stage in the show’s fictional outport, a real Architeuthis would be the one sea monster that fails as bait because it floats, and whose tissue gives off a strong smell of ammonia once a chemist adds strong base and warms it.

What this means on a specification

Direct answer: the squid shows why the NH₃/NH₄⁺ balance matters. On an order for ammonium hydroxide, pin down the concentration, the grade and the paperwork.

Common questions

Why do giant squid float?

Giant squid hold large amounts of ammonium in their tissues in place of sodium. An ammonium chloride solution is lighter than sea water at the same salt strength, so the animal is close to neutrally buoyant without a swim bladder. A 1979 study of a giant squid caught off Newfoundland measured 338 millimolar ammonium in fluid from its mantle.

Is the giant squid in Netflix’s Below real?

The creature in Below, which the show calls Mudder, is fictional. Giant squid are real and are often recorded off Newfoundland, where the series is set. Netflix had Dr Annie Mercier of Memorial University check the science, and she has said a giant squid could not harm anything above the water.

Why are giant squid not eaten?

Their flesh carries a lot of ammonium, the ion that becomes ammonia when the pH rises. The 1979 Clarke study also notes that giant squid proved useless even as fishing bait, because the pieces float.

How does a squid keep ammonia from leaking out?

It keeps the fluid acidic. At the pH of 5.8 measured in giant squid mantle fluid, ammonium outnumbers free ammonia by about 2,800 to 1, by our arithmetic from the ammonium pKa of 9.25. The charged ammonium ion stays put, while free ammonia would escape.

What is the difference between ammonia and ammonium?

Ammonia, NH3, is a neutral molecule and a gas that dissolves easily in water. Ammonium, NH4+, is ammonia carrying one extra proton. Below pH 9.25 ammonium dominates; above it, ammonia dominates. Ammonium hydroxide, at about pH 11.6 for a 1.0 normal solution, is mostly dissolved ammonia.

Does ammonium hydroxide contain the same chemical as a giant squid?

Both contain ammonia and ammonium in equilibrium, but at opposite ends. The squid holds ammonium chloride at pH 5.8, so the ammonia stays bound as ammonium. Ammonium hydroxide is alkaline, so most of it is free ammonia. Adding a strong base to squid tissue shifts it to the ammonia side, which is how scientists tested for it.

References & Authoritative Sources

Squid measurements are from the peer-reviewed literature. Equilibrium constants and pH are from PubChem; sea water density is from Woods Hole. The show and its fact-checker are as reported by IBTimes. Our own arithmetic is labelled in the article.

1. On the use of ammonium for buoyancy in squids — M. R. Clarke, E. J. Denton and J. B. Gilpin-Brown, Journal of the Marine Biological Association of the UK 59: 259–276, 1979. Table 3 (giant squid arm and mantle), the bait observation, the sodium hydroxide test, the cranchiid reference fluid.
2. Evolution of ammoniacal buoyancy within oegopsid squids and its relationship with depth — A. M. Pratt and F. E. Anderson, Journal of Molluscan Studies 91(3), 2025. Nine origins; Architeuthidae ammonium in mantle and arms.
3. A review of ammonia-mediated buoyancy in squids (Cephalopoda: Teuthoidea) — J. R. Voight, H. O. Pörtner and R. K. O’Dor, Marine and Freshwater Behaviour and Physiology 25: 193–203, 1995.
4. Ammonia, compound summary — PubChem, US National Library of Medicine. Aqueous ammonia pKb 4.751 at 25 °C.
5. Ammonium hydroxide, compound summary — PubChem, US National Library of Medicine. pH 11.6 for a 1.0 N solution.
6. Sea water density description — Woods Hole Oceanographic Institution, U.S. GLOBEC. Typical sea water 1,026 kg/m³.
7. First Photo of Intact Giant Squid, 1874 — Catherine Offord, The Scientist. Moses Harvey, Portugal Cove, the tub photograph and Harvey’s journal.
8. Architeuthis dux, YPM IZ 009634 — Yale Peabody Museum, Division of Invertebrate Zoology. Logy Bay, Newfoundland, 25 November 1873, in herring net; 70 percent alcohol.
9. Logy Bay giant squid, 1873 — Wikimedia Commons record of the annotated print, citing F. A. Aldrich, Bulletin of Marine Science 49: 457–481, 1991. Date, place and Verrill’s annotations.
10. Giant squid tentacle saved by Moses Harvey — Wikimedia Commons record of the engraving from M. Harvey, Annals and Magazine of Natural History, 1874. Tentacle cut on 26 October 1873.
11. Netflix’s ‘Below’: The Truth About the Giant Sea Creature — Nobelle Borines, IBTimes UK, 9 October 2026. Release date, Mudder, Dr Annie Mercier’s fact-check and quotations.

What we stock for this chemistry

Key numbers and sources