Sunday, 2 October 2016

Really Gigantic Squid? 1. Official Records

There is probably no apparition more terrifying than a gigantic, saucer-eyed creature of the depths with writhing, snakelike, grasping tentacles, a huge gelatinous body, and the powerful beak of a humongous seagoing parrot. Even the man-eating shark pales by comparison to such a horror.
(Richard Ellis, The Search for the Giant Squid, 1998)
     No doubt this is the reason why, as I commented in another article, people are more likely to encounter a living giant squid in fiction than in real life. Most people don't realize how recent has been our fascination with this monster. It was only scientificly described in 1856, and first observed at sea in 1861. Were it not for its habit of periodically dying en masse and being washed ashore, it may well have remained as legendary as the sea serpent.
     But the aim of the next two articles is to examine the claims that there exist individuals far, far bigger than those known to science.
     For this, I am reliant for most of my information on two omnibus books. The first is that of Richard Ellis, cited above. He is sceptical of the claims, but open minded. The other is In the Wake of the Sea-Serpents (1965) by Bernard Heuvelmans, who is one of the main proponents of the super-squid speculations. His book includes a major chapter on the history of the giant squid, a more expanded account of which was published in 1997 as The Kraken and the Colossal Octopus.
     Also, because of the large number of measurements quoted, I have reluctantly suspended my normal custom of quoting in both metric and imperial measures. If you are unfamiliar with imperial measures by reason of your age or nationality, feet can be converted to metres by dividing by 3.28.

     Of course, Scandinavia had always had the legend of the kraken, and whalers were familiar with large tentacles and lumps of squid vomited up by sperm whales. The first scientist to take them seriously was a Frenchman called Pierre Denys de Montfort in 1802, even though he imagined it was really a colossal octopus. Unfortunately, he was rather uncritical in the information he accepted, and that was to be his undoing. The animal was first named by the Danish Professor Japetus Steenstrup in 1856, and in 1861 the French warship, Alecton happened to see, and attempt to capture, a huge squid at sea. Then, in the 1870s, a large number of the monsters were washed up, dead or dying, on the beaches of Newfoundland, Labrador, and Nova Scotia. It is noteworthy that most of them were recorded and measured by non-scientists. The local fishermen had a habit of cutting them up for dog food or fish bait.

What is it?
     Squids are cephalopods, which means they are related to the octopus, cuttlefish, and nautilus, and cephalopods are molluscs, among which are included the snails, slugs, and bivalves. Unlike octopuses, which can swim, but tend to lurk on the sea bottoms, squid are swimmers in the open water. Most are small, but a gradation in size exists up to the largest. Moroteuthis robustus is sometimes called the Pacific giant squid, but its maximum length is "only" 19 feet. The real giant squid, Architeuthis dux appears to be a cosmopolitan species, which may breed in the tropics, but the really big specimens have all hailed from the extreme bounds of its range, the cold waters of the North Atlantic or the depths around New Zealand. In the Southern Ocean, around Antarctica, its place is taken by the colossal squid, Mesonychoteuthus hamiltoni, whose arms and tentacles are shorter and more robust than those of the giant squid, although its body is of comparable size. However, despite its common name, and contrary to what you will read on the internet, it is not noticeably larger than the giant squid. Both exhibit such a range of body size that it is too close to call.
    Knowledge of the biology of the giant squid is very limited. It appears to be solitary in nature, and to lurk in the depths of the ocean, hundreds of feet below the surface, perhaps going even lower during daylight hours. Its eyes are not the largest in the animal kingdom for nothing. Any individual found on the surface, if not dead or dying, is unlikely to be very healthy.
     The enemy of all squid is the sperm whale, or cachalot. Annually, it has been estimated that the world's one and a quarter million sperm whales consume 100 million tons of squid! That's more than the weight of all the human beings on earth. The only indigestible part of a squid is its horny beak, of which it is not unusual to discover five to seven thousand in the bowels of a sperm whale. (The record was 28 thousand.) Of these, those of the giant squid are a minority (0.26% in one sample), but they would obviously form the pièce de résistance. They must be consumed as the result of titanic battles hundreds of feet down, in complete darkness, with the whale holding its breath.
     How the whale does it is a mystery. One theory is that it stuns the squid with a sonic boom. What is certain is that its jaws are suitable only for holding, not biting. The peg-like teeth exist only on the lower jaw, which cannot move sideways. Freshly consumed, undigested giant squid have been found in their stomachs - always only one per whale - whole, without any tooth marks or punctures. One was even still alive!

What are we measuring?
There is nothing familiar or comforting about a spindle-shaped creature with a collection of writhing arms at one end and a pointed tail at the other. It seems to have no head - at least where we expect to find one - but it does possess huge, lidless eyes; eight grasping arms studded with toothed suckers, whip-like tentacles with which to grasp its unfortunate prey; and a beak where no creature is supposed to have a beak - between its arms. (Ellis, op.cit.)
     So, in order for us to understand the terminology, and know exactly what is being measured, let us start with this diagram, which was taken from the Smithsonian website.
     The funnel is used to squirt water, and thus move the squid by a sort of jet propulsion. Although it can "swim" in any direction, the fins are actually on the tail, and the beak sits in the mouth in the centre of the arms. The mantle is the outer covering which, in the related nautilus, and the distantly related snails, would secrete the shell. The distance between tail and beak is the head and body measurement, but the mantle length is considered the most reliable measurement for comparison purposes.
     Radiating out from around the mouth are eight arms, or short tentacles, each with a double row of toothed suckers along their entire length. In length, they are similar to the combined head and body, but much variation exists. On either side are two feeding tentacles (hitherto called simply "tentacles" to distinguish them from the "arms") which, even in the largest specimens, are no thicker than a man's forearm, furnished at the end with two paddle-like clubs bearing suckers. The idea is that these shoot out to seize the prey, then reel it in to be grasped by the eight arms, and borne to the terrible beak.
     These two tentacles are very long. A specimen in the South Australian possessed tentacles 24 feet long attached to a body of total length of only 6 feet. A good rule of thumb is that total length = mantle length x 4.4, but much variation exists. The point to be made is that, when you include them in the measurement, as is usually the case, they essentially double the effective size ie head, body, and tentacles.
     They can also be stretched - like rubber bands. However, too much should not be made of this. I don't think it happens very often that a fisherman, after measuring a 20 foot tentacle attached to a stranded carcass, calls out to his companion, "All right, Fred, I'll take this end and pull, and we'll see how far we can make it stretch."

How Big?
     The longest specimen scientifically measured was washed up at Lyall Bay in New Zealand in 1887. A local fisherman called Smith approached zoologist, T.W. Kirk and told him he had paced it off at 62 feet. But when Kirk examined it - in heavy rain and a driving wind - he found it was "only" 55 feet 2 inches, but the mantle length was a mere 5 feet 11 inches.
     On the other hand, the biggest appears to have been the one caught at Thimble Tickle, Newfoundland in  November 1878. Yes, caught. Although it was on its last legs, so to speak, it was nevertheless alive when three fishermen discovered it. It was aground close to shore, and thrashing its appendages in an effort to escape. They threw a grapple onto it, then moored it to a tree with a stout rope, and when the tide went completely out, it expired. But before they cut it up for dog food, they measured its body as 20 feet from tail to beak, with its long tentacles 35 feet in length.
     Personally, I am always a bit suspicious of round numbers. However, if a 20 foot body sounds a bit over the top, there have nevertheless been several specimens with bodies a few feet shorter. (The Wikipedia provides a nice list.)

  • Grand Banks, Dec 1874:                            body 12 - 13 feet, total length 42 - 43 feet
  • Grand Banks, Oct 1871:                             body approximately 15 feet
  • Three Arms, Newfoundland, Dec 1878:  body 15 feet
  • Bonavista Bay, Dec 1872:                          body 14 feet, total length 32 feet.
  • West St Modent, 1875:                               body 15 feet, total length 37 feet

     Ironically, it would appear from these that a very big body goes with tentacles proportionally slightly shorter than in smaller specimens. But don't let it be said, as the Smithsonian claims, that the maximum mantle size is 7.4 feet, and the maximum total length 43 feet.

But what does "maximum size" mean, anyway?
     The "maximum size" of any species is a somewhat artificial statistic. After all, the maximum size of human beings is 8 ft 11 in, the height of the unfortunate Robert Wadlow (1918-1940), who suffered from pituitary giantism. However, we know that 6 ft 8 in is probably the maximum non-pathological height, and even that is uncommon. Probably every species has its freakishly large individuals.
     Also, unlike mammals, "cold blooded" animals usually continue to grow throughout life, so the oldest ones are normally the largest. Thus, you would expect a big male saltwater crocodile (Crocodylus porosus) to measure about 17 feet, with 20 feet the normal outside limit, while the one shot near Normanton in 1957 would have owed its length of 28 ft 4 in to a combination of age and an unusual growth pattern.
     Nevertheless, most animals, like the abovementioned crocodiles, tend to grow to what might be called a basic adult size, and then growth slows down, even if it doesn't stop. The giant squid appears to buck that pattern. Ellis provides an appendix in his book listing giant squid specimens, mostly strandings. In 80 cases the total length was recorded, so I plotted the size of these against number, and was interested to discover that numbers were more or less constant throughout all size categories except the highest. The median length was about 27 feet, with 50 of the 80 being 30 feet long or less, but with five more than 50 feet. This is consistent with a species whose growth rate remains more or less steady throughout life, with the very big ones dropping off the scale as they perish.
     And no, the smaller ones were not necessarily immature. A female with a 6 foot body and 24 foot tentacles contained eggs. So did one with a mantle length of  5 ft 9 in. Sexual maturity probably occurs before the average size is achieved.
     There is one other point to remember. Exceptionally outsized land animals tend to get noticed by humans, and quite frequently shot. But the same does not apply to non-air-breathing denizens of the depths. It would be the merest coincidence if the largest squid ever just happened to get washed ashore. There must be larger ones down there. It was this logic, and an extrapolation of squid sizes - something like the study I just did, but in more detail - which made fisheries ecologist, Charles Paxton determine that it is possible for giant squid to occasionally reach 66 feet, or 20 metres, and to have mantles 10 feet long (well, that has already been established).
     Unlikely, responded Dr Stephen O'Shea. If squid as large as that really existed, their beaks would have been found, either in sperm whale stomachs or from sea bed sampling. I beg to differ. In the first place, such squid would be extremely rare. I don't know how many beaks have been found in sea bed sampling - after all, they do live in the deep parts of the open ocean - but with respect to sperm whales, an obvious problem arises. Bearing in mind that the whales swallow squid whole, instead of tearing them to pieces like sharks, a point must be reached where the individual is simply too big to eat.
     Ellis and Heuvelmans had radically different ideas as to the weight of the largest squid. I intend to take a middle path, and base it on the principle that volume increases according to the cube of the dimension. In other words, if you double the size of anything, you double its length, breadth, and depth, which means that its weight is increased eight fold.
     Now, in 1955 a giant squid found in the stomach of a 47-foot sperm whale was 34 ft 5 in long, and weighed 405 lb. Another one caught off Norway had a length of 33 feet and weighed 485 lb. By extrapolation, a 66-footer would therefore weigh between 1.2 and 1.7 tons. That, of course, assumes the proportions are the same. However, the rules of allometry mean that larger individuals and species are slimmer, with longer appendages than their smaller cousins, so perhaps a ton would be a more appropriate estimate. That's still an awful lot to fit in a whale's stomach.
     But that's not all. A squid which had lost both its long tentacles, but which had a mantle length of 5 ft 9 in, weighed 371 lb. But since the mantle of the Thimble Tickle monster appears to have been three times as long, it should be 3 x 3 x 3 = 27 times as heavy, or close on 4½ tons - say 3½ tons if it were slim, or its size overestimated. One wonders exactly how big was the fishing boat that grappled it, and how far it had to be dragged, even accepting that squids are buoyant in water.  But even a mantle length of 12 feet would imply a weight of about a ton. Here we note that the Grand Banks squid of October 1871 (no. 22 on the Wikipedia list) with its 15 foot body length had a weight cited as 2,000  lb. And if the tentacles of these massive specimens were in the same proportion as smaller squid, they would bring the total length to 60 feet.
    No, Dr O'Shea, there almost certainly are 60 footers down there. The big question is whether there are any 100 footers or 150 footers, as some people allege. We shall examine that in Part 2.

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The Possum Book

I am pleased to provide a link to a website of a friend of mine, Robyn Tracey, who has written a fascinating story about her dealings with brush-tailed possums in the outer suburbs of Sydney. You can download the book for free, or read it on the site. Go to: The Possum Book.