St. John’s Arms

Today we head back to Gotland for another ancient knotlike symbol.  The Saint John’s arms is a square with loops at each edge.  The shape is actually not a knot but an unknot: if you pulled at it you would discover that it is a torus which has been twisted.

Fornsalen Museum, Visby ( Gotland ). Picture stone with Saint John’s Arms Knot (photo by Wolfgang Sauber)

The symbol appears carved on a 1500 year old image stone from Hablingbo, on the island of Gotland (a Swedish Island in the Baltic Sea).  Ever since then it has appeared throughout the Scandinavian/Baltic world to demark sights of interest.  Although it is especially common in Finland (where it gained a reputation for warding off evil), the Saint John’s arms can be found blazoned upon cultural attractions throughout Belarus, Denmark, Estonia, Finland, Iceland, Lithuania, Norway, and Sweden.

Rana museum, department of Natural history in Mo i Rana (Nordland, Norway)

From its obscure Scandinavian roots, the Saint John’s arms vaulted into international fame during the 80s.  Originally Apple computer utilized the “open apple” and “closed apple” as its command keys (I even remember these from my old Apple IIe and my halcyon days of adventuring in the realms of Ultima).  In 1984, when the Macintosh personal computer was introduced, Steve Jobs decided that using the apple for shortcut commands was denigrating the brand.  According to Apple insider Andy Hertzfeld, when Jobs saw how many apple commands were in an early version of MacDraw he peremptorily told the design team, “There are too many Apples on the screen! It’s ridiculous! We’re taking the Apple logo in vain! We’ve got to stop doing that!”  The bitmap artist, Susan Kare, flipped through her dictionary of international symbols until she found one that easily translated into 16 bit-resolution.  It was the Saint John’s arms symbol—which the symbol dictionary said indicated camping grounds in Sweden.

So today the Saint John’s arms, a mysterious Viking symbol carved on a weird rock on a haunted island, is in use everywhere that Apple computers are.

The Blanket Octopus

An Adult Female Blanket Octopus

“Blanket octopus” sounds like an endearing nursery game, but the blanket octopuses are actually pelagic hunters which have adapted to living in the ultra-competitive environment of the open ocean.  There are four species of blanket octopuses (Tremoctopus) which can be found ranging from the surface to medium depths of open tropical and subtropical seas worldwide.  Because they often live far from any land, some of the methods which other octopuses use to escape predators do not work very well for them.  Fortunately Blanket octopuses have adapted in their own unique bag of tricks.

An Adult Female Blanket Octopus

Blanket octopuses are named after the distinctive appearance of adult female octopuses which grow long transparent/translucent webs between their dorsal and dorsolateral arms.  Blanket octopuses use these webs as nets for hunting fish, but they can also unfurl and darken their nets in order to appear much larger than they actually are.  Since blanket octopuses do not produce ink and can not camouflage themselves as rocks, coral, or sand, they rely heavily on their blankets.  As a last resort they can jettison the blankets as a decoy and jet away while the confused predator attacks the highly visible membranes.

Blanket octopuses exhibit extreme sexual dimorphism.  Whereas the female octopus can grow up to 2 meters (6 feet) in length, the male octopus is puny and does not grown longer than a few centimeters (1 to 2 inches).  Males store their sperm in a modified quasi-sentient third right arm, known as a hectocotylus.  During mating this arm detaches itself and crawls into the female’s reproductive vent.  As soon as the hectocotylus is detached the male becomes unnecessary and dies.

Male Blanket Octopus

Tiny males and immature females do not have blankets, but they utilize another trick to protect themselves.  Because they hunt jellyfish and other hydrozoans, the little octopuses are immune to the potent venom of the Portuguese man o’war.  The octopuses tear off stinging tentacles from the man o’war and wield them in their tentacles like little whips to ward off predators.

An amazing illustration of a blanket octopus sheltering in a Portuguese man o’war’s tentacles

Abyssal Giants in the Southern Ocean

The Mountains of Antarctica as seen from the Southern Ocean

The great Southern Ocean which swirls in a clockwise circle around Antarctica is home to many of the Earth’s largest animals.  Blue whales come here to gorge on vast schools of krill. Among the icebergs and the towering waves, southern elephant seals (the largest member of the order Carnivora) fight duels to build their harems, and highly intelligent killer whales hunt together in pods.  There are populations of sperm whales living in the Southern ocean as well and these leviathans dive to the cold floor of the world hunting for the world’s largest mollusk, a huge cephalopod which can only be found in the Southern Ocean.  In fact this bizarre creature, the colossal squid (Mesonychoteuthis hamiltoni) is also the world’s largest invertebrate.  Also known as the Antarctic squid or the giant cranch squid, the colossal squid lives in the abyssal depths.  Unlike other squid, the colossal squid does not have tentacles–its powerful arms are studded with sharp hooks (much like the long-extinct belemnites).  Some of these hooks swivel while others have three barbs in the manner of a fish spear.

The Colossal Squid (Mesonychoteuthis hamiltoni)

The measurements of the colossal squid are staggering.  Its eye alone (the largest of any known creature) measures 27 centimetres (11 in).  A fully grown adult squid is estimated to be 12–15 metres (39–49ft) long.  Although giant squid have longer tentacles, the colossal squid a long stout mantles and are thus much more massive. Their upper weight limits are unknown but are well over 500 kg (+1000 lbs).

The colossal squid is believed to be an ambush predator, which lurks in the depths waiting for chaetognatha, other squid, and benthic fish (such as the Patagonian toothfish) to pounce upon.  It is hypothesized that they have a slow metabolism and do no need great reserves of food (unlike the energetic endothermic sperm whales which prey on them).  The colossal squid are believed to be sexually dimorphic—the females become much larger than the males.

A rare specimen of colossal squid

There is a reason that so much of this article is couched in ambivalent language such as “estimated”, “believed” and “probably”:  colossal squid live in an environment where humankind can barely venture.  The colossal squid are fast enough and clever enough to usually evade our nets, lines, and traps (although fishermen trying to catch Patagonian toothfish hooked a 450 kg (990 lb) specimen which was about 39 feet (13 m) long).  Additionally our submarines and submersible robots are too slow and noticeable too stalk the squid in the abyssal depths.  Other ocean creatures do not suffer from the same problem.  Juvenile colossal squid are eaten by beaked whales, elephant seals, sharks, toothfish, and even albatrosses, however the adult squid are so large that only massive sleeper sharks and giant sperm whales can threaten them.  Sperm whales are often covered with scars from their battles with the giants but the whales easily have the upper hand.  Sperm whale stomachs have been found filled with hooks and beaks (which coincidentally were much larger than those found on the largest squid specimens recovered by humans to date).