‘I cannot think of the deep sea without shuddering at the nameless things that may at this very moment be crawling and floundering on its slimy bed.’ So wrote H. P. Lovecraft, American horror author who created the infamous Cthulhu and other monstrous creatures. And if he had ventured to the ocean abyss, he wouldn’t have been disappointed – there are many foul, disgusting and (above all) amazing creatures found down there that wouldn’t have felt out of place in one of Lovecraft’s own stories.
If a requirement for being a deep-sea monster is to be large and terrifying, then the giant squid certainly meets those criteria. At 13 metres long or more (there have even been unconfirmed reports of individuals measuring 20 metres) and weighing up to two tonnes, the giant squid is not something you would want to suddenly bump into in the perpetual gloom of the ocean deep. Their suckers, which are the size of dinner plates, are so powerful they can leave permanent scars on their main predator, the sperm whale. This is the animal that probably inspired the mythological kraken (which I have already covered on the blog here if you want to know more).
The giant squid is a cephalopod – that’s the scientific name for the squids, octopuses and their more obscure relatives. For a while, the giant squid was considered the largest cephalopod in the sea, but we now know there is an even bigger relative down there: the colossal squid. If the giant squid is considered an alien and mysterious creature, then that doubly applies to the colossal squid. Though it is the largest invertebrate in the world, we know almost nothing about it. And until technological advances allow us to better explore its distant, hostile environment, it’s likely to stay that way for quite some time.
Most denizens of the deep sea are ugly, twisted creatures. They have strange bodies that would have no place in the world above. But a few animals break that trend, including this cephalopod: the strangely cute and endearing Dumbo octopus.
Yes, it is named after the Disney elephant of the same name that could fly using his oversized ears. In a similar fashion, the Dumbo octopus uses its own ‘ears’ (they’re actually modified fins) to glide gracefully through the darkness, which is probably an energy-conserving method of locomotion.
The animal with the largest eyes in relation to its body size is the scary-looking vampire squid: each one is about 2.5cm in diameter, which, considering that the entire animal is only 30cm long, means that one eye accounts for around a twelfth of the squid’s body length.
The scientific name of the vampire squid is Vampyroteuthis infernalis, which literally means ‘vampire squid from Hell’. This, however, is a poor name. For a start, it doesn’t have any vampiric habits (it certainly doesn’t suck blood; it eats detritus and plankton) and it isn’t even a squid – it belongs in its own unique order of cephalopods, separate from both the squid and octopus.
Many cephalopods can squirt ink to confuse and disorientate predators so they can make a quick getaway, but the darkness of ink would be pretty useless in the darkness of the deep sea. The vampire squid squirts light instead: sticky, bioluminescent mucus from the tips of its arms, which can remain lit for up to ten minutes. As this light dazzles the potential predators, the vampire squid slips away back into the gloom.
Occasionally, you come across an animal that looks so strange and unlike anything else that it can be hard figuring out what it actually is. Looking at the sea pig is probably one of those times. Elsewhere, the name of an animal might give you some clues, but the name ‘sea pig’ is so blatantly inaccurate that it’s of no help whatsoever.
What you are actually looking at here is a sea cucumber. Unlike other sea cucumbers, which tend to wriggle and squirm around, sea pigs have actual legs for locomotion. They wander across the abyssal floor, sifting through the organic waste that falls from the sunlit waters above to find sustenance. They often congregate in vast ‘herds’ of some several hundred individuals, although that seems more reminiscent of cattle rather than sheep…
You can find an isopod quite easily in your garden. Just lift up a few stones and you will probably find a few woodlice scurrying around under them. But isopods are also very common in the ocean, and at the very bottom, there is a giant.
This is Bathynomus giganteus, the aptly-named giant isopod. It can reach nearly 50 cm in length and weigh over a kilogram. The fact that it looks very much like your average woodlouse, albeit scaled up dramatically, gives it a creepy and otherworldly vibe. There isn’t much food at the bottom of the ocean, no matter what your diet preference is, so the giant isopod can go without a morsel for eight weeks or so. If it does find a food source, though, it can gorge itself so much that the animal finds it difficult to walk afterwards.
It has been said that the queen xenomorph first seen in James Cameron’s 1986 movie, Aliens, was based on a deep sea animal. Perhaps surprisingly, it’s a small transparent crustacean called Phronima that drifts aimlessly around.
But, like its supposed Hollywood progeny, Phronima is a parasite. Certainly, if you happen to be a salp, a tiny barrel-shaped planktonic animal, the presence of Phronima is very bad news indeed. Females attack salps, using their mouths and claws to eat the animal and hollow out its gelatinous body. Phronima then enters the now-empty barrel of the salp and lays her eggs inside. The paddling of her tiny fins pumps water through the salp’s severed ends, turning it into a miniature submarine to hunt down more prey. Any tiny creatures that get sucked inside the barrel are unable to escape again and are easily snapped up. The barrel also serves as protection to the female Phronima and her developing larvae.
The deep sea week continues tomorrow as we find out what the most heat-resistant animal on the planet is, and why it would need such an ability in the freezing ocean depths.