Sunday 29 September 2013

Common Cuttlefish

Image: Eric Burgers
Sepia officinalis
They call it the Common Cuttlefish but I don't think there's anything "common" about any cuttlefish. In the land of the weird, cuttlefish reign supreme.

The land I refer to is Cephalopodia. All cephalopods are weird, be it bulbous octopods, streamlined squid or the Nautilus in its spiralling shell. You simply can't have that many tentacles and call it normal. I'm sure they're all intelligent enough to privately reflect on how weird it is to be a cephalopod. They probably write great works of philosophy on the subject.

Image: jome jome
But for me, Cuttlefish have always had something uniquely peculiar about them. It's not just those utterly inscrutable eyes with their W-shaped pupils that make approximately zero sense, it's something about their shape... their proportions...

Cuttlefish look for all the world like an alien's head, cut free from the neck and left to float with its bulbous brain case and tentacle beard. Perhaps they were on the losing end of a vicious cosmic war long ago. As punishment their very bodies were decimated and cast into the sea, existing now as Cuttlefish heads, Gorgonian lungs, Sea Squirt hearts and Sea Cucumber everything else.


Image: sarah faulwetter
Some kind of sense, anyway. Not Common Sense but then there's not much "common" about sense, either.

While cuttlefish are noted for their intelligence, one is forced to admit that the large body behind their eyes isn't actually full of brains. Rather it's the mantle, which contains all the digestive organs and such required for life.

Image: Philippe Guillaume
Those eyes remain totally alien, though.

When it comes to the delicate science of naming things, the Common Cuttlefish is one of the very first and original cuttlefish. No surprise there. It's big, it's common and it's found in Europe. This is all good stuff if you want to be among the first of your kind to get a scientific name.

Image: National Museums Northern Ireland
Up to 50 cm (20 in) long not including the head or tentacles.
Which is annoying because the head and tentacles are my favourite bit.
The Common Cuttlefish is actually one of the biggest in the world. A mantle length of 50 cm (20 in) is quite normal, and is two or three times the length of most other cuttlefish. These large sizes are attained in the cold of the North Sea and Baltic Sea, while those in the Mediterranean are more like 30 cm (1 foot) long.

Their range extends all the way down to South Africa, but unfortunately they don't seem to get smaller and smaller the further south you go until they disappear into nothing.

Image: National Museums Northern Ireland
So what about this scientific name? What does Sepia officinalis mean?

Sepia comes from the Greek word for cuttlefish. They'd be saying stuff like "sepia are so weird. They look like Medusa had a son and someone cut his head off and threw it into the sea and it grew fins and swam away." And I'd be like "YES." And a legend is born.

The word is now used to name the entire order to which all cuttlefish belong: Sepiida. If you make a cuttlefish really scared, it might release ink before running away. It's brown ink, rather than the black or blue-black stuff produced by octopus and squid. People used to take this ink and extract brown pigments from it, and this is where we get sepia colours and sepia photography from.

Our very nostalgia is painted in cuttlefish.

Video: daniele86sm

This usefulness is also why it's called officinalis. It means "belonging to an officina", and an officina was a storeroom in a monastery where things like medicinal herbs were kept. So now we have lots and lots of animals and plants called "Something officinalis" because of their traditional uses as medicine (scurvygrass!) or food (marshmallow!). Or indeed, ink (da Vinci!)

Of course, the Common Cuttlefish has no intention of being useful to monks, photographers or anyone else with circular pupils. It just wanted to get away. Alas, deep within the flesh of every cuttlefish is something else that has its uses...

Image: BioImages - the Virtual Fieldguide (UK)
It's called the cuttlebone. It's like a small, internal shell made of aragonite and it's riddled with gas-filled chambers to help with buoyancy. This stuff be can used to make moulds for jewellery and was once powered and added to toothpaste. Now it's most common as a dietary supplement for pet birds, reptiles and snails who need a calcium boost. Perhaps it's a good thing we humans got that mutation that lets us drink milk as adults.

It's all rather macabre for the cuttlefish. I'm sure they write all sorts of existential poetry about the value of their own bodies. When they're not killing, that is.

Like all other cephalopods, cuttlefish are voracious predators. They make use of expert camouflage skills, changing their skin colour and texture to match their surroundings, before pouncing on hapless fish and crustacean.

Image: WoRMS for SMEBD
8 arms, 2 tentacles
Like squid, cuttlefish have 8 relatively short arms and 2 long tentacles. Unlike squid, you almost never see the tentacles! They're typically hidden away in pouches when not in use, and they're mainly used on the hunt.

Cuttlefish have two different ways of getting a grip on prey. One is to simply smother them with their arms. It looks like this is used on crabs and lobsters who would just love to fight back with their claws. Such quarry must be quickly manipulated and tightly held to prevent any nasty nips.

Video: AnimalsFight
Check out the tentacles at 1:10

The other method finally involves those secret tentacles. The cuttlefish dons camouflage colours and slowly swims toward its target with its undulating fins. It appears as nothing more than a stone or a heap of sand, mere scenery of the sea. Then, without warning and with shocking speed, a pair of tentacles shoot out, grab hold of prey and bring it toward the mouth.

The cuttlefish can now eat at leisure, using their tough beak to crack, rip and tear, W-eyes smiling all the while.

Cuttlefish don't do all this for the sheer pleasure of killing. They're not dolphins, after all. They need all the food they can get to grow and do the things adults do.

Common Cuttlefish spend most of their time at depths of up to 200 metres (650 ft), but they migrate to shallower waters in the breeding season. Then the males have to get to work attracting a female with bright, rapid colour changes to show how pleased he is to see her. Then he might have to physically fight other males. It's exhausting!

Image: Eric Burgers
Inky eggs
Finally, hopefully, he will be allowed to pass her a spermatophore to fertilize her eggs. She lays somewhere between 100 and 1,000 eggs, each one packed with that famous sepia ink to provide camouflage, and all attached to sea weed, rocks or shells.

And with that, both male and female die.

The eggs meanwhile hatch after one to three months, and tiny cuttlefish just 5 cm (2 in) long immediately start lunging at tiny prey. They need all the food they can get; they'll be mature in just 18 months, ready to have children of their own and then die. So it is when you have a paltry lifespan of two years.

Common Cuttlefish live fast and die young. We'll have to wait until their collected works are published before we see how they feel about leaving quite so useful a corpse.


Lear's Fool said...

I LOVE cuttlefish!

I had a friend who called them 'cuddlefish' because she thought they were cute. Then she saw that video where one nommed an octopus playing with a wrench.

Now she likes them a little less. I still think they're cool

Joseph JG said...

I saw that video just recently! It's quite scary. It's incredible how many horror movies are going on in the world if only there were cameras to film them.

TexWisGirl said...

rather cute but definitely odd. cuddlefish - i like that. :)

Joseph JG said...

Yup! I guess they're cuddly but also fishy. :P

Lear's Fool said...

With all those arms, they ARE kind of made of hug!

And yeah, nature makes me embarrassed for our horror movies.

We need somebody like you as a consultant on every monster movie script, so you can say 'you think THAT'S freaky?' and point out twenty freakier things so they have to top it.

Esther said...

I'm surprised it took you this long to get to them, haha! One of the loveliest creatures in the deep blue sea.

ElBandito said...

Woot! Cuttlefish! Those guys are my faves of all the animal kingdoms!

And woah, thanks for the in depth article! I didn't know the Common Sepias can get that big, not to mention how sadly short their lifespans are. But at least I've walked away realizing how much more we're finding out on these mysterious species.

Finally, can I say how grateful I am that you've dug out some interesting and indepth videos? I can't imagine how hard those are to come by on the 'net, so it's awesome to see so much proof on their behaviors.

Joseph JG said...

@Lear's Fool: A whole new career beckons! I can just sit back and demand people make me say "wow".

@Esther: There are quite a few rather obvious ones I haven't gotten to yet. Some of them I've been meaning to do for a couple years now!

@ElBandito: Alas, it's common - even the general rule - for cephalopods to die right after they mate for their first and only time.

I'm glad you appreciate the videos! I was pleased to find one with those tentacles in action. It's not something you see very often!

Unknown said...

Those tentacles where awesome. I didn't know they could do that and it looked really cool. I like how they clearly focus when hunting.

Joseph JG said...

Yeh, it's amazing how they stare at their prey, stalk and prepare their attack. It looks so intelligent it's a little scary!

Anonymous said...

are they made out of teddybears?

Anonymous said...

No but they should be.

Anonymous said...

Anonymous said...

I request for them to make them out of teddy bears instead please do it guy that invented cuddlefish