More Friday Cephalopod news

  • Bioephemera not only shows off a chandelier to die for (if I had one installed, my wife would make sure I died for it), but has announced that she needs a cephalopodmania category. It’s infectious.

  • Another blogger with a reputation for Friday Squid blogging is Bruce Schneier. Rumor has it that he will be here at ConFusion, and the organizers are going to try and arrange an ad hoc session with the two of us, on squid.

I knew I forgot something important

I forgot to set up a Friday Cephalopod post before I left, and I don’t have my scanner with me! Don’t panic. Deep breaths. We can cope with this, by being as flexible as a cephalopod.

Here’s what I’ve done. I’ve reposted an article on Gonatus onyx, which has lovely photos of a squid and its babies. If you saw that beautiful movie of a squid releasing larvae as it was suspended in the deep, you’ll recognize it—this is one of those resonantly moving behaviors of certain species of squid: they produced huge numbers of eggs, and then just hover, completely alone and isolated in a deep layer of the ocean, brooding their young.

Also — and this will blow your mind — I will be putting up a MONDAY CEPHALOPOD!!! This is what happens when you think out of the box: you get these earthshaking, radical ideas that might change the whole nature of the blogosphere as we know it. I’m tempted to say there will be Monday, Tuesday, Wednesday, Thursday, Saturday, and Sunday Cephalopods, but no, I must step back from the abyss, and just take baby steps. One Monday Cephalopod, then we will return to the traditional Fridays, and hope the wobble induced in the Earth’s rotation will have stabilized by then.

Life of a squid

The heathen at IIDB are talking about squid—it’s infectious, I tell you, and the godless seem especially susceptible—and in particular about this interesting paper on squid fisheries. Squid are on the rise, and are impressively numerous.

We can get an idea of the abundance of squid in the world’s ocean by considering the consumption of cephalopods (mainly squid) from just one cephalopod predator the sperm whale. Sperm whales alone are estimated to consume in excess of 100 million tonnes of cephalopods a year. This is equivalent to the total world fishery catch and probably exceeds half the total biomass of mankind on the earth (Clarke 1983). It is therefore highly likely that the standing biomass of squids within the world’s oceans probably exceeds the total weight of humankind on the earth. Given such importance squid have generally not been given the attention they deserve or have not been incorporated to the degree they need to in ecosystem models. Future research needs to rectify this.

Squid are creatures of speed: they grow fast and die young. Teleosts and cephalopods follow rather different life strategies.

The form of growth of squid is also unique and interesting. Squid just keep growing. They do not show the distinctive flattening in their growth curve shown by their fish competitors. Many species growth can be modeled with exponential or linear curves. The interesting thing is they continue growing even during their maturation phase until they die or are eaten. They seem to achieve this because of a number of unique qualities, (1) they have a protein based metabolism with efficient digestion so food is converted to growth rather than stored, (2) they are efficient feeders, using their suckered arms and beak they can remove only the highly digestible parts of prey and ‘spit out the bones’ and (3) they can grow by continually increasing the number of their muscle fibres (hyperplasia) a feature not shared by their fish counterparts. While juvenile fish recruit new muscle fibres by hyperplasia they reach a point where growth only occurs by increasing the size of existing muscle fibres (hypertrophy). This probably contributes to their flattening growth curve. Alternatively, squid show both hyperplasia and hypertrophy throughout their life span, thus they continue to recruit new fibres as well as increase the size of existing fibres (Figure 1). Such a strategy might account for their continuous growth. All of the above features contribute to the unique form of growth and the ability of squid to grow fast and fill available niches. Their life is very much life-in-the-fast-lane. They are the ‘weeds’ of the sea.

Live fast, die young…and leave a really decrepit corpse, it seems. Here’s a description of a species that really knows how to have a good time.

Much of my Southern Ocean research has focused on the warty squid Moroteuthis ingens. Up until recent years this species was poorly understood and delegated to obscurity due to lack of biological information. However, this species is regularly caught in both fishing and research trawls and my research has focused on New Zealand, The Falkland Islands and more recently Australia’s sub-Antarctic island regions. The biological understanding of this species is now perhaps the best of any sub-Antarctic squid. It is a large squid growing to over 500mm in mantle length and females achieve a much larger size than males. While M. ingens is epipelagic during its juvenile stage it undergoes an ontogentic descent to take up a demersal existence (Jackson 1993). This species has a biologically unusual and interesting reproductive strategy referred to as terminal spawning (Jackson & Mladenov 1994). Although it is a muscular squid, females (and to a lesser extent males) undergo a dramatic change associated with reproduction. Females produce a huge ovary that can reach the size of a rugby ball and weigh as much as a kilogram. In fact the ovary can weigh more than the total body weight of the male. In association with the development of the ovary the female undergoes a dramatic tissue breakdown in its body wall. This process results in a total loss of muscle fibres that transforms the muscular female into something more analogous to a jellyfish and death is associated with spawning. Moroteuthis ingens and other onychoteuthids are important prey for a number of vertebrate predators (at least four mammals, 17 birds, 13 fish, Jackson et al 1998). It is suspected that this tissue breakdown may result in dead individuals floating to the surface where they are accessible to mammals and birds.

Cool stuff…read the whole paper!

Weird Tales of the Sea?

I really don’t know whether to believe this story or not. It’s a diary of a sailing trip that reports an encounter with a fellow sailor who had experienced serious difficulties.

We reported last time that Shigeo’s trip from the Galapagos to the Marquesas had been terrible — after about 1000 miles his autopilot had failed, something had gone wrong with his steering, his engine water intake had clogged temporarily, blowing his impeller, the intake for one of his heads had clogged, and, most important of all, something had slowed his speed down to 2 knots, even with full sails, a lot of wind, and the engine running. He basically drifted with the current for the last 2700 miles, taking about 8 weeks to cover a distance that his 42-foot Beneteau could easily have sailed in a fraction of that time.

i-42f25c52824f9d9e3be7eb836790ac57-squidmarks.jpg

That part doesn’t seem improbable, but the explanation for his boat’s sluggish performance is wild. Divers took a look at the hull, and found hundreds of strange circular scars all over it—they speculate that they are marks of a giant squid’s suckers.

Hmmm. I can’t believe that a giant squid would or could cling to a boat for 2 months, but I can’t think of any simple explanation for the strange marks. Any more nautically experienced people out there with a better alternative explanation? I’d be inclined to call it a hoax, but for the fact that there’s very little bang for the effort that would have had to go into it.