BREAKING NEWS: Sleeper sharks as predators of giant squid

[Phil]

Very interesting report from the BBC detailing the discovery of Architeuthis and Mesonychoteuthis remains inside sleeper sharks in Antarctic waters.

http://news.bbc.co.uk/1/hi/sci/tech/3370019.stm

 

[joel_ang]

Fascinating!!!

I do wonder why there are No battlescars on the sharks. Maybe dead or dying archi's which haven't come to the surface.

Any Idea...Anyone?

 

[Phil]

Indeed Joel, that's a good point. Obviousdly I have no idea, but perhaps the sleeper attacks the squid from the rear, avoiding the arms. Unless of course the sleeper is just scavenging corpses. Mind you, that would imply the shark inhabits a benthic environment at the sea bed, I've no idea if this accurate or not.

I'm going to have to look up sleeper sharks, this is all very interesting.

 

[Steve O'Shea]

What a buzz!! The 'Colossal Squid' is now recognised as bigger and meaner than the 'Giant Squid' in popular press!! (even if the length of the giant squid depicted in the illustration is cited as 18m, and in text 12m).

I do like the statement that the sharks are taking larger squid (on average) than the sperm whale ....... it means that the beaks we have from whale stomachs might not be the largest beaks known (that the animal could get larger than we know ....)

.... I'll write to Yves (he's a squid beak guru; we're hoping he'll be here this year) and enquire about the citation 'Giant Squid' in Antarctic waters. Architeuthis isn't supposed to move into Antarctic waters (this could be a press booboo). Of course the blue shark is also known to take the adult Architeuthis (and I believe maybe another shark species also), but that doesn't matter - I think they're talking Mesonychoteuthis more than anything.

Cool!

 

[Colin]

yes glad to see ole messie mentioned too.... em, and the london bus scale again lol

 

[um...]

The actual article cites a maximum LRL of 38.8mm (mean 22.3mm) for M. hamiltoni beaks found in the sharks' stomachs. Estimated ML for the owner of that beak is 2.37 m (apparently). Based on some of the pictures of the Sepioteuthis juvies, I wouldn't be surprised to see that Messie eating the shark.



Cherel, Y. & Duhamel, G. Antarctic jaws: cephalopod prey of sharks in Kerguelen waters. Deep-Sea Research I 51, 17-31 (2004).

 

[Fujisawas Sake]

Good point, um..., and that was my question as well. Now, Pacific sleeper sharks have been known to grow to immense size (great white size and above), but an active predator of the Messie? That sounds interesting... I mean, wouldn't a massie put up a hell of a fight?

Oh, and Steve.. Do you still think the messie is an active hunter or ambush pred like archi?

Oh, and if these are scavenged, does that mean that they may be eating the casualties left ovr after mating and egg-laying, like the Loligo die off we see off the coast in CA after mating?

Sushi and Sake,

John

 

[Fujisawas Sake]

Whoa whoa whoa.... "Rely" on squid? The Pacific sleeper eats sunken whale carcasses, dead fish, and a lot of other stuff apparently... Is this a completely different species?

John

 

[um...]

The sharks had a bunch of other stuff in 'em:

Stomach contents regularly contained whole specimens of Patagonian toothfish, and discarded fish heads of that species (fishery waste), which were most likely eaten directly in trawls and scavenged at the bottom, respectively. Other prey items were demersal fishes (mainly the skates Bathyraja irrasa and B. eatonii, and the nototheniids Notothenia rossii and Lepidonotothen squamifrons), benthic invertebrates (e.g. sea stars, ophiurids) and carrion. The stomach of nine sharks contained big chunks of flesh (up to 30 kg), which, in 2 cases, were identified as belonging to fur seals (probably the Antarctic fur seal Arctocephalus gazella).

I don't recall any mention of the estimated proportion of cephalopod on the menu (by weight).

 

[mikeconstable]

Sleeper Sharks

The Greenland sleeper shark is a sluggish creature which dines on active fish like char! How??
Many puzzles still to be sorted out.
Sleepers are known to be persistant feeders on waste animal material, and difficult to drive off.

 

[joel_ang]

I saw a docu on animal planet showing sleeper sharks along with hagfish and others feeding on a sunken grey whale carcass. The fish really looked slow and senile,maybe a few of the sharks ate a giant squid carcass and was caught before all of it was digested?

 

[Phil]

Hmm...this may be a stupid question but if Architeuthis body tissues are saturated with ammonia keeping the animal buoyant, following death would one expect the carcass to rise to the surface, remain floating at depth with a neutral buoyancy before breaking up, or sink to the bottom? Without propulsive power from the fins would the dead animal rise like a cork in a bottle or do the ammonia ions keep it perfectly in balance, as I suspect?

If the sleeper sharks are feeding off corpses, I wonder if the scenario is that they are feeding off drifting bodies or scavenging on the sea bed.

 

[MuscaDomestica]

Don't the sleeper sharks also have a copepod that lives in one of their eyes, effectively making them blind?

 

[Fujisawas Sake]

Musca,

I don't think that's a rule, rather that some have been found with parasitic infections. Where'd you hear that? I would like to read the report, mostly because I do take an interest in parasites.

John

 

[Clem]

Wow, this is all very weird.

I'd like most to know how far along in the digestive process the squids had advanced before the sleepers were captured, and how long (approx) the sharks had been in the nets before being examined. One possibility is that the sharks find themselves in the nets with the squid and consume them before expiring; that's why I'd be keen to know what condition the squid were in.

Though the sleepers appear quite placid, they are very powerful animals, and well equipped with the sensory panoply that makes sharks such effective hunters. And, despite their huge eyes, even Colossals have blind spots.



Clem