Deep-sea giant squid (Architeuthis) remain one of the ocean’s most charismatic zoological mysteries. While there are plenty of specimens in museums around the world, little is known about their behaviour. Only recently have fleeting glimpses been captured of these creatures in their natural habitat; a 2005 paper (http://rspb.royalsocietypublishing.org/content/272/1581/2583.full) in Proceedings of the Royal Society B described the first ever wild observations of a live giant squid. The author’s photographs showed a huge squid actively hunting at 900m below the surface and they even managed to recover a tentacle that snagged on the bait line (see panels ‘e’ and ‘f’ in the figure).
We also know about the predator-prey interaction between sperm whales and giant squid from the sharp-sucker scars often seen on whale skin and stomach contents (squid beaks are indigestible making them a useful clue to the diet of sperm whales).
Earlier this year, footage taken by a manned submersible was broadcast showing a giant squid 1000m deep in the North Pacific. The footage was captured using near-infrared light (using invisible to humans and squid) since giant squid avoid the bright white light used in conventional filming- perhaps something to do with those enormous eyes? (have a look here: http://www.eeb.yale.edu/ugrad/eeb171pdfs/sa-246-1982.pdf)
See clips from the video at http://www.youtube.com/watch?v=1KN5N1QDaRQ
(picture credit: NHK/NEP/Discovery Channel via Reuters)
As an aside, it’s worth taking a look at this report on the unusual mating behaviour of giant squid – it turns out that male squid giant inject spermatophores directly into wounds that they form on the tentacles of a female:
More recently a somewhat alarming article showed how male squid overcome the challenges of mating at great depths using a ‘super squid sex organ’ – see the long white tubular structure in the picture below.
Bit of a tricky one this…..
Make no bones about it
While I’m sure you’ve all seen the spectacular beaching behaviour of predatory killer whales, Orcinus, and dolphins, Tursiops, here’s a report of similar behaviour from a fish a little closer to home. It seems that catfish, Siluris glanis, have recently learnt to snatch and eat pigeons from the riverbank.
The proof of the matter is shown in this picture:
You can see unsuspecting pigeons resting on the riverbank and predatory catfish lurking nearby. Looking closely at the smaller images reveals a successful bird catch.
Interestingly catfish do not display this behaviour in their natural range and so it may represent a fascinating adaptation to the new environment. Perhaps there are not enough fish to eat in these rivers or maybe catfish have simply developed a taste for pigeon? Either way, behavioural adaptation in this species may have implications for the ecological functioning of this riparian environment.
The paper is available in PLoS ONE:
Any ideas on the identity of this fine bird?
What is this animal and what does it have in common with geckos?
The male club-winged manakin (Machaeropterus deliciousus), native to the Equadorian/Colombian Andes, uses wing-produced sonations to attract a mate. The secondary wing feathers of the males are grossly enlarged and are resonated by the birds (at around 36 knocks in 0.33 seconds) to produce a harmonic ‘ting’ sound.
Fancy plumage, courtship behaviours and song in male birds are often the result of sexual selection by female choice. All of which are associated with a cost to males (whether energetic or a risk of predation) and provide females with an opportunity to assess male quality before deciding who contributes to their offspring.
Interestingly, the ulnae (wing-bones to which the secondary feathers are attached) are completely solidified in these males, with volumes three times greater than those in other birds of a similar size. Altogether, this results in a massive bone, which should assist with the sound production.
The ulnae of three similar sized birds, closely related to the golden-collared manakin (left), and the golden collared-manakin (right)
A solidified (not hollow) wing bone has never before been reported in a volant bird, and is perhaps, in this case, a consequence of female choosiness for song quality.
A cost to these males may be the loss of the benefits of hollow wing bones associated with improved flight efficiency in birds, representing a trade-off between mating success and fight efficiency.
One for the comparative anatomists out there – to what animal does this skeleton belong? And how can you tell?
Photo by J. Codd.