Sperm Whales And Giant Squid

[glen]

Hi everyone,



There is an interesting article at the National Geographic website about the diving habits of giant squid and sperm whales. Here is a snippet of the results:

During the day the [sperm] whales and [giant] squid spent about 75 percent of their time at depths ranging from 600 to 1,300 feet (180 to 400 meters).



At night, the tagged squid spent at least half of their time above 600 feet (180 meters), most likely following small fish and other prey that migrate toward the surface at night and then return to deeper waters during the day.



Unlike the squid, however, the sperm whales only slightly altered their diving pattern at night, continuing to spend most of their time at lower depths.

Here is another interesting quote relating to the amount of squid eaten by sperm whales:

The animals have a voracious appetite for squid. Researchers estimate that more than 110 million tons (100 million metric tons) of squid - equivalent to the entire annual harvest of all the commercial fisheries on Earth - may be consumed by sperm whales every year.

Here is a link to the full article:



[url="http://news.nationalgeographic.com/news/2007/03/070312-giant-squid.html"]http://news.nationalgeographic.com/news/20...iant-squid.html[/url]

[scissorhands]

Interesting article Glen, thanks for posting these articles.... 3 more squid tonight, starting to get the hang of it. <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='' /> How do they see at those depths? I'm wondering if they have more senses going for them in those huge heads with big eyes?



Frank

[glen]

i guess maybe they can use sonar to help them find the tasty giant squid! <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' />

[scissorhands]

the squid must hunt in the dark too? no light below 500meters

[glen]

beats me! maybe they have a sixth sense <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' /> or maybe they eat fish that glow in the dark <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' />

[Student]

I don't have full access to the article, but I found an abstract that seems to explain it:



[url="http://www3.interscience.wiley.com/journal/119926990/abstract?CRETRY=1&SRETRY=0"]http://www3.interscience.wiley.com/journal...=1&SRETRY=0[/url]



[url="http://www3.interscience.wiley.com/journal/118534279/home"]Marine Mammal Science[/url]

[url="http://www3.interscience.wiley.com/journal/119926968/issue"]Volume 18 Issue 1[/url], Pages 42 - 54

HOW DO SPERM WHALES CATCH SQUIDS?Kurt M. Fristrup [sup][/sup] G. Richard Harbison [sup][/sup] [url=http://][/url][sup][/sup]

"Vision may play a central role in sperm whale predation. Two complementary hypotheses regarding the detection and capture of prey items are presented, based on a review of mesopelagic ecology. The first hypothesis postulates that sperm whales locate their prey visually, either silhouetted against the midwater "sky," or by searching for bioluminescence produced by the movements of their prey. The second hypothesis postulates that sperm whales create a zone of stimulated bioluminescence around the mouth, which attracts squids and other visual predators. Studies of midwater fishes and invertebrates document the importance of vision in mesopelagic communities. If sperm whales search for silhouetted prey, they should be oriented upside-down to improve visual coverage and to facilitate the transition from search to prey capture. Prey capture events should be marked by excursions toward the surface. If they lure their prey, they should swim at a steady pace, with little rapid acceleration, and spend most of their time foraging at depths with the greatest potential for stimulated bioluminescence."



I hope that helps!

[glen]

hi, thanks for sharing the info! looks like even the scientists have no idea so i feel a bit better <img src='http://www.squidfish.net/forums/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='' />