Monday, June 29, 2009
Octopus and squid can hear.
The discovery resolves a century-long debate over whether cephalopods, the group of sea creatures that includes octopus, squid, cuttlefish and nautiluses, can hear sounds underwater. Compared to fish, octopus and squid do not appear to hear particularly well. But the fact they can hear raises the possibility that these intelligent animals may use sound to catch prey, communicate with one another or listen out for predators.
The question of whether cephalopods can perceive sound has been controversial since the early 20th Century. Some experiments suggested that blind octopus seemed able to locate the sounds produced by boats or by tapping on the outside of a tank. But most cephalopods lack a gas-filled chamber, such as the swim bladders that fish can use to hear. That suggested they could not detect the pressure wave component of sound.
However, sensory physiologist Hong Young Yan of the Taiwan National Academy of Science in Taipei, Taiwan suspected that octopus and squid might use another organ called the statocyst to register sound. The statocyst is a sac-like structure containing a mineralised mass and sensitive hairs. Fish also use it to detect sounds, and in previous research, Yan showed that prawns can use their statocysts to hear. "So we extended our work from prawns to cephalopods," says Yan.
Yan's team tested the auditory capabilities of two species, the Common octopus Octopus vulgaris and the squid Sepioteuthis lessoniana, often called the Bigfin reef squid. They discovered that the octopus can hear sounds between 400Hz and 1000Hz. The squid can hear an wider range of sound from 400Hz to 1500Hz, they report in Comparative Biochemistry and Physiology, Part A. "That indicates that squid have a better hearing capability than the octopus," says Yan. "Interestingly though, both species hear best at a frequency of 600Hz."
Yan's team had to overcome particular technical challenges to investigate the cephalopods' hearing ability. The usual way to prove that an organism can hear is to measure how its nervous system electrically responds to sound. But that can involve directly attaching electrodes to exposed nerves, an invasive procedure that could harm delicate cephalopods. So Yan invented a non-invasive method, which involves placing electrodes on an animal's body to measure the electrical activity in its brain. In this way, he could measure within just a couple of hours whether the brain of an octopus or squid responds to sound.
The discovery could open up a new understanding of cephalopod behaviour. "The key question which I would like to investigate is what kind of sounds are they listening to?" says Yan. "Perhaps they listen to sound to evade predators and can eavesdrop to sounds made by their prey. Or, perhaps they even could make sounds to communicate among themselves."
See the rest of the article here.
Friday, June 26, 2009
Ms. Dina is a young Greek heiress raised to the highest standards, although she refuses to behave as a proper lady. She can instead be found exploring the deep caves and crevices under the sea that watched her being born. Find her here.
Friday, June 19, 2009
Thursday, June 18, 2009
VelvetMechanism on Etsy recently pointed out to me these charming octopus legos. She uses them to create awesome 'geek chic' necklaces. But if you're just wanting to build something with some cool legos, swing by Ebay, where a quick search proved that they come in Glow in the dark varieties as well as black and red.
Because no lego set is complete without a cephalopod!
Wednesday, June 10, 2009
Monday, June 8, 2009
Marine experts have given 25 octopuses a Rubik's Cube each in a study aimed at easing their stress levels in captivity.
Scientists believe the intelligent sea creatures have a preferred arm out of eight that they use to feed and investigate with. They are now testing this theory with a month-long observation project in which the octopuses will be given food and toys to play with. They will then record whether the creatures use a specific limb to pick up the object or if they are octidextrous. It is hoped the results of the Sea Life Centre study will shed light on 'handiness' in the animal kingdom.
Claire Little, marine expert at the Sea Life Centre in Weymouth, Dorset, said the study could eventually help to reduce stress among octopuses. She said: "It will be very interesting to see the results. Uniquely, octopuses have more than half their nerves in their arms and have even been shown to partially think with their arms. We hope the study will help the overall well-being of octopuses. They are very susceptible to stress so if they do have a favourite side to be fed on, it could reduce risk to them."
The octopus research will take place in the 23 branches of the Sea Life Centre attractions Britain and Europe. [...] The results will be analysed by Sea Life Centre biologists and the results will be announced in the autumn.Full article here.
Though she lives and bakes in Seattle, WA, she does have a shop on Etsy - so pop in and give her some yummy loves. Note: if you click on the items in her shop, you'll see pics of different cakes. Personally, I think she should also list her wonderful cookies and other pastries that would be more readily available to ship priority, but one step at a time.
Saturday, June 6, 2009
"It's about as unlikely as capturing a "fossil sneeze," but researchers have found the second known set of octopus fossils, a new study says. "
Because its all soft body and no bones, its incredibly rare for cephalopods to leave fossil evidence of their passing, photo and article are definitely worth a look.
Photo © National Geographic