SPAIN (17 Oct 2006) -- Beaked whales have astonished animal researchers by smashing the record for the deepest dive by an air-breathing animal. Zoologists studying Cuvier's beaked whale recorded specimens diving 6,230ft (1,899m) under the surface, easily beating the record of 4,000ft held by the sperm whale. The beaked whale was able to hold its breath for 85 minutes while it completed the epic dive. The scientists studying the marine creature were able to record echolocation clicks that bounced off smaller animals during the dive, suggesting that the whale was hunting. "The dives near 1,900m constitute the deepest confirmed dives reported from any air-breathing animal," scientists from Woods Hole Oceanographic Institution, in the United States, said. "This extreme deep-diving behaviour is of particular interest since beaked whales stranded during naval sonar exercises have been reported to have symptoms of decompression sickness." The team studied Cuvier's beaked whales (Ziphius cavirostris) and Blainville's beaked whales (Mesoplodon densirostris) off Spain and Italy using tags to record the movements. Peter Tyack, of the institution, said that there were behavioural similarities with the much better-studied sperm whales and elephant seals, but also some significant differences. "These two beaked whale species make long, very deep dives to find food, and then make shallow dives and rest near the surface," he said. "By contrast, sperm whales and elephant seals can make a series of deep dives without the need for prolonged intervals between deep dives. We think that beaked whales return to the surface after deep dives with an oxygen debt and need to recover before their next deep dive." | | The world record for the deepest dive by air-breathing animals (human and non-human) in the unassisted category (no weights, no bags, no sleds, no nose-plugs, no goggles) has been smashed. The epic dive to a depth of 1,899m on one breath of air lasted 85 minutes. The study, reported in The Journal of Experimental Biology, suggests that it is not deep dives that leave the whales at risk of decompression sickness but repeated dives to shallower depths of 100-250ft. The team reported: "Deeper parts of the dive do not increase the risk of decompression problems. However, if beaked whales responded to sonars with repeated dives to near 50m, this could pose a risk." The Blainville's beaked whales dived to a maximum depth of 1,250m and 57 minutes in duration. Dr Tyack added: "No matter what the precise cause of the strandings is, we need to develop effective mitigation strategies to reduce the accidental exposure of beaked whales to bay sonar. "The information in this study provides critical data to design efficient acoustic and visual detection methods for these at-risk species of marine mammals." SOURCE - Times Online |
