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Blainvilles Beaked Whale - Mesoplodon densirostris
Topic Started: Jan 9 2012, 12:24 PM (2,340 Views)
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Blainville's Beaked Whale - Mesoplodon densirostris

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Ziphiidae
Genus: Mesoplodon
Species: Mesoplodon densirostris

Blainville's Beaked Whale (Mesoplodon densirostris), or the Dense-beaked Whale, is the widest ranging mesoplodont whale and perhaps the most documented. Henri de Blainville first described the species in 1817 from a small piece of jaw—the heaviest bone he had ever come across—which resulted in the name densirostris (Latin for "dense beak"). Off the northeastern Bahamas, the animals are particularly well documented, and a photo identification project started sometime after 2002.

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Physical description
The body of Blainville's Beaked Whale is robust, but also somewhat compressed laterally compared with other Mesoplodonts. The males have a highly distinctive appearance, the jaws overarch the rostrum, like a handful of other species, but does it towards the beginning of the mandible and then sloped down into a moderately long beak. Before the jaw sloped down, a forewords facing, barnacle infested tooth is present. One of the more remarkable features of the whale is the extremely dense bones in the rostrum, which have a higher density and mechanical stiffness than any other bone yet measured. At present, the function of these bones is unknown, as the surrounding fat and the brittleness of the bone make it unlikely to be used for fighting. It has been suggested that it may play a role in echolocation or as ballast, but without sufficient behavioral observation, this cannot be confirmed. The melon of the whale is flat and hardly noticeable. Coloration is dark blue/gray on top and lighter gray on the bottom, and the head is normally brownish. Males have scars and cookie cutter shark bites typical of the genus. Males reach at least 4.4 meters (14 ft 6 in) and 800 kg (1800 pounds), whereas females reach at least 4.6 meters (15') and 1 tonne (2200 pounds). Juveniles are 1.9 meters long (6 ft 4 in) when born and weigh 60 kg (130 lb).

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Population and distribution
This species of beaked whale is found in tropical and warm waters in all oceans, and has been known to range into very high latitudes. Strandings have occurred off Nova Scotia, Iceland, the British Isles, Japan, Rio Grande do Sul, South Africa, central Chile, Tasmania, and New Zealand. The most common observations take place off Hawaii, the Society Islands, and the Bahamas. The species does not migrate. It inhabits water 1600 to 3000 feet deep. Despite the relatively common nature of the whale, no population estimates are available.

The whales are seen in groups of 3-7 individuals. Dives have been measured out to at least 22 minutes. When the cetacean surfaces, it does so slowly and with little splashing. It probably feeds mainly on squid as the stomach of one stranded individual contained only squid.

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The beaked whale has occasionally been hunted, but has never been a specific target.
Edited by Taipan, Oct 12 2017, 02:34 PM.
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Identifying Beaked Whale Foraging Habitat in the Bahamas

ScienceDaily (Apr. 27, 2011) — In a recent study to be published on April 27, 2011, in the peer-reviewed open-access journal PLoS ONE, Dr. Elliott Hazen and colleagues found that oceanographic and prey measurements can be used to identify beaked whale foraging habitat. The research team from Duke University, Woods Hole, and the Naval Undersea Warfare Center listened for foraging beaked whales and measured ocean features and distributions of prey off the east coast of Andross Island in the Bahamas.

Their manuscript provides evidence that these difficult to study deep-diving creatures use specific ocean features such as salinity and temperature to find their prey. This is the first study describing their distribution and feeding habitat relative to ocean features Blaineville's beaked whales regularly dive over 1000 meters for over an hour in search of prey which varies from 400-1000 meters. The shy and elusive toothed whales feed primarily on fish and squid in the ocean's deep scattering layer, an important prey resource for many species throughout the world's oceans. In addition, Blaineville's beaked whales are listed as data deficient by the IUCN, and very little is currently known about the ecology of these creatures.

Beaked whale species are thought to be sensitive to noise arising from certain human activities; in 2000, beaked whale strandings were observed coinciding with naval sonar exercises in the Bahamas. Understanding the distribution and behavior of these species is important to minimize harmful impacts from human uses of the ocean. Researchers worked aboard the R/V Revelle, an 86-meter vessel out of Scripps Institute of Marine Science. Fisheries acoustics data found scattering layers of prey on the western edge of the tongue of the ocean were denser than those at the eastern edge. Eighty-two bottom-mounted hydrophones also recorded increased foraging activity on the western edge of the basin.

The hydrophone range at AUTEC allowed for unprecedented measurements of the habitat and behavior of these elusive predators providing "necessary insight into how beaked whales interact with their environment." Studies on harbor porpoises and bottlenose dolphins have shown how modeling habitat can be a powerful tool to inform spatially adaptive management of pelagic predators (Bailey and Thompson 2009, Embling et al. 2009). Further work is necessary to determine whether this foraging model could be extrapolated to other seasons or populations.

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The Tongue of the Ocean and study site off the eastern coast of Andross Island, in the Bahamas.


Journal Reference:

Elliott L. Hazen, Douglas P. Nowacek, Louis St. Laurent, Patrick N. Halpin, David J. Moretti. The Relationship among Oceanography, Prey Fields, and Beaked Whale Foraging Habitat in the Tongue of the Ocean. PLoS ONE, 2011; 6 (4): e19269 DOI: [url]10.1371/journal.pone.0019269 [/url]

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Do Whales Get the Bends?
Scientists take a deeper look at decompression sickness in marine mammals.

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The jaw fat of beaked whales like this one—a dense beaked whale (Mesoplodon densirostris) in Kona, Hawaii—is especially good at dissolving nitrogen gas, according to a new study.

By Rachel A. Becker, National Geographic

Whales may be able to get the same decompression sickness that scuba divers do when they surface too quickly from a dive, despite their adaptations to a life in the ocean.

The painful and potentially life-threatening condition known as decompression sickness, or the bends, occurs when gasses bubble out of solution in the body, forming air pockets in divers’ blood and organs as they rise. But scientists have had trouble studying this phenomenon in non-human divers because little is known about what happens to these gasses in non-human tissues.

Researchers from the University of North Carolina Wilmington investigated how marine mammals’ tissues—specifically, fat deposits in the jaws of toothed whales that are used in echolocation—absorb nitrogen gas, one of the gases that contributes to the bends. They found that the makeup of the fat affected how much nitrogen gas dissolves in it—and that different species had different fat compositions.

In combination with data on how often and how deep these marine mammals dive, the researchers could estimate whale species' risk for decompression sickness. They published their results Wednesday in the Journal of Experimental Biology.

Why It Matters

Once, scientists thought that diving sea creatures like the elusive, deep-diving Cuvier’s beaked whale were resistant to the bends, but mounting evidence suggests that this may not be entirely true.

In 2002, international navy sonar exercises were linked to a mass stranding of 14 whales in the Canary islands. The whales had gas bubbles in their tissues, a sign of decompression sickness.

“If, for example, sonar is affecting these animals so they get decompression sickness, what can we do to prevent that?” says Andreas Fahlman, a biology professor at Texas A&M University at Galveston who studies the physiology of deep diving animals. Fahlman was not involved in this research.

The Big Picture

To figure out how a sonar blast that startles a whale out of its normal diving behavior might pose a threat to its health, scientists need data on how much nitrogen gas whale tissues can absorb.

But that didn't exist until now; researchers were using data collected in olive oil and bone marrow from oxen and sheep—not marine mammals.

That’s why Gina Lonati, a graduate student at the University of North Carolina Wilmington, began collecting the heads of whales and other marine mammals, and extracting their fat.

“In order to see if these animals may be susceptible to something like the bends or decompression sickness, we want to see how much nitrogen their fats can hold,” she says. “Because the more they can hold, it’s possible the more it may affect them when they surface.”

What's Next

Lonati says that her successor on this project is looking into the potential for gas exchange in the vasculature of an even bigger range of species. She hopes that her research will be used to revise the existing models of how diving marine mammals manage nitrogen gas when they dive.

Fahlman thinks that Lonati's results could also allow modelers to estimate how boats, or even climate change, might affect marine creatures like whales.

“It may seem like a very simple and detailed thing they’ve done, but the work that these people put into this, the difficulty to get these measurements—its absolutely phenomenal, he says. “Little by little we start to understand these animals more.”


Nitrogen solubility in odontocete blubber and mandibular fats in relation to lipid composition

Gina L. Lonati, Andrew J. Westgate, D. Ann Pabst and Heather N. Koopman
doi: 10.1242/​jeb.122606
August 2015
J Exp Biol 218, 2620-2630.

Understanding toothed whale (odontocete) diving gas dynamics is important given the recent atypical mass strandings of odontocetes (particularly beaked whales) associated with mid-frequency naval sonar. Some stranded whales have exhibited gas emboli (pathologies resembling decompression sickness) in their specialized intramandibular and extramandibular fat bodies used for echolocation and hearing. These tissues have phylogenetically unique, endogenous lipid profiles with poorly understood biochemical properties. Current diving gas dynamics models assume an Ostwald nitrogen (N2) solubility of 0.07 ml N2 ml−1 oil in odontocete fats, although solubility in blubber from many odontocetes exceeds this value. The present study examined N2 solubility in the blubber and mandibular fats of seven species across five families, relating it to lipid composition. Across all species, N2 solubility increased with wax ester content and was generally higher in mandibular fats (0.083±0.002 ml N2 ml−1 oil) than in blubber (0.069±0.007 ml N2 ml−1 oil). This effect was more pronounced in mandibular fats with higher concentrations of shorter, branched fatty acids/alcohols. Mandibular fats of short-finned pilot whales, Atlantic spotted dolphins and Mesoplodon beaked whales had the highest N2 solubility values (0.097±0.005, 0.081±0.007 and 0.080±0.003 ml N2 ml−1 oil, respectively). Pilot and beaked whales may experience high N2 loads during their relatively deeper dives, although more information is needed about in vivo blood circulation to mandibular fats. Future diving models should incorporate empirically measured N2 solubility of odontocete mandibular fats to better understand N2 dynamics and potential pathologies from gas/fat embolism.

Edited by Taipan, Oct 12 2017, 02:32 PM.
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Two beaked whale species take very long, deep dives for their size

October 11, 2017

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Beaked whale. Credit: Bahamas Marine Mammal Research Organization

Two relatively small beaked whale species took exceptionally long, deep dives while foraging in the Bahamas, confounding expectations that larger whales dive should be able to dive for longer than smaller whales, according to a study published October 11, 2017 in the open-access journal PLOS ONE by Trevor Joyce from Scripps Institution of Oceanography, United States of America, and colleagues.
Most species of Ondotocetes (toothed whales and dolphins) eat creatures found at depths from tens to thousands of meters, and beaked whales dive as deep as 2,992 meters for their prey. Dive capacity in Ondontocetes generally increases with body mass, presumably because bigger bodies have more substantial oxygen reservoirs. However, another hypothesis holds that beaked whales—a type of toothed whale—extend the duration of deep dives by shifting from aerobic to anaerobic respiration.
To examine these competing hypotheses, Joyce and colleagues used satellite telemetry and biologging to study dive patterns of five toothed whale species foraging in underwater canyons in the Bahamas. The researchers tagged 17 beaked whales (12 Mesoplodon densirostris and 5 Ziphius cavirostris) as well as 13 melon-headed whales (Peponocephala electra), 15 short-finned pilot whales (Globicephala macrorhynchus), and 27 sperm whales (Physeter macrocephalus). Data included body weights, concentrations of myoglobin (a muscle protein that binds oxygen), and intervals between deep dives.
The researchers found that the two beaked whale species took very long, deep dives for their size. They also took exceptionally long recovery periods between deep dives. These inter-deep-dive intervals averaged 62 minutes for M. densirostris and 68 minutes for Z. cavirostris.
When taken together, body size and myoglobin concentration explained only 36% of the variance in maximum dive times. However, when inter-deep-dive intervals are also considered 92% of the variance in maximum dive times is explained. Longer inter-deep-dive intervals likely correspond with metabolism of the lactic acid that accumulates during anaerobic respiration, supporting the hypothesis that beaked whales extend their foraging dives by shifting from aerobic to anaerobic respiration.
The researchers suggest that this alternative strategy allows the beaked whales to access deeper prey without growing larger, which fits with the fact that prey is limited at the extreme depths, of up to 1,900 meters, where they forage.


Journal Reference
Joyce TW, Durban JW, Claridge DE, Dunn CA, Fearnbach H, Parsons KM, et al. (2017) Physiological, morphological, and ecological tradeoffs influence vertical habitat use of deep-diving toothed-whales in the Bahamas. PLoS ONE 12(10): e0185113 doi.org/10.1371/journal.pone.0185113

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Table 1. Number of satellite tag deployments between 2009–2014, by tag type and sex.
Tagging events indicate the number of separate encounters with groups of odontocetes during which tagging took place; some groups may have been repeatedly encountered across multiple years. Also shown are the total hours of dive data recovered for each species in the behavior and time series logs of SPLASH tags, time-at-temperature histograms of SPOT tags, and mean duration of tag transmission for five species of deep-diving odontocetes in the northern Bahamas.

Dive capacity among toothed whales (suborder: Odontoceti) has been shown to generally increase with body mass in a relationship closely linked to the allometric scaling of metabolic rates. However, two odontocete species tagged in this study, the Blainville’s beaked whale Mesoplodon densirostris and the Cuvier’s beaked whale Ziphius cavirostris, confounded expectations of a simple allometric relationship, with exceptionally long (mean: 46.1 min & 65.4 min) and deep dives (mean: 1129 m & 1179 m), and comparatively small body masses (med.: 842.9 kg & 1556.7 kg). These two species also exhibited exceptionally long recovery periods between successive deep dives, or inter-deep-dive intervals (M. densirostris: med. 62 min; Z. cavirostris: med. 68 min). We examined competing hypotheses to explain observed patterns of vertical habitat use based on body mass, oxygen binding protein concentrations, and inter-deep-dive intervals in an assemblage of five sympatric toothed whales species in the Bahamas. Hypotheses were evaluated using dive data from satellite tags attached to the two beaked whales (M. densirostris, n = 12; Z. cavirostris, n = 7), as well as melon-headed whales Peponocephala electra (n = 13), short-finned pilot whales Globicephala macrorhynchus (n = 15), and sperm whales Physeter macrocephalus (n = 27). Body mass and myoglobin concentration together explained only 36% of the variance in maximum dive durations. The inclusion of inter-deep-dive intervals, substantially improved model fits (R2 = 0.92). This finding supported a hypothesis that beaked whales extend foraging dives by exceeding aerobic dive limits, with the extension of inter-deep-dive intervals corresponding to metabolism of accumulated lactic acid. This inference points to intriguing tradeoffs between body size, access to prey in different depth strata, and time allocation within dive cycles. These tradeoffs and resulting differences in habitat use have important implications for spatial distribution patterns, and relative vulnerabilities to anthropogenic impacts.

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