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Cuvier's Beaked Whale - Ziphius cavirostris
Topic Started: Jan 9 2012, 11:53 AM (2,470 Views)
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Cuvier's Beaked Whale - Ziphius cavirostris

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Ziphidae
Genus: Ziphius
Species: Ziphius cavirostris

Cuvier's beaked whale, also known as the goosebeak whale, is one of twenty named species of beaked whales. It is so rarely seen that almost everything known about this small whale has come from studying stranded animals. Cuvier's beaked whale has a tendency to strand more often than any other species of beaked whales. Stranded specimens have been noted in all oceans of the world except in both polar regions--an indication of an extremely wide distribution.

Physical Description
Cuvier's beaked whale has a robust body and a small head which is about ten percent of its body length. Its forehead slopes to a poorly defined short beak, and its mouth turns upward, giving it a goose-like profile. This whale has a depression behind the blowholes which ends in a distinct neck. Its blow is small and not very noticeable and is projected slightly forward and to the left. One of its more interesting features is that in adult males two large teeth about 2 inches long (5 cm) protrude from the tip of the lower jaw. The males use these teeth in fights with each other over females. For their part the females have smaller, more pointed teeth that remain embedded in the gums. The lower jaw of the Cuvier's beaked whale extends well beyond the upper jaw. Like other beaked whales, the Cuvier's has two deep, V-shaped throat grooves.

This whale varies greatly in color. Its back may be rusty-brown, dark gray, or fawn colored and the underside of the body may be dark brown or black. As the Cuvier's beaked whale ages, first the head and neck and then the body become more lightly colored; the heads of old males are almost completely white. The back and sides of this whale, especially the males, are often covered with double-lined scratches caused by the teeth of other males. Its sides and belly are covered with oval white patches.

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surface characteristics

Fins & Fluke
Dorsal fins of Cuvier's beaked whales may vary in shape; they may be as high as 15 inches (38 cm) and falcate (curved) or less than 10 inches (25 cm) and triangular. The fin of this whale is located well behind the mid-section. Its flukes are large and rounded at the tips and may or may not be slightly notched in the center. Its flippers are small and rounded at the tips and fold back into little depressions on the side of the body.

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Length and Weight
Maximum size is 23 feet (7 m). The average adult is 18 feet (5.5 m) and weighs 2.7 tons (2500 kg).

Squid is its primary food, though it sometimes eats fish and, rarely, crustaceans.

Matiting & Breeding
Sexual maturity is reached when the animal is an average of about 19 feet (5.8 m) long for females and 18 feet (5.5 m) for males. Calves are between 6.5 to 10 feet (2-3 m) at birth and weigh about 600 pounds (272 kg).

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range map

Distribution and Migration
Cuvier's beaked whales are found in all the oceans of the world except the polar regions of both hemispheres. They prefer deep water of over 3,300 feet (1,000 m) and avoid shallow coastal areas.

Natural History
Cuvier's beaked whales are almost never seen at sea, so we know very little about their habits. Sightings of single animals (which are probably males) have been reported, but they are more commonly seen in groups of 2 to 7. Their life span is believed to be at least 25 years.

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We know so little about this whale that there are no estimates of past or present population size. Though Cuvier's beaked whales are found stranded more often than any other species of beaked whales, only two mass strandings have been reported; one in the Galapagos and the other in Puerto Rico. These whales beach themselves singly all over the world, more often in some locations than in others. A few Cuvier's beaked whales were taken by hunters in the 1940s to 1960s in Japan's coastal whaling operations, but the numbers were so few that there was no threat to the survival of the species. This whale is not hunted at the present time. More recently, acoustical trauma has been implicated in the mass strandings of Cuvier's beaked whales in the Caribean, Azores, and the Gulf of California.


Edited by Taipan, Oct 12 2017, 01:31 PM.
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Beaked Whales Actually Hear Through Their Throats

ScienceDaily (Feb. 4, 2008) — Researchers from San Diego State University and the University of California have been using computer models to mimic the effects of underwater noise on an unusual whale species and have discovered a new pathway for sound entering the head and ears.

Advances in Finite Element Modeling (FEM), Computed tomography (CT) scanning, and computer processing have made it possible to simulate the environment and anatomy of a Cuvier's beaked whale when a sonar signal is sent out or received by the whale.

The research paper* is a catalyst for future research that could end years of speculation about the effects of underwater sound on marine mammals.

FEM is a technique borrowed from engineering used, for example, to simulate the effect of an earthquake on a building. By inputting the exact geometry and physical properties of a building the effect of forces such as an earthquake, or in this case noise vibrations, can be accurately predicted.

Dr Cranford of San Diego State University triggered the research into Cuvier's beaked whales almost ten years ago when he undertook the first ever CT scan of a large whale, which provided researchers with the very complex anatomic geometry of a sperm whale's head.

Dr Cranford said, "I think that the methods developed for this research have the potential to revolutionize our understanding of the impact of noise on marine organisms."

Since 1968, it has been believed that noise vibrations travel through the thin bony walls of toothed whales' lower jaw and onto the fat body attached to the ear complex. This research shows however that the thin bony walls do not transmit the vibrations. In fact they enter through the throat and then pass to the bony ear complex via a unique fatty channel.

Despite the Cuvier's beaked whale being a rare and little-known specie, Dr Cranford and his team started the work on it because over recent years there have been instances when this type of whale has stranded after exposure to intense sound, making them an ideal starting point for research into underwater communication.

*The paper "Acoustic pathways revealed: Simulated sound transmission and reception in Cuvier's beaked whale" was published in Bioinspiration and Biomimetics 3, 1 (March 2008) 016001)

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Beaked whales - into the abyss

By Richard Black
Environment correspondent, BBC News website, the Canary Islands

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A Cuvier's beaked whale makes a rare foray to the surface

Most articles about scientific subjects start by telling you what people have discovered about something.

This one is mainly about what people have not discovered about something.

"There's not much known about these creatures - where they live, their lifestyle," says Ted Cranford from San Diego State University in California, US.

"In fact, they might be the least understood group of large mammals on Earth."

The creatures in question are beaked whales - rarely seen, elusive, private, yet the subject of some attention in recent years because of the damage that military sonar systems appear to inflict on them.

This summer, the research vessel Song of the Whale is attempting to fill in some of the gaps in our understanding as it sails in and around the Canary Islands, home to several beaked whale species.

Operated by the International Fund for Animal Welfare (Ifaw), the yacht's main research tools are hydrophones - underwater microphones - that listen for and track the whales' characteristic high-frequency clicks.

And there is much to discover.

"Some species have never been seen alive, and these are animals as big as an elephant," says Vassili Papastavrou, a whale biologist with Ifaw who is on board Song of the Whale.

Just about the most obvious question you could ask about any kind of animal is "how many of them are there?".

Well, we have no idea - for any of the beaked whale species.

So let us take another obvious question: how many species are there?

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Nobody knows how many species of beaked whales exist

Once again, the answer is unclear.

The 2002 reference work Sea Mammals of the World book, written by leading lights in the cetacean academic world, lists 21.

But, it says, Arnoux's beaked whale may actually be the same as Baird's, while DNA analysis suggests the apparently single species of southern bottlenose whale could be two.

The International Union for the Conservation of Nature (IUCN), in its Red List of Threatened Species, lists 17.

And, to drive the point home, the list says that for 15 of those species, there is simply not enough data to know whether they are threatened with extinction to any degree or not.

Fat bodies

The kind of data gathered by Song of the Whale and other missions around the world gives snapshots of how the animals behave.

But for most beaked whale species, more data has come down the years from examination of dead animals - for some species, corpses are the only source, as they have never been seen alive.

Sea Mammals of the World notes dryly that the northern bottlenose whale is the best understood of all the species because it used to be commercially hunted; and some hunters kept good records of what they caught and what they found.

From a well-preserved corpse - even better, from many corpses - scientists can determine an animal's size, gain clues to its diet and longevity and take DNA samples for analysis.

They can also look at how species have adapted to the environment they live in.

And perhaps the best understood and most fascinating adaptation of beaked whales is in their heads.

Head gear

Over millennia of evolution, this family has developed an acoustic echo-location system that uses windpipes to generate sound, fat to focus it and bone structures that help channel reflections back to the ears.

The basic structure has been known for decades; but last year Ted Cranford had a unique opportunity to get a closer view.

A Cuvier's beaked whale washed up on the shores of Oregon. The people who found it managed to get the head quickly frozen; and Dr Cranford persuaded those in charge of Hill Air Force Base nearby to let him put it through a scanner routinely used for examining rocket motors.

The scan, which took several days, showed that the conventional view of sound production was about right.

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Clicks are generated when a structure just below the blowhole known as "monkey's lips" smacks together.

That generates a wave radiating spherically outwards, which is transformed into a directionally forward-focussed plane wave as it passes through a fat "melon" - an acoustic lens.

So the sound - too high-pitched for a human to hear - shoots out in front of the whale, and if it hits food, such as a squid, a portion is reflected.

The reflection was thought to travel to the whale's ears, via its lower jawbone. But the scan suggested a more important route is under the bone. Air sacs are perfect acoustic mirrors

Ted Cranford

Top of head for transmitting, bottom of head for receiving; a neat system.

The sound reception part appears to be very complex, involving fat bodies that focus sound and air sacs that reflect it.

"The whales need to be able to isolate their ears from each other in order to maintain their directional sense, and one of the best ways to do that is through air sacs."

The use of air sacs is almost incredible when you think that the whales are diving as deep as 2km (1.2 miles), where the pressure equates to 20 megapascals (about 200 atmospheres).

The whales' lungs collapse as they dive, a defensive mechanism against damage from the huge disparity of water pressure outside and air pressure inside; yet somehow the air sacs channelling sound, which appears to be key to the whales' hunting success, stay operational.

First light?

What we know about beaked whales may be fascinating; but it is dwarfed by our ignorance.

Ifaw believes its line of research, concentrating on observing animals in the wild, can answer questions about their behaviour that autopsies of dead whales cannot address.

"This kind of work led to the beginning of our understanding of social structures, such as with the sperm whale," says Mr Papastavrou.

"But then, sperm whales are incredibly loud. Beaked whales use such high frequencies that you can't even hear them without specialised equipment."

As I sit in Song of the Whale's cabin, the specialised equipment is deployed behind the boat, and sounds of beaked whales are being registered.

Scientists now understand the clicks well enough to distinguish between the various species seen here, such as Cuvier's and Blainville's beaked whales and the northern bottlenose whale.

But that is a far cry from what we perhaps ought to know - how they live, where they go, how many there are and what threats they face.

I wonder how much luck we will have filling in the gaps.


Edited by Taipan, Oct 12 2017, 01:30 PM.
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Beaked whale is deep-dive champion

By Jonathan Amos
Science correspondent, BBC News
26 March 2014 Last updated at 21:22

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The elusive creatures are very difficult to study

Cuvier's beaked whales are likely to be the most extreme breath-holders among marine mammals.

A satellite tag attached to one of these animals, swimming off the coast of California, recorded a dive to nearly 3km below the ocean surface that lasted 137 minutes.

This performance exceeds that for any southern elephant seal, which is also known to be an extreme breath-holder.

The Cuvier's record-breaking dive is reported in the journal Plos Biology.

Erin Falcone is a research biologist with the Cascadia Research Collective in Washington State, US, which led the research project.

She told BBC News that beaked whales had very high levels of the myoglobin protein in their muscles, to the point where the tissues appeared almost black.

This functions like haemoglobin in the blood, allowing the whales to store much higher levels of oxygen, and thus breathe less frequently while remaining active.

"One key adaptation that seems to allow beaked whales to dive more deeply than other species is a dramatic reduction in air spaces within their bodies," she added.

"It is the presence of air spaces within the body that would crush a human at a fraction of the depths these whales can dive.

"Reduction in air spaces not only makes them more 'crush resistant', but also likely serves to reduce the uptake of dissolved gases into their tissues - which can lead to decompression sickness or 'the bends'."

Sizeable ability

Cuvier's beaked whales have long been recognised as expert divers, but their precise abilities have been uncertain because of the paucity of data detailing their behaviour in the wild.

The Cascadia group and colleagues managed to put tags on eight animals, collecting over 3,700 hours of diving data.

This information covered more than 1,000 individual deep-dives, averaging depths of 1,400m; and some 5,600 shallow dives, averaging about 275m down.

The prevalent behaviour, says the team, is for a single deep foraging dive followed by a series of shallow dives. The time spent at the surface in between each dive can be very short - just a few minutes.

The deepest recorded dive was to 2,992m, lasting 137.5 minutes, beating the maximum duration for a diving marine mammal of 2,388m, for a duration of 120 minutes, reported for a southern elephant seal.

Dr Paul Jepson from the Zoological Society of London was not connected with the study. He told BBC News: "This paper is incredible for how deep and long these relatively small cetacean species can dive. As a general rule, dive depth and duration tend to scale with body size and body mass - but Cuvier's (adults around 2,500kg) are much smaller than other deep-diving species like sperm whales (up to 57,000kg).

"Of course, what we really need is more tags on more animals. But people who study Cuvier's will tell you these animals are incredibly shy and it's very difficult to get near them to attach a tag."

Sonar concerns

One interesting aspect of the study was its location - within the Southern California Anti-Submarine Warfare Range.

This is surprising because Cuvier's beaked whales are thought to be particularly susceptible to the disturbance caused by military sonar. Many strandings of the species have been reported coincident with military exercises.

The fact that the study animals persisted inside the range hints that they may have become habituated to sonar. But Erin Falcone urged some caution on this interpretation.

"The area where we conducted our study is one of the most heavily used sonar training areas in the world, and when we began working there we were shocked to find as many Cuvier's beaked whales as we did, given that they seem so sensitive to this type of disturbance elsewhere.

"We are actively working to identify periods of time when the whales we tagged were likely exposed to sonar (which has been no small challenge) to see how their behaviour changed, since it is hard to imagine that they are not affected in some way, and understanding how they alter their behaviour here might help to protect beaked whales elsewhere.


First Long-Term Behavioral Records from Cuvier’s Beaked Whales (Ziphius cavirostris) Reveal Record-Breaking Dives

Gregory S. Schorr, Erin A. Falcone, David J. Moretti, Russel D. Andrews
Published: March 26, 2014DOI: 10.1371/journal.pone.0092633

Cuvier’s beaked whales (Ziphius cavirostris) are known as extreme divers, though behavioral data from this difficult-to-study species have been limited. They are also the species most often stranded in association with Mid-Frequency Active (MFA) sonar use, a relationship that remains poorly understood. We used satellite-linked tags to record the diving behavior and locations of eight Ziphius off the Southern California coast for periods up to three months. The effort resulted in 3732 hr of dive data with associated regional movements – the first dataset of its kind for any beaked whale – and included dives to 2992 m depth and lasting 137.5 min, both new mammalian dive records. Deep dives had a group mean depth of 1401 m (s.d. = 137.8, n = 1142) and duration of 67.4 min (s.d. = 6.9). The group mean time between deep dives was 102.3 min (s.d. = 30.8, n = 783). While the previously described stereotypic pattern of deep and shallow dives was apparent, there was considerable inter- and intra-individual variability in most parameters. There was significant diel behavioral variation, including increased time near the surface and decreased shallow diving at night. However, maximum depth and the proportion of time spent on deep dives (presumed foraging), varied little from day to night. Surprisingly, tagged whales were present within an MFA sonar training range for 38% of days locations were received, and though comprehensive records of sonar use during tag deployments were not available, we discuss the effects frequent acoustic disturbance may have had on the observed behaviors. These data better characterize the true behavioral range of this species, and suggest caution should be exercised when drawing conclusions about behavior using short-term datasets.

Edited by Taipan, Oct 12 2017, 01:28 PM.
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Scientists eavesdrop on little-known beaked whales to learn how deeply they dive

Date: October 11, 2017
Source: NOAA Northeast Fisheries Science Center

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Gervais' beaked whale.
Credit: NOAA Fisheries/Southeast Fisheries Science Center

Scientists have reported the first dive depths for Gervais' and True's beaked whales, two of the least known beaked whale species known as mesoplodonts. The study is also the first to use a towed linear hydrophone array to document dive depths for beaked whales, and researchers say it's a promising method to obtain dive depths for other beaked whale species.

The findings by NOAA scientists from the Northeast Fisheries Science Center (NEFSC) in Woods Hole, Mass. and a colleague now at Hydroacoustics Inc in Rochester, NY were recently reported in the Journal of the Acoustical Society of America.

"Much of what we know about beaked whales and their dive depths is from two or three species, and from a few locations. We know so little about Gervais' and True's beaked whales, but now we know something about how deep they dive and at what depths they are foraging, so this is a step forward," said Annamaria Izzi DeAngelis, lead author of the study and a marine mammal researcher in the passive acoustics group at the NEFSC.

The linear towed array is made up of a long cable to which a depth sensor and a series of eight hydrophones -- underwater microphones -- are attached. The array is towed 300 meters, roughly 1,000 feet, behind the NOAA Ship Henry B. Bigelow to reduce the ship's noise on the array. It is a passive acoustic approach, meaning the array just listens and doesn't emit any sounds, while active acoustics such as echosounders (also called fish finders) are devices making noise and then listening for that sound.

Average dive depth for Gervais' or True's beaked whales heard in the study was 870 meters (about 2,850 feet, or just over half a mile deep). Researchers also found that the average dive depth of the much better known Cuvier's beaked whale was 1,158 meters (about 3,800 feet, or more than three quarters of a mile deep). Pre-existing dive depth knowledge about Cuvier's beaked whales from tagging studies helped the researchers validate their results.

Scientists used acoustic recordings collected over 33 days in July and August 2013 from the Henry B. Bigelow in waters from New Jersey to southern Canada along the continental slope and the floor of the deep sea. The data were gathered as part of an annual survey of marine mammals in the North Atlantic conducted by the NEFSC.

Descriptions of clicks, high frequency sounds made by marine mammals, exist for Northern bottlenose dolphins and for Cuvier's, Sowerby's and Blainville's beaked whales, but next to nothing is known about the remaining North Atlantic beaked whale species, and especially about True's beaked whales. What little information there is comes from dead stranded animals.

The human ear can't detect the higher frequency clicks made by beaked whales. "Since we cannot rely on our hearing, we use spectrograms to see the sounds," DeAngelis explained. A spectrogram provides a visual image of the whales' frequencies.

"We had two click types, one that we identified as Cuvier's beaked whale and another that looked similar to Gervais' but could also be True's beaked whale," DeAngelis said. Distinguishing True's clicks is difficult since nothing is known about them, which led DeAngelis and colleagues to use a Gervais'/True's category for Mesoplodon clicks.

Beaked whales live in deeper waters offshore, are skittish, and spend little time on the surface, making it difficult to see them to study their behavior. Researchers believe the clicks occur when the whales are foraging, starting at around 400 meters depth (about a quarter-mile deep) and continue as they descend to find food, sometimes down to 3,000 meters (just under two miles deep). Since placing tags on individual animals is time-consuming and difficult to do, passive acoustics -- devices that can listen for and record information about sounds the whales make -- provide another option.

"When tags that record depth over time are attached to individual animals, we get high resolution dive profiles on a small number of individuals in specific locations. The hydrophone array collects lower resolution information but on a large number of animals all over the world," DeAngelis said. "Because it is hard to tag beaked whales and towed linear hydrophone arrays are commonly used in marine mammal passive acoustics, this method opens doors to allow more depth and ecological data to be collected on a wider range of beaked whale species."

Depths of beaked whales were calculated by using the time difference between when a click was first received by the array and the time it took for its surface-reflected echo to also reach the hydrophones. Pamguard, a free open source computer program, provided a two-dimensional position for the clicks, and another code, developed by study co-author Robert Valtierra, extracted the time difference between the direct arrival of the click and the surface-reflected arrival. Combining the 2-D position with the time delay between a click and its surface reflection provided the depth of a foraging beaked whale.

Gervais' beaked whales (Mesoplodon europaeus), sometimes called the Antillean or Gulf Stream beaked whale, grow 15-17 feet long and weigh about 2,640 pounds. They are usually found alone or in small social groups and feed on squid, shrimp and small fish. They live in the deep warm waters of the Caribbean, Gulf of Mexico and East Coast of the U.S. south of New England. They are also found in the eastern North Atlantic from the British Isles to western Africa.

True's beaked whales (Mesoplodon mirus) are medium sized whales that are hard to distinguish from Gervais' and other beaked whales. They are found in warm temperate waters off the U.S. East Coast and southern Canada, off the British Isles and western Europe, off western Africa and South Africa, and south of Australia. The first underwater footage of a True's beaked whale was recorded in 2013 off the Azores in the North Atlantic.

Cuvier's beaked whales (Ziphius cavirostris) are one of the most sighted and studied beaked whales in the world. Sometimes called goose-beaked whales, they can reach lengths of 15-23 feet and weigh 4,000 -- 6,800 pounds. Cuvier's beaked whales live in temperate, subtropical and tropical waters and prefer the deeper waters of the continental slope and areas around steep underwater geologic features like seamounts and submarine canyons. > are one of the most sighted and studied beaked whales in the world. Sometimes called goose-beaked whales, they can reach lengths of 15-23 feet and weigh 4,000 -- 6,800 pounds. Cuvier's beaked whales live in temperate, subtropical and tropical waters and prefer the deeper waters of the continental slope and areas around steep underwater geologic features like seamounts and submarine canyons.

The study was funded by NOAA Fisheries, the U.S. Navy N45 Program, and the Bureau of Ocean Energy Management. Data were collected as part of the Atlantic Marine Assessment Program for Protected Species (AMAPPS) program.

Story Source: NOAA Northeast Fisheries Science Center. "Scientists eavesdrop on little-known beaked whales to learn how deeply they dive." ScienceDaily. www.sciencedaily.com/releases/2017/10/171011120307.htm (accessed October 11, 2017).

Journal Reference:
Annamaria Izzi DeAngelis, Robert Valtierra, Sofie M. Van Parijs, Danielle Cholewiak. Using multipath reflections to obtain dive depths of beaked whales from a towed hydrophone array. The Journal of the Acoustical Society of America, 2017; 142 (2): 1078 DOI: 10.1121/1.4998709

Beaked whales are deep divers, emitting echolocation clicks while at depth. Little is known about the dive behavior of most species; however, passive acoustic data collected with towed hydrophone arrays can provide depth information using multipath reflections of clicks coupled with a two-dimensional localization of the individual. Data were collected during a shipboard survey in the western North Atlantic Ocean using a towed linear hydrophone array. Beaked whale tracks were classified as either Cuvier's (Ziphius cavirostris) or Gervais'/True's (Mesoplodon europaeus/Mesoplodon mirus). Weighted species average depths and weighted species standard deviations were 1158 m ± 287 m for Cuvier's (n = 24), and 870 m ± 151 m for Gervais'/True's (n = 15). Depth uncertainties ranged from 3% to 142% of the average depth. Slant ranges were corrected for depth to provide average horizontal perpendicular distance estimates. The average horizontal perpendicular distance distribution exhibited fewer detections in the first bin than the second. This is the first report of dive depths for Gervais'/True's beaked whales and use of this method to obtain depths for beaked whales using a towed linear array.


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.

Edited by Taipan, Oct 12 2017, 02:45 PM.
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