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FishMammalsSpecies Animal

Ziphius cavirostris

Ziphius cavirostris

The Cuvier’s beaked whale or goose-beaked whale, ziphius (Ziphius cavirostris G. Cuvier, 1823) is a cetacean belonging to the Ziphidae family.

Systematic –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Animalia,
Phylum Chordata,
Mammalia class,
Order Cetacea,
Suborder Odontoceti,
Ziphidae family,
Genus Ziphius,
Species Z. cavirostris.
The terms are synonymous:
– Aliama desmarestii Gray, 1864;
– Aliama indica Gray, 1865;
– Choneziphius indicus (Van Beneden, 1863);
– Delphinorhynchus australis Burmeister, 1865;
– Delphinus desmaresti Risso, 1826;
– Delphinus philippii Cocco, 1846;
– Epiodon australe Burmeister, 1867;
– Epiodon australis Gray, 1871;
– Epiodon chathamensis (Hector, 1873);
– Epiodon chathamiensis Hector, 1873;
– Epiodon cryptodon Gray, 1870;
– Epiodon desmarestii Carus, 1893;
– Epiodon heraultii Gray, 1872;
– Epiodon patachonicum Burmeister, 1867;
– Hyperodon semijunctus Cope, 1865;
– Hyperondon semijunctus Hall & Kelson, 1959;
– Hyperoodon capensis Gray, 1865;
– Hyperoodon desmarestii Gray, 1850;
– Hyperoodon doumetii Gray, 1850;
– Hyperoodon gervaisii Duvernoy, 1851;
– Hyperoodon semijunctus (Cope, 1865);
– Petrorhynchus capensis Gray, 1865;
– Petrorhynchus indicus Gray, 1865;
– Petrorhynchus mediterraneus Gray, 1871;
– Ziphiorrhynchus australis (Trouessart, 1904);
– Ziphiorrhynchus cryptodon Burmeister, 1865;
– Ziphius aresques Gray, 1871;
– Ziphius australis (Burmeister, 1865);
– Ziphius australis (Trouessart, 1904);
– Ziphius cavirostris subsp. indicus Deraniyagala, 1945;
– Ziphius chatamensis Lahille, 1899;
– Ziphius chathamensis Flower, 1885;
– Ziphius chathamiensis Iredale & Troughton, 1934;
– Ziphius cryptodon Fischer, 1857;
– Ziphius decavirostris Gray, 1871;
– Ziphius gervaisii (Duvernoy, 1851);
– Ziphius grebnitzkii Stejneger, 1883;
– Ziphius indicus P.-J.van Bénéden, 1863;
– Ziphius novaezealandiae Haast, 1876;
– Ziphius savii Richiardi, 1873;
– Ziphius semijunctus (Cope, 1865);
– Zyphius chathamensis Moreno, 1895.

Geographic Distribution and Habitat –
The Ziphius cavirostris is a cetacean, the only species of the genus Ziphius, with a cosmopolitan distribution.
This species occurs in the North Pacific, is found as far north as the Aleutians and in the North Atlantic as far west as Atlantic Canada and Shetland in the east. In the Southern Hemisphere, it is found as far south as Tierra del Fuego, South Africa, South Australia, New Zealand, and the Chatham Islands. It also frequents inland bodies of water such as the Gulf of Mexico, the Caribbean and the Mediterranean Sea. The Mediterranean population may be genetically distinct from the North Atlantic populations.
It is one of the most common and abundant cetaceans, with a global population that probably exceeds 100,000 specimens. An estimated 80,000 are found in the eastern tropical Pacific, nearly 1,900 off the U.S. West Coast (excluding Alaska), and more than 15,000 off Hawaii. The population in the Gulf of Mexico is extremely small and there have been calls for this area to become a protected species. As of 2019 this was rejected on the basis that there was insufficient scientific evidence to consider them a distinct population segment (DPS) under the Endangered Species Act (ESA).
Its marine habitat ranges from tropical and cold-temperate waters, up to the 10 °C isotherm; however, it seems absent from polar waters. Unfortunately, almost all the data regarding its distribution comes from the examination of strandings, which certainly does not constitute a direct and totally reliable form of information. It is undoubtedly a pelagic cetacean of temperate and tropical waters, which rarely ventures near the coast and above the continental shelf, but seems to prefer waters where the depth reaches and exceeds 1000 m.

Description –
The Ziphius cavirostris is a cetacean with an average adult size of about 6 m. and maximum measured 7.60 m, with a weight that averages around 3 tons, but which can reach a maximum of 6.
Newborns have an average length of around 2.7 m.
The color varies slightly depending on age and sex. Adult males have a slate gray color over the entire body, except for the head and the back immediately behind it, which are white or whitish. Adult females can have a color ranging from dark gray to reddish brown or milky brown, with a lighter shade of head, although never white as in males; a dark region surrounds the eye, which is often also adorned with two prominent dark crescent-shaped striae, one anterior and one posterior to the eye itself.
The livery of the little one instead seems to be bluish black, with a lighter belly. The background color is also almost always mixed with scratches and light oval-shaped spots. The former, much more frequent on the bodies of adult males, seem to be the result of competitive and aggressive interactions; the latter, perhaps, scars left by lampreys and the small tropical pelagic shark Isistius brasiliensis.
This cetacean has a siluriform body, rather stocky, and a small head, laterally compressed, slightly convex at the top due to the presence of a small melon, with a very short beak. The blowhole is placed on the vertical of the eyes and slightly asymmetrical on the left; it is crescent-shaped with the concavity facing forward. Immediately behind the blowhole there is a depression, typical of the species. The mouth rhyme is short, with a typical sigmoid shape, which looks like a “grin”; the apex of the mandible is decidedly protruding forward, under the upper jaw.
In the gular region it has two grooves, arranged in a V with the vertex facing forward, but which do not join.
The dorsal fin is small and triangular, more or less falcate, and is located at the beginning of the rear third of the body.
The pectoral fins are small and thin (about 1/10 of the total length); when kept close to the body, they fall into a specific depression which is typical of the family.
It has a rather large tail (about ¼ of the total length), with a barely visible or absent interlobar sinus: this is also a characteristic of the family.

Biology –
Ziphius cavirostris has a biology that is not perfectly understood. It seems that there is no precise breeding season.
These cetaceans reach sexual maturity when specimens of both sexes reach 5.5 m in length.
They also have a longevity probably around 40 years.

Ecological Role –
Ziphius cavirostris has a particular taxonomic history. In 1804 Raymond Gorsse found a similar fossil cetacean skull at the mouth of the Galegéon river, near Fos (on the French Mediterranean coast), which was then sent to Paris, to the National Museum. Here it was examined by Cuvier, who later described it, in his work Recherches sur les ossements fossiles, as an extinct cetacean, to which he gave the name Ziphius cavirostris due to the notable development of the prenarial pelvis. Since then skulls of this species appeared here and there in various regions of the world, and were gradually described by the zoologists who dealt with them, always with the creation of new species (hence the numerous synonyms), until the Scottish zoologist Sir Edward Turner, examining a cetacean stranded on the Shetland Islands in 1872, realized that this species was not extinct at all, and that it was a single species described several times with different names. The belief that Ziphius is a monotypic genus has persisted to this day, despite the species demonstrating considerable geographical variability.
Ziphius cavirostris has also been studied more recently through satellite surveys; data indicate that these cetaceans follow a stereotyped dive pattern in which a deep dive greater than 800 m is followed by several shorter, shallower dives. Specimens of this species typically exhibit very short surface intervals (2 to 8 minutes), but rarely spend prolonged intervals at the surface (30 to 310 minutes). Diving behavior shows little variation.
This species holds the record for both the deepest dive ever documented for any mammal, and the longest dive ever documented for any mammal. In 2014, scientists reported that an individual off the coast of California dived to 2,992 m below the ocean surface, the deepest documented dive for any mammal. A 2020 study reported that one specimen made a dive that lasted 222 minutes, the longest dive ever documented for any mammal. Supervising scientist Nicola Hodgkins noted that “recorded dive time of more than three hours is probably not typical, but is instead the result of an individual pushed to their absolute limits.”
It is possible that these cetaceans have developed alterations in metabolism and behavior that allow them to dive deep beyond their expected aerobic capacity. Considering this species’ ability to dive to nearly 3,000 m and stay underwater for hours, there are suggestions that they may be able to collapse the rib cage and perhaps the lungs. They are observed to jump when entering a dive in pelagic depths.
During shallow dives, individuals tend to be silent, perhaps to avoid predators. Below 200 m they use echolocation as part of foraging. Exposure to high levels of noise from anthropogenic sources, such as Navy sonars, appears to disturb their behavior and has been linked to multiple mass stranding events affecting beaked whales.
There are no data regarding its migratory habits. The information on this matter is so fragmentary that it is not possible to outline the social structure of this species. Most observations concern isolated specimens or in small groups of 2-4 specimens. The largest herd known to exist consisted of 25 specimens. The extreme rarity of sightings at sea indicates the great shyness of this species, which certainly works to keep away from boats and human activities. Regarding the production of sounds, there are no details on the matter. Precisely from strandings we know, however, that this cetacean is not as rare as one might assume from the small number of sightings. Almost all of these strandings concern single strandings. Few cases of mass strandings are known: one of 5 specimens in Puerto Rico, another of 6 specimens in the Galápagos, finally two in the Canary Islands, one of which at least 12 specimens. In Liguria, in May 1963, in the space of a few days, as many as 15 specimens beached themselves along a coastline of a few tens of kilometres; technically in this case we cannot speak of a collective stranding, although the individual events were certainly connected to each other.
Among the predators of the Ziphius cavirostris we note the orca. In 1985, off the coast of Finale Ligure, an orca was photographed while removing pieces of meat from a fresh carcass of this cetacean, which in all likelihood it had captured itself. However, the main cause of mortality in the Mediterranean is most likely accidental catches in pelagic drift nets. Finally, it is worth mentioning the hypothesis that at least some of the collective strandings (for example those that occurred in the Canary Islands, and perhaps also the one in Liguria) were in some way correlated with military exercises, and with consequent underwater explosions.
As regards nutrition, from those few stomachs examined, especially of specimens captured off the coast of Japan, it would seem that this cetacean is an opportunistic predator, rather than an eminent teutophagous as is often read. That is, it would feed on the most available prey depending on the case: mainly meso- and bathypelagic squid when it finds itself at depths just under 1000 m, while at greater depths various species of fish become predominant in its diet. In the Mediterranean, evidence from the stomach contents of stranded specimens indicates that it feeds on squid, mainly Histioteuthis reversa, H. bonnellii and Ancistroteuthis lichtensteinii.
This species was included in the IUCN red list as being of least concern in 2008. There are no global estimates of the total population of this cetacean, but its population is believed to be no less than 100,000 individuals. The species has a very wide distribution range and the main threats are high levels of noise caused by man, in particular military sonars, and accidental captures. The combination of its wide distribution and relative abundance is enough to prevent a global decline of more than 30% in three generations.

Guido Bissanti

– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Louisy P., 2016. Guide to the identification of marine fishes of Europe and the Mediterranean. Il Castello Editore, Milan.
– Nikiforos G., 2008. Fauna of the Mediterranean. Giunti Editore, Florence.

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