Utente:Panjabi/Prove: differenze tra le versioni
Contenuto cancellato Contenuto aggiunto
Riga 617:
* [http://www.tmmc.org/learning/education/whales/blue.asp Blue Whale at the Marine Mammal Center]
* [http://www.birds.cornell.edu/brp/SoundsBlueWhale.html Blue Whale vocalizations] - [[Cornell University|Cornell]] Lab of Ornithology - Bioacoustics Research Program
{{Tassobox
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|nome=Balenottera azzurra pigmea <ref name=MSW3>{{MSW3|id=14300020}}</ref>
|statocons=DD
|statocons_versione=iucn3.1
|statocons_ref=<ref name="iucn">{{IUCN|summ=2479|autore=Taylor, B.L. & Notarbartolo di Sciara, G. (Cetacean Red List Authority) 2008}}</ref>
|immagine=[[Immagine:Pygmy blue whale.jpg|230px]]
|didascalia=
<!-- CLASSIFICAZIONE: -->
|dominio=
|regno=[[Animalia]]
|sottoregno=
|superphylum=
|phylum=[[Chordata]]
|subphylum=
|infraphylum=
|microphylum=
|nanophylum=
<!-- PER TUTTI: -->
|superclasse=
|classe=[[Mammalia]]
|sottoclasse=
|infraclasse=
|superordine=
|ordine=[[Cetacea]]
|sottordine=
|infraordine=
|superfamiglia=
|famiglia=[[Balaenopteridae]]
|sottofamiglia=
|tribù=
|sottotribù=
|genere='''[[Balaenoptera]]'''
|sottogenere=
|specie='''[[Balaenoptera musculus|B. musculus]]'''
|sottospecie='''B. m. brevicauda'''
<!-- NOMENCLATURA BINOMIALE: -->
|biautore=
|binome=
|bidata=
<!-- NOMENCLATURA TRINOMIALE: -->
|triautore=Ichihara
|trinome=Balaenoptera musculus brevicauda
|tridata=[[1966]]
<!-- ALTRO: -->
|sinonimi?=
|sinonimi=
|nomicomuni=
|suddivisione=
|suddivisione_testo=
}}
La '''balenottera azzurra pigmea''' ('''''Balaenoptera musculus brevicauda''''' <span style="font-variant: small-caps">Ichihara, [[1966]]</span>) è una sottospecie di [[balenottera azzurra]] (''Balaenoptera musculus'') diffusa nell'[[Oceano Indiano]] e nell'[[Oceano Pacifico]] meridionale.
Con una lunghezza massima di 24 metri, è più piccola delle altre sottospecie riconosciute, ''B. m. musculus'' e ''B. m. intermedia'', che possono raggiungere i 29 metri di lunghezza, da cui il nome comune <ref name="BBC">{{cite web|url=http://news.bbc.co.uk/2/hi/science/nature/3003564.stm|title=Science seeks clues to pygmy whale|author=Alex Kirby|publisher=BBC News|date=19 June 2003|accessdate=15 June 2007}}</ref> .
Secondo le osservazioni compiute da quando la sottospecie è stata descritta, nel 1966, la balenottera azzurra pigmea si differenzia dalle «vere» balenottere azzurre per un certo numero di caratteristiche fisiche. Ha:
* placche dei fanoni più larghi e più brevi,
* una coda più corta e, quindi, un corpo proporzionalmente più lungo davanti alla pinna dorsale, e
* una testa più grande rispetto alle dimensioni corporee.
La coda più corta dà a questa sottospecie una forma a [[girino]] The shorter tail gives the Pygmy Blue Whale more of a [[tadpole]]-like shape, and reflects in differences in diving behaviour: whereas in the "true" Blues there is a delay between the submergence of the [[dorsal fin]] and the [[caudal peduncle]], in Pygmy Blue Whales the dorsal and peduncle submerge simultaneously. Pygmy Blue Whales also tend to be darker than the other subspecies of Blue Whale and the shape of their blowhole is different.<ref name="BBC" /><ref>{{cite web|url=http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=36|title=Balaenoptera musculus — Blue Whale|publisher=Australian Government: Department of the Environment and Water Resources|___location=Canberra|date=2007|accessdate=15 June 2007}}</ref>
The Pygmy Blue Whale is the only one of the three identifiable subspecies to be found regularly in tropical waters. It occurs from the sub-Antarctic zone up to the
southern Indian Ocean and south western Pacific Ocean, breeding in the Indian and South Atlantic oceans and travelling south to the Antarctic to feed.<ref name="BBC" /><ref name="Can">{{cite web|url=http://www.wildwhales.org/cetaceans/blue/sr_blue_whale_e.pdf.pdf|publisher=Committee on the Status of Endangered Wildlife in Canada|date=2002|title=Assessment and Update Status Report on the Blue Whale ''Balaenoptera musculus''|accessdate=15 June 2007}}</ref>
A fourth subspecies, ''B. m. indica'', was identified by [[Edward Blyth|Blyth]] in 1859 in the northern Indian Ocean, but difficulties in identifying distinguishing features for this subspecies lead to it being used a synonym for ''B. m. musculus''. It is now thought it could be the same subspecies as the Pygmy Blue Whale. Records for Soviet catches seem to indicate that the female adult size is closer to that of the Pygmy Blue than ''B. m. musculus'', although the populations of ''B. m. indica'' and ''B. m. brevicauda'' appear to be discrete and the breeding seasons differ by almost six months.<ref>{{cite web|title=Past and present distribution, densities and movements of blue whales in the Southern Hemisphere and adjacent waters|url=http://www.iwcoffice.org/_documents/sci_com/SC59docs/SC-59-ForInformation26.pdf|author=T. A. Branch, K. M. Stafford ''et al.''|publisher=International Whaling Commission|date=2007|accessdate=15 June 2007}}</ref>
Pygmy Blue Whales are believed to be more numerous than the other subspecies. Estimates put their numbers at around 10,000 individuals whereas the other subspecies combined are estimated to total around 5,000. Although the designation is widely accepted, because of the relatively healthy stocks of Pygmy Blues compared to the other subspecies, The Committee on the Status of Endangered Wildlife in [[Canada]] has questioned whether the sub-classification of the Pygmy Blue Whale has been driven by the interests of the whaling industry.<ref name="Can" />
==Specimens==
*[http://collections.tepapa.govt.nz/objectdetails.aspx?oid=242663 MNZ MM002191], collected Motutapu Island, Hauraki Gulf, New Zealand, September 1994.
==Note==
<references/>
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