from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small, pointed dorsal fin. Also called razorback.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any whale with longitudinal skin folds running from below the mouth to the navel, allowing the capacity of the mouth to expand greatly when feeding.
from the GNU version of the Collaborative International Dictionary of English
- n. A very large North Atlantic whalebone whale (Physalus antiquorum, or Balænoptera physalus). It has a dorsal fin, and strong longitudinal folds on the throat and belly. Called also razorback.
from The Century Dictionary and Cyclopedia
- n. A finner-whale of the genus Balænoptera, having short flippers, a dorsal fin, and the throat plicated.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat and a small pointed dorsal fin
When this is combined with the fact that some of the prey that rorquals depend upon, such as krill, are declining, it becomes clear why certain rorqual populations are struggling to recover from the days of commercial whaling.
More significant was the recognition by Larsen that new technologies (particularly the recently invented grenade harpoon gun) would allow hunting of the more difficult but more common rorqual whales (Blue, Fin, Humpback, Sei and Minke Whales) in the Southern Ocean.
Whales include migratory humpback Megaptera novaeangliae (VU) and occasional blue Balaenoptera musculus (EN), rorqual Balaenoptera physalis, sperm Physeter macrocephalus (VU), Bryde's Baleanoptera edeni, killer Orcinus orca, false killer Pseudorca crassidens, pygmy killer Feresa attenuata, Cuvier's beaked Ziphius cavirostris, beaked Mesoplodon sp., shortfin pilot Globicephala macrorhynchus and melon-headed Peponocephala electra whales.
When a rorqual lunges, delicate timing is needed, otherwise the buccal pouch will rapidly fill with seawater and not with prey.
As it swam around, gradually tiring, Williamson approached it in the water and took his photos [the accompanying image, showing a young rorqual that beached in Florida in 2002, is borrowed from VisitGulf. com].
Once a mass of prey is engulfed, a rorqual then has to squeeze the water out through its baleen plates while at the same time retaining the prey.
* Most books on whales state that there are five rorqual species.
A rorqual may engulf nearly 70% of its total body weight in water and prey during this action, which in an adult blue whale amounts to about 70 tons (Pivorunas 1979).
Occasionally rorqual skulls have been discovered in which the long lower jaws have been stuck wedged inside various of the skull openings and with their tips protruding like tusks.
Moving back to the morphology of the rorqual lower jaw, a tall, well-developed coronoid process – way larger than that of any other mysticete – projects from each jaw bone and forms the attachment site for a tendinous part of the temporalis muscle, termed the frontomandibular stay.