Cystophora cristata Erxleben, 1777

Koretsky, I. A., Rahmat, S. J. & Peters, N., 2014, Remarks On Correlations And Implications Of The Mandibular Structure And Diet In Some Seals (Mammalia, Phocidae), Vestnik Zoologii 48 (3), pp. 255-268 : 259-260

Cystophora cristata Erxleben, 1777 ( fig. 3 , table 1)

The mandibular ramus is considerably superior to the tooth row, directed posterodorsally and is slightly wider than the body. The posterior border of the coronoid process takes on a hook-shape and slopes slightly toward the condyloid process in both sexes. The condyloid process is located slightly superior to the level of the mandibular notch in females, while in males it is significantly higher (black arrows in fig. 3 ). Overall, the mandibular notch is considerably wider in males than in females. A relatively small depression is present on the caudal border of the ramus ( fig. 3 ). The angular process is rather weak, creating a distinctly smooth and rounded mandibular angle. The condyloid angle (° 33° and ♀ 28°; table 1) is wide and shows a large gape.

The masseteric fossa is less distinctly outlined than that of female Mirounga angustirostris , and the width measures approximately the same (4.5 cm in both sexes of Cystophora cristata ), even though the overall size of the body is much smaller. Like in M. angustirostris , the fossa seems to extend the entire length of the ramus ( fig. 3 ). The masseteric fossa is relatively smooth in the middle, with no obvious significant ridges or grooves for muscle attachment. The C. cristata coronoid process is much narrower, especially towards the base, but the height is approximately the same as that of female M. angustirostris . The overall size of the C. cristata mandible is smaller than that of male and female M. angustirostris , and both the masseter and temporalis muscle attachments are weaker and less defined in C. cristata . Similar to Mirounga , the C. cristata mandible has weak teeth.

The stomach content of hooded seals ( C. cristata ) describes diets consists of halibut, Greenland cod, herring, flounder, octopus, shrimp, squid and mussels (Kovacs, Lavigne,

Рис. 3. Подсемейство Cystophorinae : левая челюсть Cystophora cristata : А — °, NMNH 269130, развёрнута; B — ♀, NMNH 188956 , вид с губной стороны .

1986). The average diving depth of young pups is 75 m ( Scholander, 1940) while adults have been known to dive to 180 m in order to obtain food ( King, 1983).

Figures

Fig. 3. Subfamily Cystophorinae: left mandible of Cystophora cristata: A— °, NMNH 269130, reversed; B — ♀, NMNH 188956, in labial views.