أشلاق (القروش و الشفانين) (sharks and rays) >
Rajiformes (Skates and rays) >
Rajidae (Skates)
Etymology: Dipturus: Greek, di = two + Greek, pteryx = fin (Ref. 45335).
More on author: Smith.
Environment: milieu / climate zone / نطاق العمق / distribution range
البيئة
بحري القاع; نطاق العمق 50 - 457 m (Ref. 5578). Subtropical; 26°S - 36°S, 12°E - 29°E (Ref. 114953)
Southeast Atlantic: known only from Lüderitz, Namibia to Port Alfred, Eastern Cape (South Africa)
الحجم / وزن / العمر
النضج: Lm ? range ? - ? cm
Max length : 130 cm TL ذكر/ مختلط الجنس; (Ref. 114953)
وصف مختصر
مفاتيح التعريف | الوصف الخارجي | قياسات المظهر الخارجي
A striking two-toned longnose skate, medium brown above and abruptly dark grey below, with a large, conspicuous, dark brown blotch on the upper base of each pectoral fin (Ref. 5578). Snout moderately elongated and bluntly triangular, and tail stout, not conspicuously swollen and about equal to body length; pectoral disc with broadly rounded corners and smooth underside without denticles; thorns at nape and along midline of back and tail to 1st dorsal fin, nape spine enormous in young (Ref. 5578). Hatchlings and juveniles with wide-spaced black spots on upper disc, inconspicuous or lost in adolescents and adults; adults sometimes with numerous small white spots (Ref. 5578). Underside with numerous black pores (Ref. 5578).
Body shape (shape guide): other.
Found on soft bottoms of the outer shelf and upper slope (Ref. 5578). Feeds on bony fish, crabs, shrimp, mysids, mantis shrimp, euphausiids, bivalves and cuttlefish (Ref. 5578). Oviparous (Ref. 50449). Eggs have horn-like projections on the shell (Ref. 205). Males reaches maturity at 88-96 cm TL, females possibly slightly larger off Western than Southern coast of South Africa; hatching size at ca. 19 cm TL (Ref. 114953). Commonly taken by hake trawlers (Ref. 5578). Extremely slippery when caught (Ref. 5578).
Life cycle and mating behavior
النضج | التكاثر | وضع البيض | بيض | الخصوبة | Larvae
Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). Eggs have horn-like projections on the shell (Ref. 205).
McEachran, J.D. and K.A. Dunn, 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes: Rajidae). Copeia 1998(2):271-290. (Ref. 27314)
IUCN Red List Status (Ref. 130435: Version 2025-1)
استخدامات بشرية
مصائد: غير ذات اهمية
أدوات
تقارير خاصة
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مصادر علي الأنترنت
Estimates based on models
Preferred temperature (مرجع
123201): 9.2 - 16.7, mean 11 °C (based on 41 cells).
Phylogenetic diversity index (مرجع
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00372 (0.00251 - 0.00550), b=3.20 (3.08 - 3.32), in cm total length, based on LWR estimates for this species & Genus-body shape (Ref.
93245).
مستوى غذائي (مرجع
69278): 4.1 ±0.69 se; based on food items.
Generation time: 22.0 ( na - na) years. Estimated as median ln(3)/K based on 2
growth studies.
المرونه (مرجع
120179): منخفض, الحد الزمني الأدني لتضاعف عدد أفراد المجتمع 4.5-14 سنة (Fec assumed to be <100).
Fishing Vulnerability (Ref.
59153): Very high vulnerability (75 of 100).
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