Elasmobranchii (sharks and rays) > Rajiformes
(Skates and rays) > Arhynchobatidae
Etymology: simoterus: Name probably derived from the comparative tense of the Greek σιμóς, meaning 'pug-nosed', referring to its rounded snout (Ref. 89865).
Environment: milieu / climate zone / depth range / distribution range
Marine; demersal; depth range 96 - 540 m (Ref. 89865). Temperate
Northwest Pacific: off northern Japan.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 101 cm TL male/unsexed; (Ref. 89865)
Morphology | Morphometrics
This species is distinguished from all other members of the subgenus Arctoraja by having a complete row of dorsal thorns, narrow interdorsal space, high count of precaudal vertebrae, and COI haplotype. It is further distinguished from B. parmifera by its narrower interdorsal space 0.5-1.0% TL (vs. 1.0-3.9% TL), number of precaudal and caudal vertebrae 41 and 90 (vs. 32-40 and 82-89), tail thorns 22-28 (vs. 15-23), larger orbit 4.3-5.3% TL (vs. 2.6-4.8% TL), 3 postdorsal foramina slightly smaller posteriorly, posteriormost postventral foramina 4 times larger than preceding 6 foramina (vs. anterior- and posterior-most postdorsal and postventral foramina of the scapulacoracoid larger than 3 intervening foramina), distal projection of the ventral marginal directed distally (vs. distolaterally), ventral terminal lanceolate (vs. tear-drop shaped), dorsal and ventral marginals extending farther distally to distal tip of dorsal terminal 3 (vs. extending to about a quarter the length of dorsal terminal 2); from B. panthera by its narrow interdorsal space width (vs. 1.4-3.1% TL); anterior portion of body shorter and narrower (vs. longer and wider); tail shorter (vs. longer); posterior fontanelle narrowly elongate (vs. pear-shaped); internal carotid foramina widely separated (vs. foramina in a single median pit), foramen of scapulocoracoid all large (vs. anterior postdorsal foramen large, others much smaller), ventral terminal lanceolate (vs. tear-drop shaped); from the incompletely thorned B. smirnovi by its higher number of vertebrae 131 (vs. 118-127), more precaudal vertebrae 41 (vs. 31-38), smaller mouth size 8.1-9.1% TL (vs. 8.3-11.6% TL), neurocranium with 2 fontanelles (vs. 1), internal carotid foramina widely separated (vs. close together in a single pit), scapulocoracoid with 3 foramina, more posterior each slightly smaller (vs. 5 foramina, anterior- and posteriormost larger than three intermediates), and pelvic girdle with two obturator foramina widely spaced (vs. close together) (Ref. 89865).
Oviparous. Distinct pairing with embrace. Young may tend to follow large objects, such as their mother (Ref. 205). Eggs are oblong capsules with stiff pointed horns at the corners deposited in sandy or muddy flats (Ref. 205). Egg capsules are 12.0 cm long and 9.0 cm wide (Ref. 41253).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449). Distinct pairing with embrace. Young may tend to follow large objects, such as their mother (Ref. 205). 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. 125652)
Threat to humans
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Preferred temperature (Ref. 123201
): 1 - 17.6, mean 11.8 °C (based on 33 cells).
Phylogenetic diversity index (Ref. 82804
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00575 (0.00290 - 0.01143), b=3.09 (2.92 - 3.26), in cm total length, based on LWR estimates for this (Sub)family-body shape (Ref. 93245
Trophic level (Ref. 69278
): 4.0 ±0.7 se; based on size and trophs of closest relatives
Resilience (Ref. 120179
): Low, minimum population doubling time 4.5 - 14 years (Fec assumed to be <100).
Fishing Vulnerability (Ref. 59153
): High vulnerability (61 of 100).