blue whale vs Ojiro-ei

Balaenoptera musculus compared with Urogymnus granulatus

Taxonomic Classification

Rank	blue whale	Ojiro-ei
Kingdom same	Animalia (動物)	Animalia (動物)
Phylum same	Chordata (脊索動物)	Chordata (脊索動物)
Class	Mammalia (哺乳類)	Elasmobranchii
Order	Cetacea (Whales & Dolphins)	Myliobatiformes (トビエイ目)
Family	Balaenopteridae (Rorquals)	Dasyatidae
Genus	Balaenoptera (Rorquals)	Urogymnus
Species	Balaenoptera musculus	Urogymnus granulatus

Evolutionary Relationship

blue whale and Ojiro-ei share a common ancestor at the Phylum level: Chordata. (脊索動物)

Conservation Status

blue whale

VU — Vulnerable

Population: ~15.0K

Trend: Increasing ↑

Ojiro-ei

VU — Vulnerable

Physical Characteristics

Attribute	blue whale	Ojiro-ei
Diet	Carnivore	—
Average Lifespan	90 years	—
Average Length	30.0 m	—
Average Weight	150.0 t	—

Habitat & Geographic Range

blue whale

Habitat

Found across multiple habitat types including tropical and subtropical moist broadleaf forests, tropical and subtropical dry broadleaf forests, and tropical and subtropical grasslands and savannas, among 11 distinct biome types. Populations are also found in montane and highland environments at higher elevations.

Range

Widely distributed across Asia (Taiwan), Europe (4 countries), and South America (Colombia, Ecuador). Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Ojiro-ei

blue whale

地球上で生きたことが知られている最大の動物であるシロナガスクジラ（Balaenoptera musculus）は、体長33メートル、体重200トンに達することができ、心臓だけで小型自動車ほどの重さがあります。全ての海洋に生息し、極地の餌場と熱帯の繁殖地の間を回遊します。1日最大4トンのオキアミを摂取する濾過摂食者です。20世紀の捕鯨による絶滅危機からの回復後、世界的な個体数は10,000〜25,000頭と推定される絶滅危惧種です。

Ojiro-ei

The coachwhip ray, Urogymnus granulatus, is a large elasmobranch in the family Urogymidae found across the Indo-Pacific region, ranging from the Red Sea and East Africa through South and Southeast Asia to northern Australia and the western Pacific islands. It inhabits shallow coastal waters including coral reef flats, sandy lagoons, seagrass beds, and estuarine habitats, where it forages for benthic invertebrates and small fishes buried in the substrate. The coachwhip ray is characterized by an oval disc and a long, whip-like tail with one or more venomous spines at its base, giving the species its common name. The disc reaches up to 1.4 meters in width, making it one of the larger members of its family. Urogymnus granulatus is ovoviviparous, giving birth to live young after internal development, and has low reproductive rates that make populations slow to recover from exploitation. The species is classified as Vulnerable by the IUCN due to significant declines caused by intensive coastal fisheries across its range, particularly in South and Southeast Asia where it is commonly caught as bycatch or targeted for its valuable meat, skin, and gill plates in local markets. Habitat degradation from coastal development and coral reef decline compounds the threat to wild populations.