Japanese Eagle Ray

Fascinating facts about the Japanese Eagle Ray

• A ray that can span a disc wider than a typical car door – up to 114 cm across – and reach a total length of 150 cm, the Japanese eagle ray moves through the water with a broad, yellow-brown wing-shaped body dotted with darker spots. Its long stinging spines and tiny claspers (under one-tenth the disc width) hint at a mix of defense and subtle breeding tools.
• While most rays glide over sand, this species lives on the sea floor, hunting crustaceans, fish and even occasional benthic plants. Its diet shows a versatile palate for a bottom-dwelling predator, turning the ocean’s understory into a buffet.
• Like all mylobatids, the Japanese eagle ray gives birth to live young that first live off yolk and later sip uterine fluid from their mother, a hidden nourishment system that keeps embryos safe until they hatch fully formed.
• Found from the coasts of Japan, Korea and China down to Indonesia and the Philippines, it prefers tropical waters deeper than 220 m. Though sometimes caught as bycatch or for meat and cartilage, no specific protections exist, and the IUCN currently lists it as Vulnerable, signaling a need for attention.
• Even its parasites are named after it: Caulobothrium tobijei, Raphidascaroides myliobatum, and Mawsonascaris myliobatum all make the Japanese eagle ray their host, highlighting a specialized ecological relationship that scientists are only beginning to map.

At a glance

About the Japanese Eagle Ray

The Japanese eagle ray, Myliobatis tobijei, glides through the deep tropical waters of East Asia with a disc that can span at least 114 cm and a total length of up to 150 cm. Its yellow-brown skin is peppered with darker spots, a camouflage that blends with the muted seafloor. Long, slender stinging spines line its tail, while the male’s claspers are strikingly short, less than one-tenth the disc’s width. Each jaw houses seven rows of teeth, a dental arsenal that lets the ray crush crustaceans and small fish, and even nibble on benthic plants when the opportunity arises. A demersal specialist, this ray dwells on sea floors deeper than 220 m, hunting benthic animals that scuttle across the substrate. Like its mylobatid relatives, it is ovoviviparous: embryos first rely on yolk, then absorb uterine fluid from the mother, a subtle form of nourishment that bypasses a placental connection. Though little else is known about its biology, the combination of a broad disc, vivid coloration, and the surprising fact that its claspers are proportionally tiny for a ray of its size makes the Japanese eagle ray a striking, yet enigmatic, inhabitant of the Indo-Pacific deep.

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