Rhinochimaera costaricana, a long-nosed chimaera documented off Costa Rica.Species illustration

A ghost shark emerges from the deep

Scientists have formally described a remarkable long-nosed chimaera from the eastern Pacific—revealing another branch of life in waters we are only beginning to understand.

RoarSoar Ocean Desk
6 September 2026 · 5 minute read · Sources shown below

In the dim Pacific waters off Costa Rica lives a fish unlike the familiar sharks and rays of shallow seas. Its elongated snout, tall dorsal spine and tapering body place it among the long-nosed chimaeras—ancient cartilaginous fishes commonly known as “ghost sharks.”

In 2026, researchers formally named the species Rhinochimaera costaricana. The description was based on three male specimens collected off Costa Rica between 2000 and 2023 at depths of 390 to 787 metres. Together, they provided enough anatomical and genetic evidence to distinguish this animal from the three other recognised species in its genus.

What the researchers examined
Forty-nine body measurements from the three specimens were compared with published and unpublished information from 90 additional Rhinochimaera specimens. Molecular evidence supported the anatomical differences.

Not a shark, but a distant relative

The nickname “ghost shark” is evocative, but chimaeras are not true sharks. They belong to Holocephali, a distinct branch of cartilaginous fishes related to sharks and rays. Their unusual forms reflect a long evolutionary history—and their deep habitats make them difficult to encounter and study.

Why a scientific name matters

Naming a species is more than attaching a label. A formal description gives scientists a shared reference for future records, ecological research and conservation assessments. Without that foundation, observations from separate voyages can remain disconnected—or be mistaken for a better-known relative.

The new species is distinguished by a combination of characteristics including a shorter snout, a larger and taller first dorsal-fin spine, a higher first dorsal fin, wider spacing between dorsal fins and fewer tail tubercles. Its formal description also makes it the first recognised member of Rhinochimaera from the eastern Pacific.

“Every well-documented species enlarges the map of life—and shows us how much of that map remains unfinished.”

A discovery assembled across decades

The collection dates tell another important story. Scientific discovery does not always happen at the moment an animal is first brought to the surface. Specimens preserved in research collections can wait years before improved comparisons, collaboration and genetic techniques reveal what they represent.

This case links specimens gathered across more than two decades. It demonstrates why biological collections, careful field records and long-term scientific cooperation matter: together, they allow researchers to revisit the unknown with better questions and better tools.

Continue with the evidence

RoarSoar has summarised the published research in original language. The scientific paper remains the authoritative source. This developing article welcomes corrections, additional research and properly credited field material.