Fish
Spotted Ratfish
Hydrolagus colliei · also called spotted rat fish
Rising from deeper water into shallow coastal bays after dark, a spotted ratfish reveals large, green-glowing eyes built for gathering faint light, a smooth-skinned chimaera whose long, tapering tail gave the species its common name.
Overview
The spotted ratfish, Hydrolagus colliei, is a chimaera native to coastal and ocean habitat along the Pacific coast of North America. Its brightly reflective, glowing green eyes, distinctive spotted pattern and rat-like tail, and daily migration between shallow and deep water make it one of the more visually memorable cartilaginous fish found along the region’s coastline.
A creature of the changing tide of depth
Unlike many of its deeper-living chimaera relatives, the spotted ratfish regularly moves into shallow coastal water after dark, giving divers and researchers a rare close look at a group of cartilaginous fish more typically confined to depths humans never see.
Status
Least Concern, remaining widespread and stable across suitable coastal and ocean habitat along the Pacific coast of North America.
Spotted Ratfish: common questions
Why do the spotted ratfish's eyes appear to glow?
This species has large eyes with a strongly reflective layer behind the retina, causing them to appear to glow bright green when lit by a torch or camera flash, an adaptation that helps the species gather what little light is available in dark water.
Why is it called the spotted ratfish?
This species has a long, thin, tapering, rat-like tail combined with a spotted body pattern, a combination distinctive enough to give the species its common name.
Does the spotted ratfish stay at the same depth all the time?
No, this species is often found in much shallower coastal water at night than during the day, when it typically retreats to deeper water along the continental shelf.
What is the structure on top of a male spotted ratfish's head?
Males of this species have a small, retractable clasping organ on the top of the head, used to grip the female during mating, a feature unique to chimaeras among cartilaginous fish.