Spotted Ratfish | Oceana
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Ocean Fishes

Spotted Ratfish

Hydrolagus colliei

Distribution

Subtropical to sub-polar latitudes of the northeast Pacific Ocean

Ecosystem/Habitat

Soft bottoms

Feeding Habits

Foraging predator

Conservation Status

Least Concern

Taxonomy

Order Chimaeriformes (chimaeras), Family Chimaeridae (shortnose chimaeras)

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The spotted ratfish is one of 36 species of shortnose chimaeras, a group of fishes closely related to the sharks and rays. It gets its common name from its long, thin tail that early scientists thought resembled a rat’s. This species spends most of its time at or near the seafloor and is typically restricted to depths below 330 feet (100 m) but can be observed at much shallower depths at night and has been known to approach SCUBA divers diving after dark.

Like sharks and rays, the chimaeras have skeletons made of cartilage rather than bone.  This characteristic links those three groups of fishes and distinguishes them from the bony fishes.  The spotted ratfish is a generalist predator and eats a variety of invertebrates and fishes associated with the sea floor.  These include crabs, clams, and other hard-shelled prey, and the spotted ratfish has strong tooth plates, used to break apart these animals.  Medium sized sharks and large bony fishes (e.g., the Pacific halibut) have been known to eat this species.

Spotted ratfish reproduce via internal fertilization, and the males have two large, forked claspers, which they use to pass sperm to females.  They also have a unique head clasper, the purpose of which is not well known, but that may be used to corral a female during courtship.  Females lay strong egg cases, made of keratin.  Eggs take several months to mature, and they receive no care or protection from their parents after they are deposited on the seafloor.  When a single juvenile hatches from the egg case, it is ready to begin a predatory lifestyle.  Its prey generally grows in size as it matures.

This species is not fished commercially or for recreation, but it is occasionally captured accidentally in fisheries targeting other species.  Scientists believe the populations to be stable, and the spotted ratfish is a species of least concern.  

 

Additional Resources:

http://www.iucnredlist.org/details/60191/0

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