Spotted ratfish
The spotted ratfish, Hydrolagus colliei, is a chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes...

 found in the north-eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

. Often seen by divers at night in the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...

, this harmless shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....

 relative gets its characteristic name from a pointed rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

-like tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...

. The ratfish lays leathery egg cases on the bottom of muddy or sandy areas which are often mistaken by divers as something inanimate. While mainly a deep-water species, it occurs at shallower depths in the northern part of its range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

. The generic name, Hydrolagus, comes from the Greek words "hydro", meaning water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

, and "lagus", meaning hare
Hares and jackrabbits are leporids belonging to the genus Lepus. Hares less than one year old are called leverets. Four species commonly known as types of hare are classified outside of Lepus: the hispid hare , and three species known as red rock hares .Hares are very fast-moving...

, and the specific name honors Alexander Collie
Alexander Collie
Dr Alexander Collie was a Scottish surgeon and botanist who journeyed to Western Australia in 1829, where he was an explorer and Colonial Surgeon.-Early life:...

, who was a ship surgeon and early naturalist. The ratfish is not typically eaten by humans and is not commercially caught.

Physical description

The spotted ratfish has a very distinct appearance compared to unrelated fish species. The female is up to 38 inches (96.5 cm) long, much bigger than the male. These fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 have a smooth and scaless skin that is a silvery-bronze color, often with sparkling shades of gold, blue, and green. The speckled white spots along their back contribute to their name. Dark edges outline both the caudal and dorsal fins, whereas, the pectoral fins have a transparent outline. The ratfish’s pectoral fins are large and triangular, and extend straight out from the sides of their bodies like airplane wings. They have a venomous spine located at the leading edge of their dorsal fin. The tail of the ratfish constitutes almost half of their overall length and closely resembles a pointed rat-like tail. The body of this fish is supported by cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 rather than bone. It has a duckbill shaped snout and a rabbit-like face. The mouth is small and contains forward directed, incisor-shaped teeth, that act as plate-like grinding teeth. One of their most mesmerizing features is their large emerald green eyes which are able to reflect light, similar to eyes of a cat.


The spotted ratfish can be found in the north-eastern Pacific Ocean. They can most commonly be found between the Pacific Northwest. The range of depths in which this fish is found extends from 0 to 3000 ft (0 to 914.4 m) below sea level. Further north the spotted ratfish lives close to the shore. On the southern end of their range, they live in deeper waters. Ratfish tend to move closer to shallow water during the spring and autumn, then to deeper water in summer and winter. Spotted ratfish can most commonly be found living near the bottom of sand, mud or rocky reefs of the ocean floor. Unlike most of its relatives
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes...

 which are entirely restricted to deep waters, the spotted ratfish has been held in public aquaria.


The spotted ratfish swims slowly above the seafloor in search for food. Location of food is done by smell. Their usual hunting period is at nighttime, when they move to shallow water to feed. Spotted ratfish are particularly drawn to crunchy foods like crabs and clams
CLaMS is a modular chemistry transport model system developed at Forschungszentrum Jülich, Germany. CLaMS was first described by McKenna et al. and was expanded into three dimensions by Konopka et al....

. Besides crabs and clams, the spotted ratfish also feeds on shrimp, worms, small fish, small crustaceans, and sea stars. Species known to predate on the spotted ratfish include soupfin sharks
School shark
The school shark, tope shark, soupfin shark or snapper shark, Galeorhinus galeus, is a hound shark of the family Triakidae, the only member of the genus Galeorhinus, found worldwide in subtropical seas at depths of up to...

, dogfish sharks, Pacific halibut
Pacific halibut
The Pacific halibut is found on the continental shelf of the North Pacific Ocean and Bering sea. They are demersal, living on or near the bottom. The halibut is among the largest teleost fish in the world. Halibut are strong swimmers and are able to migrate long distances...

, and Pigeon guillemot
Pigeon Guillemot
The Pigeon Guillemot is a medium-sized alcid endemic to the Pacific. They closely resemble the other members of the genus Cepphus, particularly the Black Guillemot, which is slightly smaller....



Like some sharks, spotted ratfish are oviparous. Their spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 season peaks during the spring to autumn months. During this time, the female releases up to two fertilized eggs into sand or mud areas of the seabed every 10 to 14 days. The extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile. A material is pushed or drawn through a die of the desired cross-section...

 process can last anywhere from 18 to 30 hours and the actual laying can last another four to six days. The egg sack is leather-like, five inches long, and has a filament connected to it which is used to attach it to the ocean floor when it is let go by the mother. It is not unheard of to see a female ratfish swimming around her newly laid eggs, in hopes of preventing predators from finding them. Development of the egg can take up to a year, which can be dangerous because the eggs are sometimes mistaken for inanimate objects by divers. When the young finally hatch, they are about 5.5 inches (14 cm) in length and grow, reaching 11.8 inches (30 cm) in length their first year.


Ratfish around prefers to maintain a safe distance from divers, and are usually not aggressive. However, if they feel their territory has been invaded, the ratfish is able to inflict a mildly toxic wound. As they swim, the ratfish perform barrel roll
Barrel roll
A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on its longitudinal axis while following a helical path, approximately maintaining its original direction. It is sometimes described as "a combination of a loop and a roll"...

s and corkscrew turns, as if they are flying.

Albino Puget Sound ratfish

A rare albino Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...

 ratfish was discovered near Whidbey Island
Whidbey Island
Whidbey Island is one of nine islands located in Island County, Washington, in the United States. Whidbey is located about north of Seattle, and lies between the Olympic Peninsula and the I-5 corridor of western Washington...

, Washington. It is the only pure albino among the 7.2 million specimens in the University of Washington
University of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...

's fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...


External links

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