Fact of the Day : Which type of fish are also known as ratfish or rabbitfish? (from The Encyclopedia of Underwater Life )It is easy to see how the Ratfish (Chimaera monstrosa) earned its common name.
Chimaeras
A large, blunt head, an erectable spine in front of the first dorsal fin, and a gill cover over the four gills that leaves a single opening are some characteristics of the chimaeras. Named for the she-monster of Greek mythology, which had a lion's head, a goat's body, and a serpent's tail, these unusual relations of the sharks are also known as ratfish or rabbitfish; one of the generic names (Hydrolagus) literally means “water (hydros) rabbit (lagus)”.
It is easy to see how the Ratfish (Chimaera monstrosa) earned its common name. Chimaeras live in cold water, often at great depths – some have been recorded as deep as 2,400m (8,000ft). They are poor swimmers. Instead of using powerful side-to-side body movements like most fishes, especially sharks, they swim by flapping their pectoral fins, which makes them bob up and down in a clumsy fashion. Chimaeras usually keep close to the seafloor and have been observed motionless on the bottom, perched on the tips of their fins.
Like all cartilaginous fishes, the males have pelvic claspers to introduce sperm into the female. However, male chimaeras also have a second pair of retractable claspers in front of the pelvic fins that are probably used to hold the female during mating. Mature males also have a clasper on the forehead. Long-nosed and plow-nosed chimaeras have elongated, fleshy, and flexible head projections (rostra), which are covered with electrical and chemical receptors.
Chimaeras are durophagous – a term meaning that they habitually feed on items that are hard. Their teeth are fused together to form three crushing plates, one in the lower jaw and two in the upper jaw, which are used to crush the shells of their food, mollusks, crustaceans, and a few small fishes. Their large eyes are adaptations to low ambient light.
Young chimaeras are covered by short, stout dermal denticles (minute teeth), which are lost as they mature, except in long-nosed chimaeras, which keep some of them for life. All chimaeras lay fairly large eggs, 15–25cm (6–10in) with a hard leathery shell that hatch in 6–8 months.
Most sharks take in water through the mouth to pass over the gills but chimaeras take in water through large nostrils connected to special channels, which direct the water to the gills. Unlike sharks, chimaeras have their gills in a common chamber protected by a flap (operculum).
The flesh of chimaeras is eaten mostly in Australia, New Zealand, and China, although the fillets are best pre-soaked in freshwater to remove the slight taste of ammonia. In the past, chimaera liver was used as a source of machine oil.
Jack Jackson / Andrew Campbell
How to cite this entry:
Jack Jackson , Andrew Campbell "Chimaeras" The Encyclopedia of Underwater Life. Ed. Andrew Campbell & John Dawes. Oxford University Press, 2007. Oxford Reference Online. Oxford University Press. 12 September 2011
A large, blunt head, an erectable spine in front of the first dorsal fin, and a gill cover over the four gills that leaves a single opening are some characteristics of the chimaeras. Named for the she-monster of Greek mythology, which had a lion's head, a goat's body, and a serpent's tail, these unusual relations of the sharks are also known as ratfish or rabbitfish; one of the generic names (Hydrolagus) literally means “water (hydros) rabbit (lagus)”.
It is easy to see how the Ratfish (Chimaera monstrosa) earned its common name. Chimaeras live in cold water, often at great depths – some have been recorded as deep as 2,400m (8,000ft). They are poor swimmers. Instead of using powerful side-to-side body movements like most fishes, especially sharks, they swim by flapping their pectoral fins, which makes them bob up and down in a clumsy fashion. Chimaeras usually keep close to the seafloor and have been observed motionless on the bottom, perched on the tips of their fins.
Like all cartilaginous fishes, the males have pelvic claspers to introduce sperm into the female. However, male chimaeras also have a second pair of retractable claspers in front of the pelvic fins that are probably used to hold the female during mating. Mature males also have a clasper on the forehead. Long-nosed and plow-nosed chimaeras have elongated, fleshy, and flexible head projections (rostra), which are covered with electrical and chemical receptors.
Chimaeras are durophagous – a term meaning that they habitually feed on items that are hard. Their teeth are fused together to form three crushing plates, one in the lower jaw and two in the upper jaw, which are used to crush the shells of their food, mollusks, crustaceans, and a few small fishes. Their large eyes are adaptations to low ambient light.
Young chimaeras are covered by short, stout dermal denticles (minute teeth), which are lost as they mature, except in long-nosed chimaeras, which keep some of them for life. All chimaeras lay fairly large eggs, 15–25cm (6–10in) with a hard leathery shell that hatch in 6–8 months.
Most sharks take in water through the mouth to pass over the gills but chimaeras take in water through large nostrils connected to special channels, which direct the water to the gills. Unlike sharks, chimaeras have their gills in a common chamber protected by a flap (operculum).
The flesh of chimaeras is eaten mostly in Australia, New Zealand, and China, although the fillets are best pre-soaked in freshwater to remove the slight taste of ammonia. In the past, chimaera liver was used as a source of machine oil.
Jack Jackson / Andrew Campbell
How to cite this entry:
Jack Jackson , Andrew Campbell "Chimaeras" The Encyclopedia of Underwater Life. Ed. Andrew Campbell & John Dawes. Oxford University Press, 2007. Oxford Reference Online. Oxford University Press. 12 September 2011
