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Rabbit fish

life science Maturity 5-7 Next article →

The rabbit fish, known scientifically as Chimaera monstrosa, is a unique type of cartilaginous fish. This means its skeleton is made of cartilage rather than hard bone. It belongs to the Chimaeridae family and is a distant relative of sharks.

Chimaera monstrosa3
Chimaera monstrosa3

People often call it the rabbit fish or rat fish because of its appearance. It has a very large head and a small, tapering body. Its large eyes, nostrils, and tooth plates give it a look similar to a rabbit. This species is an important part of the marine ecosystems in the northeast Atlantic and the Mediterranean Sea.

Chimaera monstrosa3
Chimaera monstrosa3

The physical structure of the rabbit fish is quite distinct. It has a short snout with an overhanging mouth. A tall, triangular dorsal fin sits high on its spine. This fin features a spine that extends beyond the tip of the fin. This spine runs the length of the fish and joins the caudal fin, which is a whip-like tail. Interestingly, this dorsal spine is mildly poisonous and can cause painful stings. Unlike its close relatives, the rabbit fish has an anal fin that is separate from its lancet-shaped caudal fin. Its skin is silver-green with brown spots and marmor-white stripes.

Growth and life expectancy for this species are quite specific. The rabbit fish is characterized by a slow growth rate and a long life. One study estimated the theoretical asymptotic length to be 78.87 cm. This study also found a yearly growth rate of 6.73%. The age of maturity depends on the sex of the fish. Males reach maturity at 13.4 years, while females reach it at 11.2 years. Males can live for up to 30 years, but females typically live up to 26 years.

Oeuf de chimere 2
Oeuf de chimere 2

These fish are benthophagous, which means they are bottom-feeders. They primarily eat invertebrates found on the seabed, such as crabs, molluscs, octopuses, sea-worms, and sea urchins. However, they are also opportunistic feeders, meaning they change their diet based on what is available. Their diet changes significantly as they grow in size. Smaller specimens mainly eat amphipods. Fish between certain sizes eat both amphipods and decapods. The largest individuals, those over a certain size, have a narrow diet and mainly consume decapods. This ability to change their diet helps them survive in food-restricted deep-water environments.

Oeuf de chimere 2
Oeuf de chimere 2

The habitat of the rabbit fish spans a wide geographic range. They are found from Morocco in the north to Norway and Iceland in the northern North Sea. Most of these fish live on the continental slope at depths between 600 and 1,000 meters. They prefer seabeds made of mud or soft substrate. The deepest they have been reported is 2,000 meters. They typically live in water temperatures ranging from 4 to 12 degrees Celsius. During the spring and summer, they may migrate inshore to shallower depths of 200 meters to lay eggs.

Oeuf de chimere 2
Oeuf de chimere 2

Reproduction in Chimaera monstrosa involves several complex behaviors. The species is oviparous, meaning the embryos develop inside eggs rather than inside the female.

Oeuf de chimere 2
Oeuf de chimere 2

Males have a unique club-like structure on top of their heads. This structure has a bulbous tip with many sharp denticles, or small tooth-like structures. Males use this club to grasp the female's pectoral fin during copulation. There is also sexual segregation based on depth. Females prefer deeper waters of 1,000 meters, but they move up to 200 meters to mate. This separation helps males regulate sperm in warmer, shallower waters.

Oeuf de chimere 2
Oeuf de chimere 2

Currently, the rabbit fish is listed as a vulnerable species on the IUCN Red List. This means they face a high risk of extinction in the wild. One reason for their decline is their value in fisheries. They have high levels of lipids, which are fats. People hunt them to obtain liver oils for making dietary supplements. Additionally, they are often caught as bycatch. Bycatch occurs when fish are caught accidentally in nets intended for other species. Protecting these deep-sea creatures is vital for maintaining the balance of the ocean floor.

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File:Chimaera monstrosa3.jpg
Chimaera monstrosa3.jpg
File:Oeuf de chimere 2.jpg
Oeuf de chimere 2.jpg
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