Mysterious fish: the chimera

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There are, in the depths of the oceans, many mysterious and unknown animals, like the chimera.

The chimera is different in many ways from other fish. This strange animal is scattered all over the world, between 100 and 1700 meters deep. In summer, it sometimes rises to the surface but, in winter, it seeks the depths, where the temperature variations are less important.

Its appearance is quite appealing because it has large eyes, a head more prominent than the rest of the body and a fairly long caudal fin. Since it can measure between one and two meters, it has been given the term “underwater monster”.


These strange animals are part of the group of chimeriforms, an order of cartilaginous fish. Their skulls differentiate them from the rest of the abyssal fish, which explains why they constitute a particular subclass: that of the holocephali. In this subclass, chimeras are accompanied by other fishes known as ”  ghost sharks “.

Today, only 47 species of chimeriforms survive.

Characteristics of chimeras

As we have already commented, its aspect is extremely curious:

  • At first, they have a large protruding head. We detect a grotesque face due to the appearance given to it by the two mucous channels. Their upper mandible blends into the rest of the skull
  • Secondly, they have a long spindle-shaped tail, typical of many deep -sea fish.
  • Thirdly, their eyes are phosphorescent green, full of photoreceptors to optimize their vision in the depths
A chimera at the bottom of the sea

Monstrous chimera. By Andy Murch – ELASMODIVER

These characteristics are those which gave it the name of “chimera”, a term which recalls the monsters of Greek mythology made up of parts of different animals.

They can measure up to two meters, the largest part being that of their disproportionate tail. Females are also larger than males. They have a body devoid of scales, compressed laterally, developed lengthwise and very thin towards the tail.

Their skeleton is cartilaginous, like that of the elasmobranchs – sharks and rays. However, it only consists of two gill openings, which brings them closer to bony fish.

The chimeras have the same skeleton as the rays

Another of their most striking features is the tip it has on the front of the spine. They can, with it, cause deep wounds and even inoculate poison with their predators .

Their bite is very painful; despite everything, it is not fatal for humans, unless they are allergic to it.


The chimeras feed on molluscs and other small animals on the seabed, such as crabs , shrimps or starfish.  They have teeth which are real crushers.

Reproduction of the chimera

Chimeras have pterygopods which act as male external sexual organs. And, sometimes, they have a small “pseudo-pterygopod” on the head, like some prehistoric sharks.

The males take advantage of this fleshy protuberance that they have between the eyes to hold the females during copulation.

The female lays her eggs and buries them in the sand. Each egg remains enclosed in a horny capsule and lined with hair.

Chimaera monstrosa  : the monstrous chimera of our seas

It is a species of chimera typical of the northwest of the Atlantic Ocean and the Mediterranean Sea. It seems to prefer the upper continental platform, between 300 and 500 meters deep.

In the Mediterranean Sea, this species is found from 100 meters deep but is more abundant between 500 and 800 meters. Specimens have been identified 650 meters deep in the Balearic Sea, and 800 meters deep in the Ionian Sea.