chimaeras

Chimaeras, or ghost sharks, are cartilaginous fishes in the order Chimaeriformes, within the subclass Holocephali. They are an ancient lineage related to sharks and rays, but distinct in anatomy and reproductive biology.

Morphology: Chimaeras have a stout body with a large head and long tail. They lack true teeth, instead having dental plates. Their gills are arranged as five pairs of gill slits on each side, usually covered by a soft opercular flap. The mouth is ventral and the pectoral fins are large; males have claspers for internal fertilization.

Distribution and habitat: They occur in temperate and tropical seas worldwide, commonly on continental slopes and in deep-water habitats, from shallow coastal regions to several thousand meters deep.

Ecology and life history: Chimaeras feed on mollusks, crustaceans, and small fish. They are slow-growing with low reproductive output; many species lay eggs in protective capsules attached to the seabed.

Evolution and conservation: The order is an ancient lineage with living species representing early jawed vertebrates. Some species are affected by deep-sea fisheries and habitat disturbance; data on many species remain limited, complicating conservation assessments.