Читать книгу Clinical Guide to Fish Medicine - Группа авторов - Страница 76

Chimaeriformes have a cartilaginous skeleton like elasmobranchs, but the upper jaw with grinding tooth‐plates is fused to the cranium. There is one gill opening (a small operculum) over the gills; they lack a spiracle except as embryos. The eyes cannot regulate the light going onto their retinas, so exposure to bright lights is a concern. Additionally, a condition termed “bloody eye” has been reported that is a result of handling‐induced damage to the pseudobranchial artery (Tozer and Didier 2004). The skin is scaleless except for denticles over the pelvic claspers and tenaculum (a club‐like clasping organ on the head). The dorsal spine is venomous and can cause moderate discomfort to humans. They lack a stomach, ribs, epigonal and Leydig organs; there is a spiral intestine and a rectal gland. There are separate anal and urogenital openings, unlike the cloaca of elasmobranchs. Males have claspers and fertilization is internal (Honma et al. 1984; Tozer and Didier 2004; Nelson et al. 2016).