Several carapid fishes, known as pearlfishes, are endosymbiotic in holothuroids and asteroids.
2011), but another extraordinary example, though less known, is the symbiosis between carapid fishes (Ophidiiformes) and various invertebrates.
05), but there was between carapid species (P < 0.
A comparison of the histology of gills of untreated and treated fishes showed that the carapid gills were much less altered than those of the other fishes (Figs.
akallopisos) to 16 (in the carapid species) blood vessels flanked by the core of the pillar cells (Fig.
Parmentier and Vandewalle (2005) were the first to test carapid resistance to the presence of Cuvierian tubules.
As the gill structure does not explain the resistance of carapids to saponins, three other hypotheses can be suggested: (i) the quantity of mucus secreted in carapids is higher than in other fishes, and the thickness of the mucus creates a natural barrier against the toxin, (ii) the nature of the mucus in carapids is different from that of other fishes and includes some molecules, such as enzymes, that can act on saponins and suppress their noxious effects, and (iii) saponins cannot act on carapid gills because the cytoplasmic membrane of their epithelial cells possesses special sterols, as is the case for their hosts.