Subterranean Fishes of the World

6448

2024

Fishes

1-34

9, 243

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/ 4.0/)

Abstract: Fishes in marine caves have attracted limited attention by the scientific community in comparison to subterranean fishes which have lost eyes and pigmentation. They constitute a largely unexplored component of marine fish diversity, except for the relatively well-studied marine caves of the Mediterranean Sea. These habitats are characterized by steep environmental gradients of decreasing light and decreasing water exchange. The fishes recorded so far in marine caves are not exclusive residents of this habitat and they are also present at least in the other mesolithial habitats. In the Mediterranean marine caves, 132 fishes have been recorded to date, representing about 17% of the total Mediterranean fish species richness. Most of these species are reported from the anterior cave zones where some light still exists, while a smaller number of species are known from the totally dark zones. Among them, 27.3% are accidental visitors, 53.8% are the regular mesolithial visitors and switchers between mesolithion and open water, 5.3% are permanent residents of the mesolithion, but also occur in other habitats, and 13.6% are exclusive permanent residents of mesolithion. Some mesolithial exclusive permanent residents recorded in marine caves share similar morphology, probably as adaptations to these habitats. Keywords: fishes; marine caves; mesolithion; ecology; adaptation; diversity; distribution Key Contribution: Marine caves are part of mesolithial habitats, together with pseudocaves and cryptobenthic habitats. Fishes recorded in marine caves are not exclusive cave residents. Five different morphological types of fish can be identified in relation to their adaptation to mesolithial habitats.

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