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Echinoderms from Venezuela: Scientific recount, diversity and distribution

Abstract:

This chapter presents a historical review of the study on living and fossil species of the Phylum Echinodermata of Venezuela; most of the research has been carried out in the middle-western and eastern coasts of the country. There is currently a total of 234 species of echinoderms known from Venezuelan waters, with 97.87 % of them from the Caribbean coasts and only 2.13 % from the Atlantic coast. The following species have only been reported in the latter zone, Tethyaster vestitus (Asteroidea), Leptopentacta deichmannae (Holothuroidea), Paraster doederleini (Echinoidea) and Amphiura otteri (Ophiuroidea). The Class Asteroidea is the most diverse with 63 species (26.92 %), 40 genera, 15 families and six orders, followed by Holothuroidea with 53 species (22.65 %), 34 genera, 12 families and two orders. The Class Ophiuroidea has 52 species, 31 genera, 14 families and two orders; Echinoidea has 50 species (21.38 %), 38 genera, 22 families and ten orders, and Crinoidea with 16 species (6.84 %), 15 genera, nine families and four orders. There are fossil echinoderms in the sedimentary basin of Venezuela and their potential use as paleoecological indicators complement stratigraphic studies. Most of the recent reports of echinoderms in Venezuela are from depths between 0 and 50 m (47.42 %), followed by the depth ranges 51-199 m (26.12 %), 200-499 m (8.25 %) and more than 500 m (18.21 %). Considering the distribution of the echinoderms along the described ecoregions for the coasts of Venezuela, 29.17 % of the known species are recorded from the Eastern Upwelling ecoregion, followed by the Oceanic Islands (23.33 %) and the Central Coast (10.42 %). The lowest presence was found in the ecoregion of the Gulf of Venezuela (1.67 %). No echinoderms have been reported from Lake Maracaibo, most likely due to the low salinity of its water. Although there is no strong tradition for the consumption of echinoderms in the country, the threat of an irrational exploitation of these resources still exists, due to the increased demand of the Asian markets, the absence of evaluations of the current echinoderm populations and the lack of official norms and control for their extraction and/or commercialization. The species that has received the most attention for culturing is the sea urchin, Lytechinus variegatus, which has been used for experiments on mass production of larvae, postlarvae and juveniles. In spite of the effort allocated in the current study to identify the different echinoderm classes, families and species found in the ecoregions of Venezuela, more detailed spatial analyses should be made on the echinoderm distribution along the entire Venezuelan coast line. Such studies should generate information about their density and other population parameters, including growth, reproduction, feeding, and their relation with the surrounding biotic and abiotic parameters, as well as the evaluation of the environmental factors that influence their presence in a particular area.