Evolutionary origins of hydrothermal vents metazoans

Sarah Samadi

doi:10.1051/bioconf/20150400007

Abstract

The discovery of the oases associated with hydrothermal vents in the deep sea, is probably the most fascinating discovery of oceanography of the last century. In this habitat, contrary to all expectations, a thriving development of unknown organisms was observed. At that time the knowledge about the deep sea organisms was very scarce and the accepted hypotheses about their evolutionary origins, their physiology or their ecology were very speculative. Almost forty years later, exploration of the deep-sea realm, but also of paleontological data together with the improvements in the phylogenetic methods, allowed the rejection of the hypothesis of an evolutionary history cut off the rest of the marine realm. 1. Life in the deep sea: Knowledge is recent Inthe thirtyyears after the discovery of the deep-sea oases associated with hot vents much of the research efforts of the marine biologists have been devoted to this exceptional environment and its inhabitants. However, when the hot vents have been discovered, the deep-sea realm was still poorly known. At this time, most of the available hypotheses about the functioning of deep sea ecosystems, or about the physiology or the evolutionary origins of the organisms were very speculative. In this historical context, I selected three hypotheses which I feel have played a major role in the analysis of the diversity of hot vents' organisms and their evolutionary origins.

Highlights

The discovery of the oases associated with hydrothermal vents in the deep sea, is probably the most fascinating discovery of oceanography of the last century
In the thirty years after the discovery of the deep-sea oases associated with hot vents much of the research efforts of the marine biologists have been devoted to this exceptional environment and its inhabitants
Based on the classification of the newly described species into higher rank categories, Thompson [3] suggested that the abyssal organisms must have an evolutionary origin in the shallow fauna: “It seems probable for several reasons, the most obvious of these being that no Classes nor Orders, and but few Families and Genera, are met with in the abyssal regions which do not likewise occur in shallower water, that the original direction of the migration of marine animals is from the shore seawards”

Summary

Life in the deep sea Knowledge is recent

In the thirty years after the discovery of the deep-sea oases associated with hot vents much of the research efforts of the marine biologists have been devoted to this exceptional environment and its inhabitants. When the hot vents have been discovered, the deep-sea realm was still poorly known At this time, most of the available hypotheses about the functioning of deep sea ecosystems, or about the physiology or the evolutionary origins of the organisms were very speculative. Most of the available hypotheses about the functioning of deep sea ecosystems, or about the physiology or the evolutionary origins of the organisms were very speculative In this historical context, I selected three hypotheses which I feel have played a major role in the analysis of the diversity of hot vents’ organisms and their evolutionary origins. The sampling of all kinds of animals at every explored depth worldwide provided robust grounds to reject the azoic hypothesis This accumulation of facts provided new hypotheses both about the evolutionary origins of the organisms and about the functioning of ecosystems. This hypothesis derives from the lower abundances of deep-sea animals observed at deeper sites and on the absence of light and of living plants and the presence of plant remains on which animal were observed to feed on

Antiquity of deep-sea fauna

Discovery of deep-sea oases associated with hot vents

Conclusions and perspectives