Biological Development in the Oceans

LIFE IN THE OCEANS BEGINS

The foundation for much of this Biological Development section is Man and the Ocean, a CD-ROM produced by the Russian Head Department of Navigation and Oceanography (HDNO).

The organic kingdom of the Archean contained only micro-organisms, unicellular and not possessing nuclei. Among them were diverse bacteria and primitive algae. They lived not only in top layers of the water, but also in places in the shallow ocean.

 

Development of the Plant and Animal Kingdoms

The Palaeozoic era (570-230 million years ago), is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. In the extensive oceans of this era, the plant and animal kingdoms developed and evolved. Many marine animals already had calcareous or silicic shells and skeletons. In the early Palaeozoic time, the first vertebrate animals evolved. By the middle of the Palaeozoic era, extensive parts of the land-mass had become colonised by plants and various species of fishes developed in the oceans. By the end of the Palaeozoic the first animals - vertebrates - began to leave the sea. These were amphibians. At the time-boundary between the Palaeozoic and Mesozoic, the single continent (land-mass) was split into two "super-continents" - Laurasia in the Northern Hemisphere and Gondwana in the Southern Hemisphere.