EVERYDAY SCIENCE

Detailed explanation-1: -Sponges were among the earliest animals. While chemical compounds from sponges are preserved in rocks as old as 700 million years, molecular evidence points to sponges developing even earlier. Oxygen levels in the ocean were still low compared to today, but sponges are able to tolerate conditions of low oxygen.

Detailed explanation-2: -The ancient sponge appeared about 2.5 billion years ago-the first animal. Coming in many sizes and shapes, sponge bodies are a loose assemblage of cells held together by a special protein called collagen which is present in all animals.

Detailed explanation-3: -Prevailing theories suggest that sponges are early animals which produced no subsequent evolutionary line. The folks over at Scientific American note that sponges’ specialized cells differentiate them from multicellular protists, creatures which are not animals, plants, or fungus, and which form no tissues.

Detailed explanation-4: -In 2009 researchers discovered fossil fat molecules, presumably originating from sea-sponges, in rocks 645 million years old. Sponges belong to the oldest and most simple animals that had evolved, and their discovery in such old rocks meant that they may have been the first animals.

Detailed explanation-5: -Scientists debate when sponges, animals belonging to the phylum Porifera, first emerged. Some think it wasn’t until the Cambrian period, between 541 million and 485 million years ago, whereas others put it as early as 760 million years ago, during Precambrian times.