AP BIOLOGY

Detailed explanation-1: -Recent genomic studies have suggested that comb jellies, members of the phylum Ctenophora, are the sister group to all animals but now new research, led by the University of Bristol, reaffirms the traditional view – that sponges (Porifera) are the oldest animal phylum.

Detailed explanation-2: -Porifera Phylogeny The group of organisms known as sponges (Porifera) is considered the earliest branching group of Metazoans, or animals, with fossils described from the Vendian Period, dating back 650-543 million years ago (Porifera: Systematics, 2006).

Detailed explanation-3: -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.

Detailed explanation-4: -Relatives of the humble sea sponge have filtered Earth’s waters for hundreds of millions of years or more, long before the first plants took to land. Their simplicity has led scientists to suggest sponges were the earliest animals to arise on our planet.

Detailed explanation-5: -Sponges lack these characters and have generally been considered the most basal metazoan group; fossil evidence for sponges also long predates the earliest clear ctenophore, cnidarian or bilaterian remains.