EVERYDAY SCIENCE

Detailed explanation-1: -The phylum Porifera comprises the sponges. Sponges are simple invertebrate animals that live in aquatic habitats. Although the majority of sponges are marine, some species live in freshwater lakes and streams. They are found in shallow ocean environments to depths as great as five kilometers (km).

Detailed explanation-2: -Introduction to Porifera. Poriferans are commonly referred to as sponges. An early branching event in the history of animals separated the sponges from other metazoans. As one would expect based on their phylogenetic position, fossil sponges are among the oldest known animal fossils, dating from the Late Precambrian.

Detailed explanation-3: -The correct answer is Porifera. Members of the phylum Porifera are known as sponges.

Detailed explanation-4: -Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs. Some of them are radially symmetrical, but most are asymmetrical.

Detailed explanation-5: -The three classes are: 1. Calcarea or Calcispongiae-(Calcareous Sponges) 2. Hexactinellida or Triaxonida or Hyalospongiae-(Glass Sponge) 3. Demospongiae.