The following points highlight the twelve main features of Phylum Placozoa. 1. Phylum Placozoa are minute, shapeless, multicellular mobile flattend animals. 2. 2-3 mm in diameter. 3. Body of Phylum Placozoa is composed of two outer layers with monociliated epithelial cells. 4. Epithelial cells lack a basal lamina. 5. An inner layer containing loose contractile columnar cells with a single [...]
The following points highlight the three main types of canal system encountered in sponges. The types are: 1. Ascon Type 2. Sycon Type 3. Leucon Type and 4. Rhagon Type. 1. Asconoid Type: The asconoid type of canal system is regarded to be the most simple and primitive grade of canal system. Asconoid type is present in these sponges whose [...]
Master Notes on Cnidarians:- 1. Protohydra 2. Halistemma 3. Physalia 4. Porpita 5. Velella 6. Diphyes. Cnidarian # 1. Protohydra: Protohydra (Fig. 12.29A) is a peculiar hydra of 3 mm in length. It lacks the usual tentacles. It is available along the shores of Great Britain and northern part of Europe. Protohydra feeds on nematodes and small crustaceans and propagates [...]