Question

Q.5. Give a brief description of the following pairs of terms: a). Diploblastic vs. Triploblastic b). Choanocyte vs. Choanoflagellate c). Protist vs. Animal d). Acoelomate vs. Pseudocoelomate

Answer 1

a) Diploblastic vs Triploblastic

Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm are called Diploblastic animals. Here there will be the presence of an undifferentiated layer called mesoglea. eg: Coelentrates

Animals in which the developing embryo has a third germinal layer, mesoderm in between ectoderm and endoderm are called Triploblastic aninmals. eg: Platyhelminthes to chordates

b) Choanocyte vs Choanoflagellate

Choanocytes or collar cells are nucleated flagellated cells found in sponges of phylum Porifera. These cells help to maintain a flow of water through the body, so that water can enter through the pores in sponge body and goes out through the oscullum and thus aids in feeding.

Choanoflafellates or collared flagellates are a group of small flagellated eukaryotes which can be found in both freshwater and marine environment. Thay are important cladistically because they seem to be closest living relative to animals. eg: Monosiga brevicollis

c) Protists vs animals

Protists are single celled eukaryotic organisms. They include both autotrophic and heterotrophic organisms. eg: Euglena.

Animals are multicellular, eukaryotic organisms and they are heterotrophic. eg: Human

d) Acoelomate vs Pseudocoelomate

Acoelomates are triploblastic animals lacking a true coelom, which is a fluid filled body cavity formed by the splitting of lateral mesodermal layer during embryonic development. In acoelomates, tissues derived from the mesoderm form a solid mass of cells between the ectoderm and endoderm with out leaving a solid cavity. eg: Platyhelminthes

Pseudocoelomate are triploblastic animals with a false coelom which is not entirly developed from the mesoderm. Here the coelom is formed by the splitting of mesodermal and endodermal cells, and not completely of mesoderm origin.eg: earthworm