Answer to Question #267700 in Zoology for Jess

Question

1. From very simple animals like sponges to very complex animals like Vertebrates, the phylogeny tree shows the more characteristics /features an animal has, the more complex it becomes.

In your essay, use examples to explain the significance of the following features in the evolution of the Animal Kingdom.

i. Development of a coelom

ii. Bilateral symmetry and cephalization

iii. Segmentation 

Answer 1

Development. Coelom is the mesodermally lined cavity between the gut and the outer body wall. During the development of the embryo, coelom formation begins in the gastrulation stage. The archenteron wall produces buds of mesoderm, and these mesodermal diverticula hollow to become the coelomic cavities.

Cephalization is defined as the evolutionary trend toward nervous system centralization and the development of a head and brain. Cephalized organisms display bilateral symmetry. Sense organs or tissues are concentrated on or near the head, which is at the front of the animal as it moves forward