In this article we will discuss about Water Vascular System of Echinoderms:- 1. Introduction to Water Vascular System 2. Contents of Water Vascular System 3. General Plan 4. Modifications 5. Functions. Introduction to Water Vascular System: The water vascular system is enterocoelic in origin and arises from the left hydrocoel. It exhibits radial symmetry from the beginning and is equally [...]
Larva Found in Phylum Echinodermata! 1. Dipleurula Larva: 1. The dipleurula form (Fig. 21.39A) is reached during development and is characterised by its bilaterally symmetrical, egg-shaped body. 2. The ventral concave side bears the mouth and is encircled by a circumoral ciliated band. 3. The anus is disposed ventrally. 4. The digestive canal is differentiated into oesophagus, stomach and intestine. [...]
In this article we will discuss about the development characteristics of protostomes and deuterostomes. Protostomes: Developmental Characteristics: 1. Pattern of embryonic cleavage: Spiral cleavage pattern; the spiral cleavage is masked at the 6th cleavages (64-cell stage), e.g., Sipuncula, Echiura, Annelida, Pogonophora, Mollusca and some groups of Arthropoda (e.g., Myriapoda, Crustacea and Insecta except Chelicerata). 2. Fate of embryonic blastomeres: Determinate [...]