The Origin of Diploblastic Organisms

Avonlea Gardner, Stefani Williams, Ben Lawhorn, Max Rossa

Developed Characteristics within

phylum Radiata● Radial morphology

● Diploblastic (two germ layers during development) – ectoderm and endoderm

● Cnidocytes present- housing Nematocyst (Stinging cells)

● Nerve Network

● Extracellular digestion

● Muscular contractions via epitheliomuscular cells○ May provide evidence as the origin of mesoderm in Triploblastic organisms.

● Sexual reproduction and Asexual reproduction ○ First evidence of cleavage in dividing cells

Origins in Respect to Protists

Members of Radiata have a few aspects in common with their more primitive unicellular ancestors, the Protists

● Nematocysts○ Some protists resemble nematocysts, or

stinging cells, which Cnidaria have incorporated into their body plan to aid with protection and hunting prey

● Cilia○ Radiata, and especially Ctenophora, have

incorporated Cilia tracts into their body plan, which aid in locomotion.

A network of nerve cells● Unspecialized● Multifunctional neurons

○ sensory○ motor○ intersecretory○ neurosecratory

Cnidarian’s Nerve Net

● Ureumetazoan- believed to be a common ancestor of cnidarians and bilaterians

● Cnidarians are thought to have originated very far back into the Cryogenian age

● http://www.imas.utas.edu.au/__data/assets/image/0006/271671/ctenophore_a_full.jpg

● http://mageebio11spring2012.wordpress.com/2012/02/22/phylum-cnidaria/

● http://www.sciencemag.org/content/334/6059/1091.full

● http://link.springer.com/chapter/10.1007/978-3-0348-9219-3_2

Resources