How do echinoderms and chordates differ developmentally from all the other annua

Question

How do echinoderms and chordates differ developmentally from all the other annual phyla we've looked at this semester? What trait distinguishes chordates from any other phylum? Nematodes and annelids are both commonly referred to as "worms" Mow could you quickly tell whether an organism nematode or an annelid? Compare the feeding mechanisms of the classes of Mollusca. The class Insecta within the Arthropods phylum is hugely diverse. What may have caused this huge burst of diver group? Arthropod body types vary in the number of segments. Which groups that we looked at last week have the most Which have the least? Which phylum or class from last week do you consider to be the most interesting and why? Cite specific ecological traits that you learned from last week, not from common knowledge.

Explanation / Answer

1.Echinoderms and chordates have different types of symmetry, one of their most obvious differences. Chordates like humans have bilateral symmetry, which means you can divide them into a left and right half, and that they have a defined top, bottom, front and back. Echinoderms have radial symmetry, which means you can divide them in various cuts along the center and get equivalent shapes, and have only a defined top and bottom. It can help to visualize the difference if you consider that hotdogs in a bun have bilateral symmetry, while hamburgers have radial symmetry.

2.Chordates have notochord.

3.Nematodes have no segmentation where as annelids have segmentation.

4.Molluscs have a variety of different feeding mechanisms. The bivalve molluscs can filter-feed fine particles form the water. Some of the single-shelled molluscs (limpets) possess a ribbon-shaped tongue or radula, covered with rasping teeth, which enables the animal to scrape algae from the rock. Whelks have a radula on a stalk that can extend beyond the shell and be used to bore into the shells of other molluscs. Through these holes that they have bored they poke the tip of the radula and suck out the flesh of the victim. The cone-shells also have a stalked radula which is modified into type of harpoon with which they secure their prey before injecting it with poison. In still more active carnivores the heavy shell is reduced in size and may even be lost as has occurred in the sea-slugs which have an upper surface covered with tentacles. One species of sea-slug actively hunts jelly fish and ingests these animals stinging cells which it then concentrates in the tentacles and uses them for protection.

5.A Versatile Exoskeleton, segmentation and Appendages Provides More Efficient Locomotion,Air Piped Directly To Cells,Highly Developed Sensory Organs,Less Competition Through Morphosis etc. are the few common features which make insecta the most diverse group.

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