Question

molecular evidence has led taxonomists to group bilaterally symmetrical animals in one of three classes, Deuterostomia, Lophotrochzoa, or Ecdysozoa. Give one distinguishing characteristic of each of these groups other than molecular differences.

Answer 1

Deuterostomia - The Deuterostomia consists one of the major groups within the animal kingdom. They belong to the subkingdom Eumetazoa. It is differentiated from protosomes by development of embryo. The first opening in this clade is anus. They have coelom developed through anterocoely. They include echinoderms and the chordates.

Lophotrochozoa – They are a clade of protostome animals within the Spiralia. The taxon is established as a monophyletic group, which is based on molecular evidence. They have trochopore larvae and a feeding structure known as lophopore. Every member of this group is triploblastic and bilateral symmetrical. They have the ability to shed their exoskeleton many a times in its life span.

Ecdysozoa - It is a group of protostome animals, which includes Arthropoda, Nematoda and several smaller phyla. They were based on phylogenetic trees constructed using 18S ribosomal RNA genes. They have a steroid hormone known as ecdysteroids which regulates the metamorphosis process.

Ecdysozoa include the nematodes, arthropods, onychophorans , and tardigrades, whereas lophotrochozoan include flatworms, nemerteans, mollusks, annelids, lophophorate, and rotifer. Chordates, Echinoderms are the common deuterostomia.