Lophotrochozoa vs Ecdysozoa
Difference between lophotrochozoa and ecdysozoa, the two major bilaterian, is discussed in this article. Based on the recent studies using nuclear and mitochondrial DNA sequences, scientists revised the taxonomy of Animal Kingdom. According to the new molecular phylogenies, scientists identify deutersomes as a separate natural group. Moreover, the major group of protostomes is now divided into two monophyletic bilaterian groups called Lophotrochozoa and Ecdysozoa. Hence, the Animal Kingdom now consists of three major monophyletic clades of bilateral animals; lophotrochozoa, ecdysozoa, and deuterstomia. The clade dueterostomia is further divided into two subgroups; (a) ambulacraria, which includes echinoderms, and (b) chordate, which comprises urochordates, cephalochordates and vertebrates. Lophotrochozoa and ecdysozoa are further divided into more and more subgroups based on their molecular phylogenies.
What is Lophotrochozoa?
The characteristic features of the group lophotrochozoa are the presence of a trochophore larvae and a feeding structure called lophophore. However, only few lophotrochozoans possess both of these characteristic features. Lophotrochozoans are sexually reproduced by releasing their gametes into the environment . Asexual reproduction is also common in this category. Every member of this group are triploblastic and shows bilateral symmetry. Both terrestrial and aquatic species are found in this group. Lophotrochozoa is subdivided into six subgroups; (a) Flatworms (Platyhelminthes, which includes turbellarians, trematodes, and cestodes), (b) Nemerteans (ribbon worms), Mollusks (chitons, gastropods such as snails, slugs, nudibranchs, bivalves like clams and oysters, cephalopods like squids and octopus), (c) Annelids (polychaetes like sandworms and tubeworms, oligochaetes including earthworms and freshwater worms, hirudinids, which includes leeches) , (d) Lophophorates (branchipods, phoronids, and bryozoans), and (e) Rotifera (wheel animals).
What is Ecdysozoa?
The name ecdysozoan is given to this group of animals due to the presence of special steroid hormone called ecdysteroids, which controls the process called ecdysis or metamorphosis. Ecdysozoans possess a cuticular skeleton and are able to shed the skeleton through the ecdysis. Most of the members in this group possess separate sexes. During the sexual reproduction, males deposit sperms inside the body of the female. Many ecdysozoans are solitary species, whereas some species live in colonies. Certain species show asexual reproduction through parthenogenesis.
The main subgroups of ecdysozoan include nematodas (roundworms), onychophorans (velvet worms), tardigrades (“water bears”), and arthropods. Phylum Arthropoda is the largest group with highest number of species and composed of mainly myriapods (centipedes, millipedes), chelicerates (horseshoe crabs, arachnids), crustaceans (lobsters, crabs, barnacles, copepods), and hexapods (insects).
What is the difference between Lophotrochozoa and Ecdysozoa?
• Ecdysozoans have the ability to shed their exoskeleton several times throughout their life span, whereas lophotrochozoan are the animals who possess a trochophore larvae and a feeding structure called lophophore.
• Unlike the lophotrochozoan, ecdysozoans possess a special steroid hormone called ecdysteroids.
• Ecdysozoa include the nematodes, arthropods, onychophorans , and tardigrades, whereas lophotrochozoan include flatworms, nemerteans, mollusks, annelids, lophophorate, and rotifer.