EVERYDAY SCIENCE

Detailed explanation-1: -They are triploblastic as they consist of three germ layers (ectoderm, mesoderm and endoderm ) during their embryonic development. They show bilateral symmetry that means body of these organisms can be cut into two equal halves in only one plane i.e. the median sagittal plane.

Detailed explanation-2: -Annelids are coelomate and triploblastic, which explains their name. They have an advanced level of organ system organization. Their bodies are seen in sections. They inhale and exhale via their whole body, not just their lungs.

Detailed explanation-3: -Organisms of Kingdom Animalia having three primary embryonic cell layers i.e., the ectoderm, mesoderm, and endoderm from which different tissues and organs of the animal’s body differentiate out are known as triploblastic. Examples are frog, flatworms, and humans.

Detailed explanation-4: -Triploblasty can be seen in multicellular animals, particularly, flatworms (Phylum Platyhelminthes), mollusks (Phylum Mollusca), arthropods (Phylum Arthropoda), and chordates (Phylum Chordata). Animals that are not triploblastic are some invertebrates like sponges (Phylum Porifera) and cnidarians (Phylum Cnidaria).

Detailed explanation-5: -Most authors accept the annelids as having three major classes: Polychaeta, Oligochaeta, and Hirudinea. Older systems would place the polychaetes and oligochaetes under the class Chaetopoda because both groups possess setae.