Railway Science (Biology – Animal Kingdom) (Part-II)

Triploblastic animals - Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm; Examples - Frogs, Flatworms, Humans.
The Scyphozoa is a class of the phylum Cnidaria, sometimes referred to as the true jellyfish; Examples - Aurelia (moon jellies), Cannonball jellyfish, Cassiopea, Rhizostomeae.

Features of Arthropoda (joint leg) - body is triploblastic, segmented and bilaterally symmetrical. Body is divided into head, thorax and abdomen, has jointed appendages which help in locomotion, have an open circulatory system, exoskeleton is made of chitin, unisexual and fertilization is either external or internal, respire through the general body surface or trachea. Examples - Insects, Spiders, Scorpions, Centipedes and millipedes, Crabs, Shrimp, Lobsters and barnacles.